We issued technical specifications for the installation of current transformers. Current transformers general technical specifications. Permissible error range for transformers of various accuracy classes
GOST 7746-2001
INTERSTATE STANDARD
CURRENT TRANSFORMERS
General technical conditions
INTERSTATE COUNCIL
ON STANDARDIZATION, METROLOGY AND CERTIFICATION
Minsk
Preface
1 DEVELOPED by Open Joint Stock Company OJSC Sverdlovsk Current Transformer Plant
INTRODUCED by Gosstandart of Russia
2 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Protocol No. 20 of November 1, 2001)
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State name |
Name of the national standardization body |
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The Republic of Azerbaijan |
Azgosstandart |
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Republic of Armenia |
Armgosstandard |
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Republic of Belarus |
State Standard of Belarus |
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Republic of Georgia |
Gruzstandart |
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The Republic of Kazakhstan |
Gosstandart of the Republic of Kazakhstan |
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Republic of Kyrgyzstan |
Kyrgyzstandard |
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The Republic of Moldova |
Moldovastandard |
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Russian Federation |
Gosstandart of Russia |
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The Republic of Tajikistan |
Tajikstandard |
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Turkmenistan |
Main State Service "Turkmenstandartlary" |
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The Republic of Uzbekistan |
Uzgosstandart |
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Ukraine |
State Standard of Ukraine |
3 This standard meets the requirements of the international standard IEC 44-1:1996 “Measuring transformers. Part 1. Current transformers"
4 By Decree of the State Committee of the Russian Federation for Standardization and Metrology dated March 13, 2002 No. 92-st, the interstate standard GOST 7746-2001 was put into effect directly as the state standard of the Russian Federation from January 1, 2003.
5 INSTEAD GOST 7746-89
Content
INTERSTATE STANDARD
CURRENT TRANSFORMERS
General technical conditions
Current transformers.General specifications
date introduction 2003-01-01
1 area of use
This standard applies to electromagnetic current transformers (hereinafter referred to as transformers) with a rated voltage from 0.66 to 750 kV inclusive, intended for transmitting a signal of measurement information to measuring, protection, automation, signaling and control devices in alternating current electrical circuits with a frequency of 50 or 60 Hz .
Additional requirements for certain types of transformers in connection with the specifics of their design or purpose (for example, for cascade transformers, transformers designed to operate with standardized accuracy in transient modes, for installation in complete switchgears (switchgear), phase-shielded current conductors) should be established in the standards , technical specifications, agreements or contracts (hereinafter referred to as standards) for specific types of transformers.
The standard does not apply to laboratory, zero-sequence, summing, blocking, and saturable transformers.
2 Normative references
This standard uses references to the following standards:
GOST 2.601-95 Unified system of design documentation. Operational documents
GOST 8.217-87 State system for ensuring the uniformity of measurements. Current transformers. Verification method
GOST 12.2.007.0-75 System of occupational safety standards. Electrical products. General safety requirements
GOST 12.2.007.3-75 System of occupational safety standards. Electrical devices for voltages above 1000 V. Safety requirements
GOST 12.3.019-80 System of occupational safety standards. Electrical tests and measurements. General safety requirements
GOST 15.001-88 1) System for developing and putting products into production. Products for industrial and technical purposes
____________
1) GOST R 15.201-2000 is in force in the Russian Federation.
GOST 15.309-98 System for developing and launching products into production. Testing and acceptance of manufactured products. Basic provisions
GOST 27.003-90 Reliability in technology. Composition and general rules for specifying reliability requirements
GOST 403-73 Electrical devices for voltages up to 1000 V. Permissible heating temperatures for parts of devices
GOST 1516.1-76 AC electrical equipment for voltages from 3 to 500 kV. Requirements for electrical insulation strength
GOST 1516.2-97 Electrical equipment and electrical installations of alternating current for voltage 3 kV and higher. General test methods for electrical insulation strength
GOST 1516.3-96 AC electrical equipment for voltages from 1 to 750 kV. Requirements for electrical insulation strength
GOST 2933-93 1) Low-voltage electrical devices. Test methods
__________
1) In the Russian Federation, GOST 2933-83 is in force.
GOST 3484.1-88 Power transformers. Electromagnetic Test Methods
GOST 3484.5-88 Power transformers. Tank leak testing
GOST 6581-75 Liquid electrical insulating materials. Electrical Test Methods
GOST 8024-90 AC apparatus and electrical devices for voltages above 1000 V. Heating rate for continuous operation and test methods
GOST 9920-89 (IEC 694-80, IEC 815-86) AC electrical installations for voltages from 3 to 750 kV. External insulation creepage distance
GOST 10434-82 Electrical contact connections. Classification. General technical requirements
GOST 13109-97 Electrical energy. Electromagnetic compatibility of technical equipment. Standards for the quality of electrical energy in general-purpose power supply systems
GOST 14192-96 Marking of cargo
GOST 15150-69 Machines, instruments and other technical products. Versions for different climatic regions. Categories, operating, storage and transportation conditions regarding the impact of environmental climatic factors
GOST 15543.1-89 Electrical products. General requirements regarding resistance to climatic external influences
GOST 15963-79 Electrical products for areas with tropical climates. General technical requirements and test methods
GOST 16504-81 System of state testing of products. Testing and quality control of products. Basic terms and definitions
GOST 16962.1-89 (IEC 68-2-1-74) Electrical products. Test methods for resistance to climatic external influences
GOST 16962.2-90 Electrical products. Test methods for resistance to mechanical external influences
GOST 17516.1-90 Electrical products. General requirements regarding resistance to mechanical external influences
GOST 18425-73 Filled transport containers. Free fall impact test method
GOST 18685-73 Current and voltage transformers. Terms and Definitions
GOST 19880-74 Electrical engineering. Basic concepts. Terms and Definitions
GOST 20074-83 Electrical equipment and electrical installations. Method for measuring partial discharge characteristics
GOST 20690-75 AC electrical equipment for voltage 750 kV. Requirements for electrical insulation strength
GOST 21130-75 Electrical products. Grounding clamps and grounding signs. Design and dimensions
GOST 21242-75 Flat and pin contact terminals for electrical devices. Main Dimensions
GOST 23216-78 Electrical products. Storage, transportation, temporary anti-corrosion protection, packaging. General requirements and test methods
RMG 29-99 State system for ensuring the uniformity of measurements. Metrology. Basic terms and definitions
3 Definitions
The terms used in this standard and their corresponding definitions are according to RMG 29, GOST 16504, GOST 18685, GOST 19880, as well as the following:
3.1 nominal safety factor of devices : The ratio of the rated safety current of the appliances to the rated primary current of the transformer.
3.2 rated safety current of devices : The minimum value of the transformer primary current at which the total error is at least 10% at the rated secondary load.
3.3 type approval test: A type of state metrological control of a newly developed transformer, carried out in order to ensure the uniformity of measurements, approve the type of transformer and enter it into the State Register of Measuring Instruments.
3.4 type approval test: A type of state metrological control carried out periodically in order to determine the conformity of transformers released from production to the approved type.
3.5 permissible error range: The area beyond which transformer errors should not extend.
UDC 621.314.224:006.354 Group E64
INTERSTATE STANDARD
CURRENT TRANSFORMERS
General technical conditions
Current transformers. General specifications
ISS 17.220.20
Date of introduction 2003-01-01
Preface
1 DEVELOPED by Open Joint Stock Company OJSC Sverdlovsk Current Transformer Plant
INTRODUCED by Gosstandart of Russia
2 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Minutes No. 20 of November 1.)
|
State name |
Name of the national standardization body |
|
The Republic of Azerbaijan |
Azgosstandart |
|
Republic of Armenia |
Armgosstandard |
|
Republic of Belarus |
State Standard of Belarus |
|
Republic of Georgia |
Gruzstandart |
|
The Republic of Kazakhstan |
Gosstandart of the Republic of Kazakhstan |
|
Republic of Kyrgyzstan |
Kyrgyzstandard |
|
The Republic of Moldova |
Moldovastandard |
|
Russian Federation |
Gosstandart of Russia |
|
The Republic of Tajikistan |
Tajikstandard |
|
Turkmenistan |
Main State Service "Turkmenstandartlary" |
|
The Republic of Uzbekistan |
Uzgosstandart |
|
State Standard of Ukraine |
3 This standard meets the requirements of the international standard IEC 44-1:1996 “Measuring transformers. Part 1. Current transformers"
4 Resolution of the State Committee of the Russian Federation for Standardization and Metrology dated March 13. No. 92-st interstate standard GOST 7746-2001 came into force directly as a state standard of the Russian Federation on January 1.
5 INSTEAD GOST 7746-89
1 area of use
This standard applies to electromagnetic current transformers (hereinafter referred to as transformers) with a rated voltage from 0.66 to 750 kV inclusive, intended for transmitting a signal of measurement information to measuring, protection, automation, signaling and control devices in alternating current electrical circuits with a frequency of 50 or 60 Hz .
Additional requirements for certain types of transformers in connection with the specifics of their design or purpose (for example, for cascade transformers, transformers designed to operate with standardized accuracy in transient modes, for installation in complete switchgears (switchgear), phase-shielded current conductors) should be established in the standards , technical specifications, agreements or contracts (hereinafter referred to as standards) for specific types of transformers.
The standard does not apply to laboratory, zero-sequence, summing, blocking, and saturable transformers.
GOST 2.601-95 Unified system of design documentation. Operational documents
GOST 8.217-87 State system for ensuring the uniformity of measurements. Current transformers. Verification method
GOST 12.2.007.0-75 System of occupational safety standards. Electrical products. General safety requirements
GOST 12.2.007.3-75 System of occupational safety standards. Electrical devices for voltages above 1000 V. Safety requirements
GOST 12.3.019-80 System of occupational safety standards. Electrical tests and measurements. General safety requirements
GOST 15.001-881) System for developing and putting products into production. Products for industrial and technical purposes
1) GOST R 15.201-2000 is in force in the Russian Federation.
GOST 15.309-98 System for developing and launching products into production. Testing and acceptance of manufactured products. Basic provisions
GOST 27.003-90 Reliability in technology. Composition and general rules for specifying reliability requirements
GOST 403-73 Electrical devices for voltages up to 1000 V. Permissible heating temperatures for parts of devices
GOST 1516.1-76 AC electrical equipment for voltages from 3 to 500 kV. Requirements for electrical insulation strength
GOST 1516.2-97 Electrical equipment and electrical installations of alternating current for voltage 3 kV and higher. General test methods for electrical insulation strength
GOST 1516.3-96 AC electrical equipment for voltages from 1 to 750 kV. Requirements for electrical insulation strength
GOST 2933-931) Low-voltage electrical devices. Test methods
1) GOST 2933-83 is in force in the Russian Federation.
GOST 3484.1-88 Power transformers. Electromagnetic Test Methods
GOST 3484.5-88 Power transformers. Tank leak testing
GOST 6581-75 Liquid electrical insulating materials. Electrical Test Methods
GOST 8024-90 AC apparatus and electrical devices for voltages above 1000 V. Heating rate for continuous operation and test methods
GOST 9920-89 (IEC 694-80, IEC 815-86) AC electrical installations for voltages from 3 to 750 kV. External insulation creepage distance
GOST 10434-82 Electrical contact connections. Classification. General technical requirements
GOST 13109-97 Electrical energy. Electromagnetic compatibility of technical equipment. Standards for the quality of electrical energy in general-purpose power supply systems
GOST 14192-96 Marking of cargo
GOST 15150-69 Machines, instruments and other technical products. Versions for different climatic regions. Categories, operating, storage and transportation conditions regarding the impact of environmental climatic factors
GOST 15543.1-89 Electrical products. General requirements regarding resistance to climatic external influences
GOST 15963-79 Electrical products for areas with tropical climates. General technical requirements and test methods
GOST 16504-81 System of state testing of products. Testing and quality control of products. Basic terms and definitions
GOST 16962.1-89 (IEC 68-2-1-74) Electrical products. Test methods for resistance to climatic external influences
GOST 16962.2-90 Electrical products. Test methods for resistance to mechanical external influences
GOST 17516.1-90 Electrical products. General requirements regarding resistance to mechanical external influences
GOST 18425-73 Filled transport containers. Free fall impact test method
GOST 18685-73 Current and voltage transformers. Terms and Definitions
GOST 19880-74 Electrical engineering. Basic concepts. Terms and Definitions
GOST 20074-83 Electrical equipment and electrical installations. Method for measuring partial discharge characteristics
GOST 20690-75 AC electrical equipment for voltage 750 kV. Requirements for electrical insulation strength
GOST 21130-75 Electrical products. Grounding clamps and grounding signs. Design and dimensions
GOST 21242-75 Flat and pin contact terminals for electrical devices. Main Dimensions
GOST 23216-78 Electrical products. Storage, transportation, temporary anti-corrosion protection, packaging. General requirements and test methods
RMG 29-99 State system for ensuring the uniformity of measurements. Metrology. Basic terms and definitions
3 Definitions
The terms used in this standard and their corresponding definitions are according to RMG 29, GOST 16504, GOST 18685, GOST 19880, as well as the following:
3.1 rated safety factor of devices: The ratio of the rated safety current of devices to the rated primary current of the transformer.
3.2 rated safety current of devices: The minimum value of the primary current of a transformer at which the total error is at least 10% at the rated secondary load.
3.3 test for type approval: Type of state metrological control of a newly developed transformer, carried out in order to ensure uniformity of measurements, approve the type of transformer and enter it into the State Register of Measuring Instruments.
3.4 test for compliance with the approved type: A type of state metrological control carried out periodically in order to determine the conformity of transformers released from production to the approved type.
3.5 permissible error range: The area beyond which transformer errors should not extend.
4 Classification
4.1 Transformers are divided according to the following main characteristics:
4.1.1 By type of installation (location category and climatic version) according to GOST 15150.
When placing transformers inside the shells of complete products, the placement categories must correspond to those indicated in Table 1.
4.1.2 By design principle: support, walk-through, busbar, built-in, detachable.
A combination of several of the listed features in the transformer design, as well as a special design, is allowed.
4.1.3 By type of insulation: with cast insulation, with a porcelain cover, in a plastic case, with solid insulation (except porcelain and cast) or with a polymer cover, oil-filled, gas-filled.
4.1.4 According to the number of transformation stages: single-stage, cascade.
4.1.5 By the number of secondary windings: with one secondary winding, with several secondary windings.
4.1.6 According to the purpose of the secondary windings: for measurement and metering, for protection1), for measurement and protection, for operation with standardized accuracy in transient modes.
4.1.7 By the number of transformation ratios: with one transformation ratio, with several transformation ratios obtained by changing the number of turns of the primary and/or secondary windings, as well as by using several secondary windings with different numbers of turns, corresponding to different values of the rated secondary current.
4.1.8 Features according to 4.1.2, 4.1.3, 4.1.4, 4.1.6 and their designations are given in tables 2 - 4.
table 2
Table 3
Table 4
5 Basic parameters
5.1 Transformer ratings:
a) rated voltage of the transformer Unom (except for built-in transformers);
b) rated primary current of the transformer I1nom;
c) rated secondary current of the transformer I2nom;
d) nominal transformer ratio nnom, determined by the formula
e) rated secondary load S2nom with power factor cos ??2 = 1 or cos ??2 = = 0.8| - |S2nom (secondary load designation Z2nom is allowed);
f) accuracy class of the transformer (for a transformer with one secondary winding) or secondary windings (for a transformer with several secondary windings);
g) rated maximum factor of the secondary winding intended for protection, Knom
i) the nominal safety factor of devices of the secondary winding intended for measurement, -KBnom;
(ST SEV 2733-80,
MPEI 44-4 (1980),
IEC 185 (1987)
Official publication
USSR STATE COMMITTEE ON STANDARDS Moscow
UDC 621.314.224:006.354 Group E64
STATE STANDARD OF THE USSR UNION
CURRENT TRANSFORMERS General technical conditions
Current transformers. General specifications
(ST SEV 2733-80, IEC 44-4 (1980), IEC 185 (1987)
Valid from 01/01/90 to 01/01/95
Failure to comply with the standard is punishable by law
This standard applies to electromagnetic current transformers (hereinafter referred to as transformers) with a rated voltage from 0.66 to 750 kV inclusive, intended for transmitting a signal of measuring information to measuring instruments and (or) protection and control devices in alternating current installations with a frequency of 50 or 60 Hz , manufactured for the needs of the national economy and export.
The standard does not apply to laboratory, reference, zero-sequence, summing, blocking and saturable transformers.
The terms used in this standard are in accordance with GOST 18685, GOST 16504.
Official edition E
Reproduction is prohibited
© Standards Publishing House, 1989
rated current 5 A, intended for commercial electricity metering.
2. Accuracy classes Q.2S and 0.55 may be used by agreement between the manufacturer and the consumer for transformers, the technical specifications for which were approved after the introduction of this standard.
Errors should not go beyond the boundaries of broken lines consisting of segments drawn through the points of permissible errors.
For transformers with secondary load ratings greater than 60 VA, the lower secondary load limit shall be 15 VA, with secondary load ratings of 1; 2; 2.5; 3; 5 and 10 V-A lower limit of secondary loads - 0.8; 1.25; 1.5; 1.75; 3.75 and 3.75 VA respectively.
3.4.3. The permissible error limits of the secondary windings for protection under operating conditions of use according to clause 3.4.1 in steady state must correspond to those indicated in the table. 4.
Table 4
3.4.4. Metrological characteristics of transformers (secondary windings of transformers) for protection, designed to operate with standardized accuracy in transient modes, and methods for testing them should be established in the standards for specific types of transformers.
3.4.5. By agreement between the consumer and the manufacturer, the operational documentation for transformers must indicate the dependence of the errors on the influencing factors of the primary current, secondary load, frequency and temperature, as well as dynamic characteristics. Dependences of errors on each influencing factor are given at the nominal value of all other influencing factors and are provided with an indication of the accuracy of their determination.
3.5. Heating Requirements
3.5.1. With regard to heating during continuous operation of the flow of the highest operating primary currents (rated currents of long-term operation), transformers (with the exception of built-in ones operating in transformer oil) for rated voltages St. 0.66 kV must meet the requirements of GOST
1. CLASSIFICATION
S. 2 GOST 7746-“9
1.1. Transformers are divided according to the following main characteristics.
1.1.1. By type of installation:
for work in enclosed spaces (location categories 3 and 4 according to GOST 15150);
for work inside electrical equipment enclosures (placement categories - in accordance with Table 1).
Characteristics of the environment inside the shell
1.1.2. According to the design principle: support (O), pass-through (P), busbar (W), built-in (B), detachable (P).
A combination in the design of a transformer of several of the listed principles is allowed, as well as a special design that does not fall under the listed characteristics.
1.1.3. By type of insulation: with cast insulation (L), with porcelain cover (F), with solid insulation (except porcelain and cast) (T), oil-filled (M), gas-filled (G).
1.1.4. According to the number of transformation stages: single-stage, cascade.
1.1.5. According to the number of secondary windings: with one secondary winding, with several secondary windings.
1.1.6. According to the purpose of the secondary windings: for measurement, for protection, for measurement and protection, for operation with standardized accuracy in transient modes.
1.1.7. According to the number of transformation ratios: with one transformation ratio, with several transformation ratios obtained by changing the number of turns of the primary
GOST 7746-8" P. 3
nal and/or secondary windings, as well as by using several secondary windings with different numbers of turns corresponding to different values of the rated secondary current.
2. BASIC (NOMINAL) PARAMETERS
2.1. The nominal parameters of the transformer include:
1) rated voltage of the transformer U Nom (except for built-in ones);
2) rated primary current of the transformer /vol/
3) rated secondary current of the transformer / 2 „ ohm;
4) rated transformation ratio of the transformer
** nom- T~ 1 >
5) rated secondary load with power factor cos 6) nominal accuracy class of the transformer (for a transformer with one secondary winding) or secondary winding (for a transformer with several secondary windings); 7) nominal maximum multiplicity of the secondary winding intended for protection, /Snom/ 8) the nominal safety factor of the devices of the secondary winding intended for measurement, /(in nominal, if a nominal maximum multiplicity is not established for it (for transformers, the technical specifications for which were approved after the introduction of this standard); 9) nominal frequency /nom = 50 or 60 Hz. Note. The rated safety factor of devices is the ratio of the rated safety current of devices to the rated primary current of the transformer. The rated safety current of devices is the primary current at which the total error is at least 10% at the rated secondary load. 2.2. The values of the nominal parameters specified in clause 2.1 should be selected from those given in table. 2. table 2 S. A GOST 7746-“9 Continuation of the table. 2 Parameter name Parameter value 3 Rated primary current of the transformer Lnom, A 1; 5; 10; 15; 20; 30; 40; 50; 75; 80; 100; 150; 200; 300; 400; 500; 600; 750; 800; 1000; 1200; 1500; 2000; 3000; 4000; 5000; 6000; 8000; 10000; 12000; 14000; 16000; 18000; 20000; 25000; 28000; 30000; 32000; 35000; 40000 4. Rated secondary current* /gnome, A 5. Maximum operating primary current**, / !n p, A See table. 5 6. Rated secondary load 5 2N ohm with cos power factor<р 2 = 1, В А 7. Rated secondary load* S 2H0M, with power factor cos f 2 ^0.8 (inductive), VA** 3; 5; 10; 16; (20): (25); 30; (40); (50); 60; (75); (100) 8. Nominal accuracy class of transformer or secondary winding: for measurement for protection 0.1; 0.2; 0.2S; 0.5; 0.5S 1; 3; 5; 10*** 9. Nominal maximum factor of secondary windings for protection /Snom From 5 to 30. At the request of the consumer, it is allowed to set other values in the standards for specific types of transformers Yu Nominal safety factor of DEVICES K ynom Established in standards for specific types of transformers * The values indicated in brackets should not be used in transformers for which the technical specifications (TOR) were approved after the introduction of this standard. ** The corresponding values of the rated secondary load (Z 2H o M) in ohms are determined from the expression 2NOM That ‘ * ** *** ***Only for built-in transformers with rated primary current Up to 100 A. 2.3. Transformer symbol structure*. T X X x-x x-x-x/x - X/X XX Rated secondary current, A Rated primary current. A (if the transformer has several primary currents, indicate all values through a dash) Nominal accuracy class (if a transformer has several secondary windings, indicate the accuracy class of each of them in the form of a fraction) Design option, if there are several of them (Arabic or Roman numerals) Rated voltage, kV M (only for upgraded products) Designation according to clause 1.1.3 Designation according to clause 1.1.2 Product designation * For transformers for which the technical specifications were approved before the introduction of this standard, it is allowed to use the previously existing designation structure. An example of the designation of the first design version of a reference, oil-filled current transformer for a rated voltage of 330 kV, category B along the length of the leakage distance of external insulation, with five secondary windings of accuracy classes 0.2 and YUR, for a rated primary current of 3000A, rated secondary current of 1A, climatic version U, placement category 1: TOM ZZOB-1-0.2/YUR/lOP/lOPfYUR-3000/1U1 Notes: 1. The letter part of the symbol represents the series; a combination of letter designation, rated voltage value, external insulation category along the creepage distance and design option - type; The above designation in general is the type of transformer. 2. For built-in transformers, a simplified symbol may be used. 3. In the standards for transformers of specific types, it is allowed to introduce additional letters into the letter part, exclude or replace individual letters (except T) to indicate the features of a particular transformer, for example, for transformers designed to operate with standardized accuracy in transient modes. 3. TECHNICAL REQUIREMENTS 3.1. Transformers should be manufactured in accordance with the requirements of this standard, standards or technical specifications for transformers of specific series or types (standards for transformers of specific types) according to working drawings approved in the prescribed manner. Additional requirements for certain types of transformers, for example, for transformers for complete switchgears (KRU), for transformers for phase-shielded current conductors, etc., as well as special requirements for explosion-proof, seismic-resistant, resistant to chemically active environments, etc. transformers for vehicles, for special thermal installations, with gas insulation are indicated in the standards for specific types of transformers. The list of additional reference data for transformers, which, at the customer’s request, should be provided in information materials, is listed in Appendix 1. 3.2. General requirements 3.2.1. Transformers should be manufactured in climatic versions U, UHL, KHL, T or O in accordance with GOST 15150 and GOST 15543. Placement categories in accordance with GOST 15150: 1, 2, 3, 4 - for oil transformers; 1, 2, 3, 4, 5 - for dry transformers. The type of climatic modification and placement category according to GOST 15150 are indicated in the standards for specific types of transformers. Transformers must meet the requirements of GOST 15150 and GOST 15543. In addition, transformers of climatic versions UHL and KhL must meet the requirements of GOST 17412 and regulatory and technical documentation approved in the prescribed manner, and transformers of T and O versions must meet the requirements of GOST 15963. 3.2.2. Transformers must be designed to operate at an installation altitude above sea level of up to 1000 m, with the exception of transformers with a rated voltage of 750 kV, which which must be designed to operate at installation heights of up to 500 m. It is allowed, by agreement between the consumer and the manufacturer, to produce transformers for operation at a height of St. 1000 m, but not more than 3500 m. 3.2.3. Transformers for rated voltage up to 35 kV incl. must be designed for both grounded and grounded electrical systems. and with isolated neutral. Transformers with rated voltages of 110 kV and higher must be designed only for systems with a grounded neutral (with a ground fault factor of 1.4 according to GOST 1516.1). 3.3. Insulation requirements 3.3.1. Insulation of the primary winding (primary circuit) of transformers for rated voltages from 3 to 500 kV inclusive. must meet the requirements of GOST 1516.1, and for a rated voltage of 750 kV - the requirements of GOST 20690. The insulation of the primary winding (primary circuit) of transformers with a rated voltage of 0.66 kV must withstand a test voltage of 3 kV * frequency 50 Hz for 1 min. Additional insulation requirements for placement category 2 transformers that have their own primary winding, determined by moisture condensation (dew), should be specified in the standards for specific types of transformers. 3.3.2. For transformers of placement category 1, the leakage distance of external insulation is established according to GOST 9920. The transformer category, depending on the length of the creepage path (A, B or C), is indicated in the standards for specific types of transformers. 3.3.3. Intersectional insulation of sections of primary and secondary windings intended to change the transformation ratio of transformers must withstand a test voltage of 3 kV* at a frequency of 50 Hz for 1 minute. 3.3.4. The insulation of the secondary windings of transformers relative to grounded parts, and for transformers with several secondary windings, also relative to each other, must withstand a test voltage of 3 kV* at a frequency of 50 Hz for 1 minute. 3.3.5. The interturn insulation of the transformer windings must withstand, without breakdown or damage for 1 min, the voltage induced in them when a current flows through the primary winding, the value of which must be equal to the rated current. * For transformers, the technical specifications for which were approved before the introduction of this standard - 2 kV. mu current, if the voltage amplitude between the terminals of the open secondary winding does not exceed 4.5 kV* or less than the rated current, while the voltage amplitude between the terminals of the open secondary winding must be 4.5 kV*. During presentation and acceptance tests for transformers for rated voltages up to 10 kV inclusive. and rated primary current up to 6000 A inclusive. It is allowed to reduce the time of exposure to the test voltage to 5 s, if this is specified in the standards for specific types of transformers. 3.3.6. Requirements for the insulation of intermediate windings of cascade transformers are established in the standards for specific types of transformers. 3.3.7. Capacitor paper-oil insulation of the primary windings of transformers must meet the following requirements: intensity of partial discharges at a test voltage of 1.1 -D==: should not exceed 1-10“ p C or at a voltage of 1.3 D== should not exceed 5‘10 -11 C; dielectric loss tangent at temperature (25± ±10)°С and voltage 1.0 should not exceed 0.0035, and its increase at voltage from 0.5 to 1.0 should not exceed embroider 0.0003. For transformers with solid and cast insulation for voltages of 6 kV and higher, the standards for specific types of transformers establish standards for the intensity of partial discharges. 3.4. Metrological characteristics 3.4.1. Operating conditions for the use of transformers: 1) alternating current frequency (50±0.5) Hz or (60±0.5) Hz; 2) primary current - in accordance with clause 3.4.2; 3) the value of the secondary load - in accordance with clause 3.4.2; 4) ambient temperature - in accordance with the standards for specific types of transformers; 5) installation height of transformers above sea level according to clause 3.2.2. 3.4.2. Limits of permissible errors of secondary windings for measurement under operating conditions of use according to clause 3.4.1 with us- * For transformers, the technical specifications for which were approved before the introduction of this standard - 3.5 kV. The current mode must correspond to those indicated in the table. 3. Table 3 Permissible error limit Primary current. Secondary load limit, % of nominal % of nominal They don’t standardize They don’t standardize I They don’t standardize I Notes: 1. Accuracy classes 0.2S and 0.55 only for transformers with secondary Page 1 of 7 GOST 7746-2001 Name of the national standardization body Azerbaijan Republic Republic of Armenia Republic of Belarus Republic of Georgia Republic of Kazakhstan Kyrgyz Republic Republic of Moldova Russian Federation Republic of Tajikistan Turkmenistan Republic of Uzbekistan Ukraine Azgosstandart Armgosstandart Gosstandart of Belarus Gruzstandart 3 This standard meets the requirements of the international standard IEC 44-1:1996 “Measuring transformers. Part 1. Current transformers" 4.1.2 By design principle: support, walk-through, busbar, built-in, detachable. A combination of several of the listed features in the design of a transformer is allowed, and Symbol Passage Built-in Sectional Single stage Cascade Table 3 Symbol With porcelain cover With solid and air insulation, with polymer cover CURRENT TRANSFORMERS INTERSTATE COUNCIL Minsk 1 DEVELOPED by Open Joint Stock Company OJSC Sverdlovsk Current Transformer Plant INTRODUCED by Gosstandart of Russia 2 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Protocol No. 20 of November 1, 2001) State name Name of the national standardization body The Republic of Azerbaijan Azgosstandart Republic of Armenia Armgosstandard Republic of Belarus State Standard of Belarus Republic of Georgia Gruzstandart The Republic of Kazakhstan Gosstandart of the Republic of Kazakhstan Republic of Kyrgyzstan Kyrgyzstandard The Republic of Moldova Moldovastandard Russian Federation Gosstandart of Russia The Republic of Tajikistan Tajikstandard Turkmenistan Main State Service "Turkmenstandartlary" The Republic of Uzbekistan Uzgosstandart State Standard of Ukraine 3 This standard meets the requirements of the international standard IEC 44-1:1996 “Measuring transformers. Part 1. Current transformers" 4 By Decree of the State Committee of the Russian Federation for Standardization and Metrology dated March 13, 2002 No. 92-st, the interstate standard GOST 7746-2001 was put into effect directly as the state standard of the Russian Federation from January 1, 2003. 5 INSTEAD GOST 7746-89 INTERSTATE STANDARD CURRENT TRANSFORMERS General technical conditions Current transformers. General specifications dateintroduction 2003-01-01
This standard applies to electromagnetic current transformers (hereinafter referred to as transformers) with a rated voltage from 0.66 to 750 kV inclusive, intended for transmitting a signal of measurement information to measuring, protection, automation, signaling and control devices in alternating current electrical circuits with a frequency of 50 or 60 Hz . Additional requirements for certain types of transformers in connection with the specifics of their design or purpose (for example, for cascade transformers, transformers designed to operate with standardized accuracy in transient modes, for installation in complete switchgears (switchgear), phase-shielded current conductors) should be established in the standards , technical specifications, agreements or contracts (hereinafter referred to as standards) for specific types of transformers. The standard does not apply to laboratory, zero-sequence, summing, blocking, and saturable transformers. GOST 2.601-95 Unified system of design documentation. Operational documents GOST 8.217-87 State system for ensuring the uniformity of measurements. Current transformers. Verification method GOST 12.2.007.0-75 System of occupational safety standards. Electrical products. General safety requirements GOST 12.2.007.3-75 System of occupational safety standards. Electrical devices for voltages above 1000 V. Safety requirements GOST 12.3.019-80 System of occupational safety standards. Electrical tests and measurements. General safety requirements GOST 15.001-88 1) System for developing and putting products into production. Products for industrial and technical purposes 1) GOST R 15.201-2000 is in force in the Russian Federation. GOST 15.309-98 System for developing and launching products into production. Testing and acceptance of manufactured products. Basic provisions GOST 27.003-90 Reliability in technology. Composition and general rules for specifying reliability requirements GOST 403-73 Electrical devices for voltages up to 1000 V. Permissible heating temperatures for parts of devices GOST 1516.1-76 AC electrical equipment for voltages from 3 to 500 kV. Requirements for electrical insulation strength GOST 1516.2-97 Electrical equipment and electrical installations of alternating current for voltage 3 kV and higher. General test methods for electrical insulation strength GOST 1516.3-96 AC electrical equipment for voltages from 1 to 750 kV. Requirements for electrical insulation strength GOST 2933-93 1) Low-voltage electrical devices. Test methods 1) GOST 2933-83 is in force in the Russian Federation. GOST 3484.1-88 Power transformers. Electromagnetic Test Methods GOST 3484.5-88 Power transformers. Tank leak testing GOST 6581-75 Liquid electrical insulating materials. Electrical Test Methods GOST 8024-90 AC apparatus and electrical devices for voltages above 1000 V. Heating rate for continuous operation and test methods GOST 9920-89 (IEC 694-80, IEC 815-86) AC electrical installations for voltages from 3 to 750 kV. External insulation creepage distance GOST 10434-82 Electrical contact connections. Classification. General technical requirements GOST 13109-97 Electrical energy. Electromagnetic compatibility of technical equipment. Standards for the quality of electrical energy in general-purpose power supply systems GOST 14192-96 Marking of cargo GOST 15150-69 Machines, instruments and other technical products. Versions for different climatic regions. Categories, operating, storage and transportation conditions regarding the impact of environmental climatic factors GOST 15543.1-89 Electrical products. General requirements regarding resistance to climatic external influences GOST 15963-79 Electrical products for areas with tropical climates. General technical requirements and test methods GOST 16504-81 System of state testing of products. Testing and quality control of products. Basic terms and definitions GOST 16962.1-89 (IEC 68-2-1-74) Electrical products. Test methods for resistance to climatic external influences GOST 16962.2-90 Electrical products. Test methods for resistance to mechanical external influences GOST 17516.1-90 Electrical products. General requirements regarding resistance to mechanical external influences GOST 18425-73 Filled transport containers. Free fall impact test method GOST 18685-73 Current and voltage transformers. Terms and Definitions GOST 19880-74 Electrical engineering. Basic concepts. Terms and Definitions GOST 20074-83 Electrical equipment and electrical installations. Method for measuring partial discharge characteristics GOST 20690-75 AC electrical equipment for voltage 750 kV. Requirements for electrical insulation strength GOST 21130-75 Electrical products. Grounding clamps and grounding signs. Design and dimensions GOST 21242-75 Flat and pin contact terminals for electrical devices. Main Dimensions GOST 23216-78 Electrical products. Storage, transportation, temporary anti-corrosion protection, packaging. General requirements and test methods RMG 29-99 State system for ensuring the uniformity of measurements. Metrology. Basic terms and definitions The terms used in this standard and their corresponding definitions are according to RMG 29, GOST 16504, GOST 18685, GOST 19880, as well as the following: 3.1 nominal safety factor of devices: The ratio of the rated safety current of the appliances to the rated primary current of the transformer. 3.2 rated safety current of devices: The minimum value of the transformer primary current at which the total error is at least 10% at the rated secondary load. 3.3 type approval test: A type of state metrological control of a newly developed transformer, carried out in order to ensure the uniformity of measurements, approve the type of transformer and enter it into the State Register of Measuring Instruments. 3.4 type approval test: A type of state metrological control carried out periodically in order to determine the conformity of transformers released from production to the approved type. 3.5 permissible error range: The area beyond which transformer errors should not extend. 4.1 Transformers are divided according to the following main characteristics: 4.1.1 By type of installation (location category and climatic version) according to GOST 15150. When placing transformers inside the shells of complete products, the placement categories must correspond to those indicated in Table 1. 4.1.2 By design principle: support, walk-through, busbar, built-in, detachable. A combination of several of the listed features in the transformer design, as well as a special design, is allowed. 4.1.3 By type of insulation: with cast insulation, with a porcelain cover, in a plastic case, with solid insulation (except porcelain and cast) or with a polymer cover, oil-filled, gas-filled. 4.1.4 According to the number of transformation stages: single-stage, cascade. 4.1.5 By the number of secondary windings: with one secondary winding, with several secondary windings. 4.1.6 According to the purpose of the secondary windings: for measurement and metering, for protection 1), for measurement and protection, for operation with standardized accuracy in transient modes. 4.1.7 By the number of transformation ratios: with one transformation ratio, with several transformation ratios obtained by changing the number of turns of the primary and/or secondary windings, as well as by using several secondary windings with different numbers of turns, corresponding to different values of the rated secondary current. 4.1.8 Features according to 4.1.2, 4.1.3, 4.1.4, 4.1.6 and their designations are given in tables 2 - 4. table 2 Transformer design Symbol Passage Built-in Sectional Single stage Cascade Table 3 Table 4 5.1 Transformer ratings: a) rated voltage of the transformer U nom (except for built-in transformers); b) rated primary current of the transformer I 1nom; c) rated secondary current of the transformer I 2nom; d) nominal transformer ratio of the transformer n nom determined by the formula f) accuracy class of the transformer (for a transformer with one secondary winding) or secondary windings (for a transformer with several secondary windings); g) the nominal maximum multiplicity of the secondary winding intended for protection, K nom; i) the nominal safety factor of the devices of the secondary winding intended for measurement, K Bnom; j) rated frequency of mains voltage f nom equal to 50 or 60 Hz. The quality of the network voltage is in accordance with GOST 13109. 5.2 The values of the main parameters should be selected from those given in Table 5. Table 5 Meaning 1 Transformer rated voltage U nom, kV 0,66; 3; 6; 10; 15; 20; 24; 27; 35; 110; 150; 220; 330; 500; 750 2 Highest operating voltage, kV For rated voltage 0.66 kV - 0.72; for 3 kV and above - according to GOST 1516.3 3 Rated primary current of the transformer I 1nom, A 1; 5; 10; 15; 20; 30; 40; 50; 75; 80; 100; 150; 200; 300; 400; 500; 600; 750; 800; 1000; 1200; 1500; 2000; 3000; 4000; 5000; 6000; 8000; 10000; 12000; 14000; 16000; 18000; 20000; 25000; 28000; 30000; 32000; 35000; 40000 4 Rated secondary current I 2nom, A 5 Highest operating primary current I 1np, A See table 10 3; 5; 10; 15; 20; 25; 30; 50; 60; 75; 100 8 Accuracy class of transformer or secondary winding: for measurements and accounting 0.1; 0.2; 0.2S 2) ; 0.5; 0.5S 2) ; 1; 3; 5; 10 3) for guard 9 Nominal maximum factor of secondary windings for protection K nom From 5 to 30 4) 10 Nominal safety factor of devices K Bnom, secondary windings for measurements They are established in standards for specific types of transformers. Not installed for secondary windings for measurements and protection 1) The corresponding values of the rated secondary load Z 2nom, Ohm, are determined by the formula 2) Accuracy classes 0.2S and 0.5S are allowed by agreement between the manufacturer and consumer of transformers intended for commercial electricity metering. 3) Only for built-in transformers with rated primary current up to 100 A. 4) At the request of the consumer, it is allowed to set other values in the standards for specific types of transformers. 5.3 Transformer symbol Notes 1 The letter part of the symbol represents the series; a combination of letter designation, rated voltage value, external insulation category along the creepage distance and design option - type; The above designation in general is the type of transformer. 2 For built-in transformers, a simplified symbol may be used. 3 In standards for transformers of specific types, it is allowed to introduce additional letters into the letter part, exclude or replace individual letters (except T) to indicate the features of a particular transformer. An example of a symbol for a reference current transformer with cast insulation for a rated voltage of 35 kV, category II in terms of the leakage distance of external insulation, with secondary windings of accuracy classes 0.5 (one) and 10P (three), for a rated primary current of 2000 A, rated secondary current 1 A, climatic version U, placement category 1: TOL - 35 - II - 0.5/10R/10R/10R - 2000/1U1 6.1 Transformers should be manufactured in accordance with the requirements of this standard and standards for specific types of transformers according to working drawings approved in the prescribed manner. The list of additional reference data for transformers, which, at the customer’s request, should be provided in information materials, is specified in Appendix A. 6.2 General requirements 6.2.1 Transformers should be manufactured in climatic versions in accordance with GOST 15150 and GOST 15543.1. Accommodation categories - according to GOST 15150. Requirements regarding resistance to climatic external influencing factors are in accordance with GOST 15543.1. 6.2.2 Transformers must be designed for operation at an altitude of up to 1000 m above sea level, with the exception of transformers with a rated voltage of 750 kV, which must be designed for operation at an altitude of up to 500 m. It is allowed, by agreement between the consumer and the manufacturer, to produce transformers for operation at an altitude of over 1000 m. 6.2.3 Resistance of transformers to mechanical environmental factors - according to GOST 17516.1. The mechanical performance group according to GOST 17516.1 is established in the standards for specific types of transformers. 500 N (50 kgf) - for transformers with rated voltage up to 35 kV inclusive; 1000 N (100 kgf) - for transformers with a rated voltage of 110 - 220 kV; 1500 N (150 kgf) - for transformers with a rated voltage of 330 kV and above. In this case, the values of test static loads should be 1) : 1250 N (125 kgf) - for transformers with rated voltage up to 35 kV inclusive; 2000 N (200 kgf) - for transformers with a rated voltage of 110 - 220 kV; 2500 N (250 kgf) - for transformers with a rated voltage of 330 kV and above. The values of the static test loads take into account the extreme dynamic loads that occur at the contact terminals of the transformer, for example, with short circuit currents not exceeding more than 1.4 times the static test loads. 1) The values of static test loads are indicated for transformers, the technical specifications for which were approved after 01/01/2001. 6.2.4 The operating position of transformers in space must be specified in the standards for specific types of transformers. 6.3 Insulation requirements 6.3.1 The insulation of the primary winding (primary circuit) of transformers for rated voltages from 3 to 500 kV inclusive must comply with the requirements of GOST 1516.1 and GOST 1516.3, and for a rated voltage of 750 kV - with the requirements of GOST 1516.3 and GOST 20690. For the insulation of the primary winding (primary circuit) of oil-filled transformers with a rated voltage of 330 kV and higher, by agreement between the consumer and the manufacturer, requirements for the effects of sheared lightning and multiple sheared pulses are allowed. The insulation of the primary winding (primary circuit) of transformers with a rated voltage of 0.66 kV must withstand a test voltage of 3 kV with a frequency of 50 Hz for 1 min. Additional insulation requirements for placement categories 2 and 5 transformers having their own primary winding, determined by moisture condensation (dew), and the creepage distance of external insulation must be specified in the standards for specific types of transformers. 6.3.2 For transformers of placement category 1 according to GOST 15150, the leakage distance of external insulation according to GOST 9920 must be established in the standards for specific types of transformers. 6.3.3 Intersectional insulation of sections of primary and secondary windings intended to change the transformation ratio of transformers must withstand the influence of a test voltage of 3 kV with a frequency of 50 Hz for 1 minute. 6.3.4 The insulation of the secondary windings of transformers relative to grounded parts, and for transformers with several secondary windings also relative to each other, must withstand a test voltage of 3 kV with a frequency of 50 Hz for 1 minute. 6.3.5 Gas insulation of the primary winding of transformers operating at excess gas pressure must withstand a voltage equal to , for 15 minutes, at an excess gas pressure equal to zero, where U np - highest operating voltage. 6.3.6 The level of partial discharges of the insulation of the primary winding of transformers with a rated voltage of 3 kV and above insulation level “a” according to GOST 1516.3 must correspond to those given in Table 6. Table 6 Type of insulation Measurement voltage Permissible level, pC Paper-oil Gas 1) 1) Does not apply to air-insulated transformers freely communicating with the outside air. The dielectric loss tangent of the capacitor paper-oil insulation of the primary winding of transformers at temperature (25 ± 10) °C and voltage should not exceed 0.0035, and its increase in the voltage range from to should not exceed 0.0003. 6.3.7 The interturn insulation of the transformer windings must withstand, without breakdown or damage for 1 min, the voltage induced in them when a current flows through the primary winding, the value of which must be rated if the voltage amplitude between the terminals of the open secondary winding does not exceed 4.5 kV or less nominal; in this case, the voltage amplitude between the terminals of the open secondary winding should be 4.5 kV. 6.3.8 Under normal climatic conditions according to GOST 15150, the insulation resistance value of transformer windings must be no less than: 40 MOhm - for the primary windings of transformers with a rated voltage of 0.66 kV; 1000 MOhm - for primary windings of transformers for rated voltages 3 - 35 kV; 3000 MOhm - for the primary windings of transformers for rated voltages of 110 - 220 kV; 5000 MOhm - for the primary windings of transformers with rated voltages of 330 kV and above; 20 MOhm - for secondary windings of transformers with a rated voltage of 0.66 kV; 50 MOhm - for secondary windings of transformers with rated voltages of 3 kV and above. 6.3.9 Dielectric quality indicators of oil of oil-filled transformers must correspond to those indicated in Table 7. Table 7 Oil quality indicator Transformer rated voltage, kV Limit permissible value of oil quality indicator for pouring into transformer after filling into the transformer Breakdown voltage according to GOST 6581, kV, not less Up to 15 incl. Up to 35 incl. Dielectric loss tangent at 90 °C according to GOST 6581, %, no more Up to 220 incl. 6.4 Metrological characteristics 6.4.1 Metrological characteristics should be established for the following operating conditions for using transformers: a) alternating current frequency (50 ± 0.5) Hz or (60 ± 0.5) Hz; b) primary current - in accordance with 6.4.2 and 6.4.3; c) secondary load value - in accordance with 6.4.2 and 6.4.3; d) ambient temperature - in accordance with the climatic design and placement category, unless otherwise specified in the standards for specific types of transformers; e) installation height of transformers above sea level - according to 6.2.2. 6.4.2 The limits of permissible errors of the secondary windings for measurements and metering under operating conditions of use according to 6.4.1 in steady state must correspond to the values indicated in Table 8. Errors should not go beyond the permissible areas. The permissible error ranges for various accuracy classes are given in Appendix B. For transformers with rated secondary loads 1; 2; 2.5; 3; 5 and 10 VA lower limit of secondary loads - 0.8; 1.25; 1.5; 1.75; 3.75 and 3.75 VA respectively. Table 8 Accuracy class Primary current, % of rated value Permissible error limit Secondary load limit, % of nominal value current,% ± 0.45 srad ± 0.24 srad ± 0.15 srad ± 0.45 srad ± 0.45 srad ± 1.35 srad ± 1.35 srad They don’t standardize 6.4.3 The limits of permissible errors of secondary windings for protection under operating conditions of use according to 6.4.1 at steady state and rated secondary load must correspond to those indicated in Table 9. Table 9 6.4.4 By agreement between the consumer and the manufacturer, the operational documentation for transformers must indicate the dependence of the errors on the influencing factors: primary current, secondary load, frequency and temperature, as well as dynamic characteristics. The dependences of errors on each influencing factor are determined at the nominal value of all other influencing factors and indicating the accuracy of the determination. 6.5 Magnetizing current value 6.5.1 The magnetizing current of the secondary windings for measurement, obtained during tests according to 9.8 and expressed as a percentage of a value equal to the product of the rated secondary current and the rated safety factor of the devices, must be at least 10%. 6.5.2 The magnetizing current of the secondary windings for protection, obtained during tests according to 9.8 and expressed as a percentage of a value equal to the product of the rated secondary current and the rated limit factor, must not exceed the total error values specified in Table 9. 6.5.3 The permissible value of the magnetizing current and the corresponding calculated voltage value must be established by the manufacturer taking into account the requirements of 6.5.1, 6.5.2 and are indicated in the operational documentation for specific transformers. 6.5.4 The measured values of the magnetizing current of the secondary windings must be recorded in the passport for a specific transformer. 6.6 Heating requirements 6.6.1 In the case of continuous flow of the highest operating primary currents (rated long-term currents), transformers (with the exception of built-in ones operating in transformer oil) for rated voltages above 0.66 kV must comply with the requirements of GOST 8024, and transformers for a rated voltage of 0.66 kV - requirements of GOST 403. For transformers operated at ambient temperatures different from those specified by GOST 15150 and GOST 15543.1, the upper operating value and (or) effective value of the ambient temperature must be established in the standards for specific types of transformers. For built-in transformers installed in oil circuit breakers, power oil transformers, autotransformers or reactors, and immersed in oil, the maximum permissible temperature rise above the oil temperature (90 °C for oil circuit breakers and 95 °C for power oil transformers, autotransformers or reactors) at over a long period of time should not exceed: 10 °C - for windings; 15 °C - for magnetic cores. For built-in transformers with rated primary currents over 10,000 A at an oil temperature surrounding the transformer below 90 °C for oil circuit breakers and below 95 °C for power oil transformers, autotransformers or reactors, the permissible temperature rises can be increased accordingly, but not more than 10 °C. 6.6.2 The highest operating primary currents of transformers with rated currents up to 10,000 A must correspond to those indicated in Table 10. For transformers whose effective ambient temperature according to GOST 15543.1 exceeds 40 °C, the values of the highest operating primary currents may be less than those indicated in Table 10 and they should be established in the standards for specific types of transformers. For transformers with rated primary currents over 10,000 A, intended for generators or synchronous compensators, the highest operating primary current may be greater or less than the rated current, but not less than the highest continuous current of the generator or synchronous compensator. By agreement between the consumer and the manufacturer, a short-term, no more than 2 hours per week, increase in the primary current by 20% relative to the highest operating primary current is allowed. Table 10 Parameter name Value, A Rated primary current I 1nom Highest operating primary current I 1nr Continuation of table 10 End of table 10 6.7 Requirements for resistance to short-circuit currents 6.7.1 Transformers for voltages above 0.66 kV must be resistant to electrodynamic 1) and thermal effects of short circuit currents, the parameters of which do not exceed the established values: a) current electrodynamic resistance i d or its multiples K d in relation to the amplitude of the rated primary current; b) thermal current I t or its multiples K t in relation to the rated primary current; c) time of current flow t k, equal to: 1 or 3 s - for transformers with rated voltages up to 220 kV inclusive; 1 or 2 s - for transformers with rated voltages of 330 kV and above. 1) There are no requirements for electrodynamic resistance for busbar, built-in and detachable transformers. 6.7.2 Between values i d and I t the ratio must be observed 6.7.3 The standards for specific types of transformers must establish: the value of the thermal resistance current or its multiple, the time of current flow, as well as the value of the electrodynamic resistance current or its multiple. 6.8 The DC resistance value of the secondary windings must be established by the manufacturer and indicated in the operational documentation. 6.9 Designation of winding terminals The terminals of the primary and secondary windings and the secondary windings of transformers should be designated in accordance with Table 11. The linear terminals of the primary winding, as well as the corresponding sides of busbar, built-in and detachable transformers that do not have their own primary winding, indicate L 1 and L 2 . The designations are applied in such a way that at the same moment in time the conclusions L 1 , N 1 ..., N n And AND 1 , ..., And n had the same polarity, i.e. so that when the current in the primary winding is directed from L 1 , N 1 , ..., N n To TO 1 , TO 2 ..., L 2 secondary current passed through the external circuit (devices) from AND 1 to AND 2 , ..., And n. Designations are made in capital letters of the Russian alphabet in combination with numbers. The numbers are placed on the same line with the letters (for example L 1) or in the index (for example L 1). Table 11 Transformer winding Designations of terminals and windings Primary With one section With several sections Secondary Transformer with one secondary winding: without branches with branches Secondary Transformer with multiple secondary windings: without branches with branches 6.10 Design requirements 6.10.1 Metal parts of the transformer that are susceptible to corrosion under the influence of environmental climatic factors must have a protective coating. 6.10.2 Contact terminals of the primary winding of transformers must comply with the requirements of GOST 10434, and for transformers of placement category 1 also with the requirements of GOST 21242. 6.10.3 Contact terminals of the secondary windings of transformers must comply with the requirements of GOST 10434. The contact terminals of the secondary windings of built-in transformers can be located in the structure of the product in which the transformer is built. 6.10.4 Transformers must have a contact pad for connecting a grounding conductor and a grounding clamp in accordance with the requirements of GOST 21130 and GOST 12.2.007.3. Near the grounding clamp there must be a grounding sign in accordance with GOST 21130. Grounding terminals of transformers of versions T and O must also comply with the requirements of GOST 15963. The requirements of this paragraph do not apply to built-in transformers, transformers with a body made of cast resin or plastic that do not have metal parts that must be grounded, as well as transformers that are not subject to grounding in accordance with GOST 12.2.007.0. 6.10.5 The design of oil-filled transformers must ensure their tightness. Standards for oil-filled transformers must contain requirements for checking the tightness of the structure, and for transformers with capacitor paper-oil insulation, also requirements for the gas and moisture content of the oil poured into transformers. 6.10.6 The design of transformers for rated voltages of 110 kV and above must ensure protection of the oil from moisture, preventing its direct contact with the atmosphere. 6.10.7 An oil-filled transformer must have an expander, the capacity of which must ensure the constant presence of oil in it under all operating modes of the transformer within the operating temperature range. The expander function can be performed by the top of a porcelain cover, a bellows, or other devices. Oil-filled transformers must be equipped with an oil level indicator or similar device that allows the oil level in the transformer to be monitored from a distance that is safe for operating personnel. If the oil weight is up to 20 kg, the oil level indicator may not be installed. Oil-filled transformers with an oil mass of more than 10 kg must be equipped with fittings for filling, sampling and draining oil, including for chromatographic analysis of gases dissolved in the oil. In this case, smooth regulation of the flowing oil stream must be provided. 6.10.8 Transformers weighing more than 20 kg must have a device in accordance with GOST 12.2.007.0 for lifting, lowering and holding them suspended. If it is impossible to construct such devices, the operating manual must indicate the places where the transformer will be grabbed during rigging work. 6.10.9 The design of transformers with secondary windings for measurement must provide one or more places for installing seals or imprinting a stamp on the verification of the transformer in accordance with GOST 8.217. 6.10.10 In transformers for voltages of 330 kV and above with capacitor paper-oil insulation, an outlet must be provided for connecting a device for monitoring insulation characteristics under operating voltage. 6.10.11 The design of gas-filled transformers must ensure gas mass leakage of no more than 1% per year. 6.10.12 The design of gas-filled transformers must be protected from an excessive increase in gas pressure in the event of an accident associated with breakdown of internal insulation and arcing. 6.10.13 The materials used in the construction of transformers must ensure compliance with explosion and fire safety requirements. 6.11 Reliability requirements 6.11.1 In the standards for specific types of transformers, the average time to failure should be established in accordance with GOST 27.003. 6.11.2 The average service life of transformers is 25 years. 6.11.3 Standards for specific types of transformers must establish maintainability requirements. 6.12 Completeness 6.12.1 The completeness of the transformer must be established in the standards for specific types of transformers. 6.12.2 Transformers are accompanied by operational documentation in accordance with GOST 2.601: passport, operation manual, spare parts list (if available). For transformers with a rated voltage of up to 10 kV, by agreement between the manufacturer and the consumer, if this is established in the standards for specific types of transformers, the passport can be replaced with a label. For transformers with a voltage of 0.66 kV, the range of operational documentation can be reduced and should be established in the standards for specific types of transformers. The number of copies of operational documents attached to transformers must be established in the standards for specific types of transformers. 6.13 Marking 6.13.1 Each transformer must have a plate(s) indicating: a) trademark or name of the manufacturer; b) name “current transformer”; c) type of transformer and climatic version; d) serial number according to the manufacturer’s numbering system; e) rated voltage, kV (except for built-in transformers); f) nominal frequency, Hz (at a frequency of 50 Hz it is allowed not to be specified); g) number of the secondary winding (only for transformers with two or more secondary windings); i) rated transformation ratio (in the form of the ratio of rated currents: primary and secondary), A; j) accuracy class for secondary windings in accordance with 6.4 1); l) nominal safety factor of devices K Bnom (for secondary windings intended for measurement) 2) ; m) value of the nominal maximum multiplicity K nom (for secondary windings intended for protection) 2); o) mass of the transformer, kg 3) ; o) designation of the standard for specific types of transformers or designation of this standard; p) year of manufacture (not indicated on transformers intended for export). 1) For secondary windings intended for measurement and protection, both nominal accuracy classes should be specified. 2) For transformers with a rated voltage of 0.66 kV, it is allowed K nom and K Do not indicate the numbers if they are given in the instruction manual. 3) Only for transformers weighing 10 kg or more, transported unassembled. Notes 1 It is allowed to apply the listed data on one or more plates, as well as partially or completely on the structural elements of the transformer. 2 If there is not enough space on the plate, data from the transfers is allowed d), e), And) - O) applied without indicating the name of the parameter (for example, 6 kV, 50 Hz), while the data according to the transfers To) - n) are applied in combination and sequence according to the following examples: 30 VA 5P 10 (nominal secondary load 30 VA, nominal accuracy class 5P, nominal maximum multiplicity 10); 20 VA 0.5 10 (rated secondary load 20 VA, rated accuracy class 0.5, rated safety factor of devices 10). 3 It is allowed, in addition to the data specified in this paragraph, to put additional information on the plate in accordance with the standard for specific types of transformers. For transformers with several secondary windings or with taps on the secondary windings, the following information is listed: And) - n) are indicated for each secondary winding and each branch. For integral transformers intended for use within another product, the rating plate(s) should be placed on the enclosure of that product and the transformers themselves should indicate: type of built-in transformer; nominal transformation ratio (in the presence of branches, indicate the highest transformation ratio); serial number according to the manufacturer's numbering system. 6.13.2 Parts of transformers transported disassembled must be marked to facilitate the assembly of transformers at the installation site. The types and methods of marking must be indicated in the operational documentation. 6.13.3 The method of marking on plates, as well as the method of marking winding terminals (6.9), must ensure legibility of the inscriptions throughout the entire operation of the transformer. 6.13.4 Labeling of transport containers - in accordance with GOST 14192. 6.14 Packaging 6.14.1 All unpainted metal parts of the transformer (including spare parts, if any), exposed to the external environment during transportation and storage, must be preserved using lubricants or other reliable means for a shelf life of 3 g. 6.14.2 Packaging must ensure the safety of transformers during transportation. The type of packaging must be specified in the standards for specific types of transformers. 7.1 Safety requirements for the design of transformers - in accordance with GOST 12.2.007.0 and GOST 12.2.007.3. 7.2 Safety requirements when testing transformers - according to GOST 8.217 and GOST 12.3.019. 8.1 To check the compliance of transformers with the requirements of this standard and the standard for specific types of transformers, tests should be carried out: for type approval; for compliance with the approved type; qualifying; acceptance; periodic; 8.2 The scope of tests and inspections, depending on the design features and purpose of the transformer, should be selected according to Table 12 and established in the standards for specific types of transformers. Table 12 Name of test and inspection Need for testing Clause of this standard for type approval for compliance with the approved type Qualification Acceptance Periodic Technical requirements Control methods 1 Check for compliance with the requirements of the assembly drawing 6.1; 6.9; 6.12.2 2 Testing the electrical strength of the primary winding with one-minute power frequency voltage 3 Test of primary winding insulation with lightning impulse voltage 1) 4 Insulation testing of oil-filled transformers with a rated voltage of 330 kV and above with clipped lightning impulse and multiple clipped impulses 5 Testing the electrical strength of insulation of transformers with a rated voltage of 330 kV and higher by switching impulse voltage 6 Testing the internal insulation of the primary winding for resistance to thermal breakdown 7 Checking creepage distance 8 Test of intersectional insulation of sectional windings 9 Testing the insulation of the primary winding of gas-filled transformers with a residual gas pressure equal to zero 10 Testing the electrical strength of insulation of secondary windings with one-minute power frequency voltage 11 Measurement of the level of partial discharges of transformers with insulation level “a” according to GOST 1516.3 12 Turn-to-turn insulation test 13 Measuring winding insulation resistance 14 Oil sample test for oil transformers: breakdown voltage determination determination of the dielectric loss tangent of oil transformers of voltage class 110 kV and higher determination of moisture and gas content, chromatographic analysis 15 Checking polarity 16 Determination of current and angular errors 17 Checking the maximum multiplicity (determining the total error) of the secondary windings for protection 18 Checking the safety factor of secondary winding devices for measurements 19 Determination of quantitative gas leakage of gas-filled transformers 20 Determination of the magnetizing current of the secondary windings 21 Heating test during continuous operation 22 Test for resistance to short-circuit currents (tests for electrodynamic and thermal resistance) 23 Measuring the resistance of secondary windings to direct current 24 Leak testing of oil-filled transformers 25 Tests for resistance to environmental climatic factors 26 Tests for resistance to mechanical factors 27 Strength test during transportation 28 Packaging drop test 29 Confirmation of mean time to failure 30 Testing gas-filled transformers for explosion safety 1) Not carried out for bus transformers. Note- The “+” sign means that the test is being carried out; sign “-” - do not carry out; the letter "O" means that the test is carried out if specified in the standard for a particular type of transformer. Tests of transformers designed to operate at frequencies of 50 and 60 Hz for compliance with all the requirements of this standard are carried out at a frequency of 50 Hz, as indicated in the passport. In this case, the test results of transformers designed to operate at a frequency of 60 Hz are not adjusted, except for the results of tests for heating during continuous operation and resistance to short-circuit currents, which should be assessed taking into account 9.9.7 and 9.10.3, respectively. 8.3 General provisions 8.3.1 When testing qualification, periodic, type, for type approval and for compliance with the approved type, separate tests that do not affect the results of other tests provided for in Table 12 are allowed to be carried out on different transformers (parallel tests). A list of parallel tests should be established in the standards for specific types of transformers. 8.3.2 It is allowed to combine certain types of tests listed in 8.1. If there are different versions of transformers, tests for type approval, qualification, periodic, type and for compliance with the approved type should be carried out on the type versions for which the corresponding tests are most critical. 8.3.3 Types and the number of transformers subjected to each test should be indicated in the standards for specific types of transformers. 8.3.4 During acceptance tests, transformers are presented for acceptance individually or in batches and subjected to continuous inspection. 8.3.5 Separate tests may be carried out on assembly units and parts of the transformer. It is allowed, by agreement between the consumer and the manufacturer, during qualification, periodic, type tests, for type approval and for compliance with the approved type, to count tests of transformers of other types that have similar design or technological solutions and the same materials used, if there are such instructions in the standards for transformers of specific types . 8.3.6 The sequence of tests can be arbitrary, unless other requirements are established in the standards for specific types of transformers. 8.3.7 If the results of acceptance, periodic and standard tests are negative after elimination of defects, repeated tests are carried out in full or, in technically justified cases, in a reduced scope: tests for which unsatisfactory results were obtained, tests that could have influenced the occurrence of defects are repeated, as well as tests that were not carried out. If specific reasons for an unsatisfactory result are not established, repeated tests on points of non-conformity are carried out on twice the number of samples. The results of repeated tests are final. 8.4 Qualification tests 8.4.1 The procedure for conducting qualification tests is in accordance with GOST 15.001 and GOST 15.309. 8.4.2 It is allowed to count as qualification tests tests of prototypes carried out in accordance with Table 12 if the following conditions are met: prototypes were manufactured using technology and equipment intended for mass production; During the manufacture of the installation series, no design modifications were carried out that required testing: the time elapsed after testing prototypes does not exceed the period established for periodic testing. If these conditions are not met, then, with appropriate technical justification, it is allowed to count tests whose results are not affected by non-compliance with the specified conditions. 8.5 Acceptance tests are carried out by the technical control service or another authorized service of the manufacturer. Simultaneously with acceptance tests, each transformer must undergo initial verification according to the rules adopted in the country of origin and the methodology in accordance with GOST 8.217. 8.6 Periodic testing 8.6.1 Periodic tests should be carried out on mass-produced transformers at least once every 5 years. Confirmation of average time to failure is carried out for the first time 10 years after the start of mass production, then at least once every 5 years. 8.6.2 If the production of transformers was interrupted by the time of the next periodic tests, then when production is resumed, periodic tests of transformers should be carried out on samples of the first batch manufactured after the resumption of production. Until the completion of individual (long-term) tests included in the scope of periodic tests, the basis for the release of transformers is the report of previous periodic tests. 8.7 Type tests should be carried out in full or a reduced scope of qualification tests when changing the design, materials used or production technology, if these changes may affect the characteristics or parameters of transformers. Depending on the nature of the change(s) being made, individual assembly units, parts, material samples, etc. may be subjected to testing. 8.8 Tests for type approval and for compliance with the approved type should be carried out according to the rules adopted in the country of manufacture. 9.1 Checking for compliance with the requirements of the assembly drawing 9.1.1 The following are subject to verification: overall 1), installation and connection dimensions, for which maximum deviations are indicated on the assembly drawing; transformer mass 1) ; surface condition of external insulating parts; condition of protective coatings of external parts; condition of areas for grounding clamps; correct filling of technical data plates; pin marking; completeness. The check is carried out by external inspection, measurement with a universal measuring tool, using templates, as well as weighing the transformer on a general-purpose scale or using a spring dynamometer. 1) Except for acceptance tests. 9.1.2 During acceptance tests, dimensions may be checked on parts and assembly units before assembling the transformer. 9.1.3 It is allowed to determine the mass of a transformer by summing the masses of its individual assembly units. 9.2 Insulation test 9.2.1 The insulation of the primary winding is tested: for transformers with a rated voltage of 0.66 kV - according to GOST 2933; for transformers with rated voltages from 3 to 500 kV inclusive - according to GOST 1516.1, GOST 1516.2 and GOST 1516.3; for transformers with a rated voltage of 750 kV - according to GOST 1516.2, GOST 1516.3 and GOST 20690. Test voltages are applied between one of the terminals (or short-circuited terminals) of the primary winding and the short-circuited terminals of the secondary windings to which the grounded parts of the transformer must be connected. For transformers that do not have their own primary winding, the method of applying voltage should be specified in the standards for the specific type of transformer. If there are no grounded elements in the transformer design, the standards for specific types of transformers must specify metal parts that must be connected to short-circuited secondary windings during testing. Methods for testing the insulation of oil-filled transformers for rated voltages of 330 kV and above with a chopped lightning impulse and multiple chopped impulses should be specified in the standards for specific types of transformers. 9.2.2 The length of the leakage distance of the external insulation of transformers for compliance with the requirements of 6.3.1 and 6.3.2 is checked according to GOST 9920. 9.2.3 Intersectional insulation is tested according to GOST 1516.2. A test voltage of 3 kV is applied alternately between each section and the other sections of the winding connected to each other. 9.2.4 The insulation of the secondary windings of transformers is tested according to GOST 1516.2. A test voltage of 3 kV is applied alternately between the short-circuited terminals of each of the secondary windings and the short-circuited terminals of the other secondary windings to which the grounded parts of the transformer are connected. If there are no grounded parts in the design, the instructions in 9.2.1 should be followed. 9.2.5 The level of partial discharges is determined according to GOST 1516.3 and GOST 20074. Methods for measuring the dielectric loss tangent of capacitor paper-oil insulation should be specified in the standards for specific types of transformers. 9.2.6 Turn-to-turn insulation test 9.2.6.1 When testing turn-to-turn insulation, the secondary winding under test must be open-circuited, and the remaining secondary windings (if any) must be short-circuited. A current with a frequency of 50 Hz is passed through the primary winding of the transformer, the value of which is determined in accordance with the requirements of 6.3.7 1). It is allowed to test with several simultaneously open secondary windings if comparative tests on the same installation prove that the voltage (amplitude) induced in the secondary windings does not decrease by more than 20% compared to tests carried out with one open winding. 1) The purpose of this test is not to reproduce the operating conditions of the transformer with the secondary circuit open, but to check the quality of the interturn insulation, therefore the current and voltage waveforms are not standardized. 9.2.6.2 The primary winding of busbar, bushing, built-in and plug-in transformers can be simulated by several turns, and the rated primary current is taken to be the value at which the value of the rated ampere turns is maintained. 9.2.6.3 The voltage induced in the secondary winding can be determined: by direct measurement of the voltage at the terminals of the tested secondary winding: for transformers that have their own primary winding, by measuring the voltage at the terminals of the primary winding and multiplying the measured voltage value by the ratio of the numbers of turns of the secondary and primary windings 2) ; for busbar, bushing, built-in and detachable transformers - by measuring the voltage at the terminals of the “control” winding, temporarily superimposed on top of the winding under test, and multiplying the measured voltage value by the ratio of the numbers of turns of the secondary and “control” windings. 2) In this measurement, the voltage drop across the primary winding is neglected. 9.2.6.4 Primary current (rms value) should be measured using a current transformer and an ammeter of accuracy classes not lower than 1. 9.2.6.5 The transformer is considered to have passed the test if during the test of the interturn insulation of the secondary windings there was no sharp increase in the primary current or a decrease in the induced voltage. The voltage induced in the secondary winding (amplitude value) should be determined with an error of no more than 10% using devices with high input resistance: an electronic voltmeter or a cathode-ray oscilloscope with a voltage divider. It is allowed to use a voltmeter to measure voltage, which responds to the amplitude value of the voltage, but is calibrated in the effective values of the sinusoidal curve. In this case, the voltage shown by the device must be multiplied by. It is allowed, instead of measuring current, to limit oneself to monitoring its change in the case when the determining quantity during testing is the amplitude value of the voltage, and, similarly, it is allowed, instead of measuring voltage, to limit oneself to monitoring its change in the case when the determining quantity during testing is the primary current. 9.2.7 Insulation tests carried out as a criterion for the success of other tests are carried out at test voltages equal to 90% of the rated values and an exposure time of 1 min, regardless of the type of insulation. 9.3 Measurement of the insulation resistance of the windings is carried out with a 2500 V megger for the primary windings and 1000 V for the secondary windings. 9.4 Determination of breakdown voltage and dielectric loss tangent when testing an oil sample - according to GOST 6581. For transformers with a rated voltage of up to 35 kV inclusive, an oil sample is taken on the test day from the container from which the oil was poured into the transformer, and for transformers with a rated voltage of 110 kV and above directly from the transformer. The sampling procedure should be established in the standards for specific types of transformers. Methods for determining moisture and gas content, as well as chromatographic analysis of gases contained in oil, must be specified in the standards for specific types of transformers. 9.5 Determination of errors 9.5.1 Checking polarity and determining current and angular errors 9.5.1.1 Polarity checks and determination of current and angular errors are carried out on transformers subjected to demagnetization. Demagnetization methods, polarity testing and error determination - according to GOST 8.217. The errors are determined on each secondary winding. If the winding is assigned several accuracy classes and (or) several loads, then during acceptance tests the determination of errors is carried out in the highest accuracy class under the conditions agreed upon between the manufacturer and the consumer, and for other types of tests - in all accuracy classes and at all loads established in standard for this transformer. 9.5.1.2 When determining errors in the secondary winding of a cascade transformer, all its other secondary windings must be closed to the loads. The percentage of load values to rated values shall correspond to the percentage of secondary load (to rated value) in the winding under test, unless otherwise specified in the standard for a particular type of transformer. 9.5.1.3 Errors of busbar, bushing, built-in and connector transformers during qualification, type and type approval tests should be determined in the primary current-carrying circuit according to Figure 1 a. 1
- transformer under test; A maximum distance between the axes of conductors of adjacent phases at the location where the transformer is installed in operation; B max - clear distance from the transformer to the place of the nearest bend of the conductor, which serves as the primary winding of the transformer in operation Picture 1 Numerical dimensions A max and B max should be established in the standards for transformers of a particular type and during testing they should not be exceeded. 9.5.1.4 Errors of busbar, bushing, built-in and connector transformers for rated currents over 2000 A during acceptance tests, periodic tests and for compliance with the approved type can be determined with a primary winding consisting of several turns, and with a correspondingly reduced value of the rated current (thus, so that the value of the nominal ampere-turns remains unchanged), if during qualification or type tests it is established that the difference in error values measured in a similar way and under the conditions of installation of the transformer in accordance with 9.5.1.3 does not exceed 25% of the rated values. The arrangement of the turns of the primary winding performed for testing, uniform along the magnetic core or concentrated on one of its parts, must be specified in the standard for the particular type of transformer. 9.5.2 If it is necessary to check the stability of metrological characteristics as a criterion for the success of other tests, it should be carried out by directly determining errors or measuring the magnetizing current in accordance with 9.13. The value of the permissible change in errors or magnetizing current must be established in the standard for a particular type of transformer. 9.5.3 During acceptance tests, errors can be measured at a smaller number of current values and loads than indicated in 6.4 (Tables 8 and 9), if this is justified by the results of qualification or type tests. 9.6 Checking the maximum multiplicity and safety factor of devices 9.6.1 Checking the maximum multiplicity and safety factor of devices should be carried out according to the scheme shown in Figure 2. TTO - exemplary current transformer; TTI - current transformer under test; TTPI - intermediate current transformer located in the circuit of the current transformer under test; TTPO - intermediate current transformer located in the circuit of the standard current transformer; A 1, A 2 - ammeters; Z 2 - secondary load in the circuit of the current transformer under test Figure 2 The following requirements apply to the circuit elements: a) transformation ratios of transformers TTPO and TTPI must be such that the condition is met where is the TTO transformation coefficient; TTPO transformation coefficient; TTI transformation coefficient; Transformation coefficient TTPI. If a model transformer has a transformation ratio at which the condition is met, then there may be no intermediate transformer in its circuit; b) ammeters A 1 and A 2 must measure effective current values. Ammeter A 2 should have low internal resistance. The accuracy class of ammeters must be at least 1. The accuracy class of intermediate transformers must be at least 0.5. An exemplary transformer must have: accuracy class not lower than 0.5 or total error not more than 0.5% when testing the secondary winding of class 5P; accuracy class not lower than 1 or total error not more than 1% when testing the secondary winding of class 10P; c) the load value and its power factor must be selected so that the total resistance of the external secondary circuit of the transformer under test (including the resistance of the wires and the intermediate transformer) and its power factor are equal to the specified values (with an accuracy of 5%). A current with a frequency of Hz of an almost sinusoidal shape is passed through the primary windings of the TTO and TTI, the value of which corresponds to the maximum multiplicity or safety factor of the devices. The primary current value is measured with an ammeter A 1. The total error ε, %, is determined by the formula where is the current according to the ammeter A 1, A; Ammeter current A 2, A. 9.6.2 If the test installation and (or) the standardized thermal resistance of the transformer under test limits the duration of the required current flow necessary to calm the ammeters, it is allowed to determine the current in another way, for example, by oscillography. For transformers with several nominal transformation ratios, obtained by switching winding sections at a constant value of the nominal ampere turns, the total error can be measured at any transformation ratio. 9.6.3 Busbar, bushing, built-in and plug-in transformers should be tested in a test circuit according to Figure 1 A. Numerical values of dimensions A and B must be established in the standards for specific types of transformers and when checking the maximum multiplicity they must not be exceeded, and when checking the safety factor of devices they must not be less than the established values. 9.6.4 The maximum multiplicity may be checked in another way, which must be established in the standard for a transformer of a particular type, if during qualification tests, type tests, for type approval or to check compliance with the approved type, it is proven that this method provides equivalent results. The safety factor of devices can be determined by measuring the magnetizing current according to 9.8.5. 9.7 Determination of quantitative gas leakage of gas-filled transformers 9.7.1 The leak detection test is carried out at a temperature of (25 ± 10) °C. The tested transformer, filled with gas to the nominal operating pressure, is placed in a closed volume (chamber, polymer film cover), which should not exceed the external volume of the tested transformer by more than 3 times. A fan is placed inside the volume to help mix the mixture of air and gas filling the transformer. After installing the transformer in a closed volume, insert the probe of a sensitive device (leak detector) that reacts to low concentrations of gas with which the transformer under test is filled, and record the readings of the device. After a certain period of time of keeping the transformer in a closed volume (for example, after 1 hour), the operation is repeated. For transformer filled with SF6 gas Notes 1 The volume values required to calculate leakage must be found with an error not exceeding 20%. 2 If the scale of the leak detection device is not directly calibrated to determine the concentration value, g/l, these values are found according to the dependence WITH = f(n), Where n- instrument readings in units of the scale attached to the certificate of certification (calibration), carried out in the prescribed manner. 9.8 Determination of magnetizing current of secondary windings 9.8.1 To determine the magnetizing current, a voltage is applied to the tested secondary winding with the primary winding open U frequency of 50 Hz and measure the current flowing through the winding. 9.8.2 Voltage value U, V, corresponding to the value of the primary current, A, is determined by the formula Where I K- the nominal safety factor of the winding for measurement or the nominal maximum factor of the winding for protection; R 2 - resistance of the secondary winding to direct current, reduced to the temperature at which the magnetizing current is determined, Ohm; Z 2nom - rated secondary load, Ohm. 9.8.3 Voltage U should be measured with a voltmeter. The voltmeter readings must be multiplied by a factor of 1.11. It is possible to carry out measurements with a voltmeter, the readings of which are proportional to the average voltage value, and the scale is graduated in the effective values of the sinusoidal curve. In this case, multiplying the voltmeter readings by a factor of 1.11 is not required. The main error of the voltmeter should be no more than ±1%. Voltage measurement U carry out: a) directly at the terminals of the secondary winding under test; b) for transformers that have their own primary winding - at the terminals of the primary winding. In this case, the voltmeter readings should be multiplied by a factor of 1.11 and by the ratio of the turns of the secondary and primary windings; c) for busbar, bushing, built-in and detachable transformers that do not have their own primary winding - at the terminals of a special “control” winding wound on the transformer for the duration of testing. In this case, the voltmeter readings should be multiplied by a factor of 1.11 and by the ratio of the turns of the secondary and “control” windings. 9.8.4 The effective value of the magnetizing current should be measured with an ammeter (milliammeter) of accuracy class no lower than 1. 9.8.5 Magnetizing current of secondary windings I 2us(%K), % is found by the formula Where I 2us - magnetizing current, A, measured according to 9.8.1; I 2nom - rated secondary current, A; K - K Bnom or K nom; I 2us(%K) - in accordance with the requirements of 6.5. 9.9 Heating test during continuous operation 9.9.1 Transformers for a rated voltage of 0.66 kV are tested according to GOST 2933, and for rated voltages from 3 to 750 kV inclusive - according to GOST 8024 at the highest operating primary current. Note- It is allowed to test transformers for a rated voltage of 0.66 kV in accordance with GOST 8024. 9.9.2 The test is carried out at normal test temperature in accordance with GOST 15150, unless other conditions are provided for in the standards for specific types of transformers. 9.9.3 When testing transformers that have their own primary winding, current should be supplied to the terminals of the primary winding with wires or busbars at least 1.5 m long. Transformers intended for operation with a specific type of busbar may be tested without taking into account the temperature of the conductors supplying current to the primary winding. In this case, the conductors supplying current during testing must comply with their operating conditions. 9.9.4 Busbar, bushing, built-in and detachable transformers are tested in the primary current-carrying circuit according to Figure 1 A or 1 b. The need for testing in the circuit, the type of circuit, as well as dimensions A max and B max (which must not be exceeded during testing) must be established in the standards for specific types of transformers. 9.9.5 Transformers with several transformation ratios obtained by switching sections of the primary winding are tested at the highest transformation ratio. 9.9.6 During testing, the secondary windings of transformers must be short-circuited to the rated load, to an ammeter or short-circuited. Hz by passing the following currents through the primary winding: a) current, the largest peak of which should be (1.0 - 1.1) i d 1) ; the initial effective value of the periodic component should not exceed the current flow time - 3-10 half-cycles, the number of experiments - 3; b) current I and, the effective value of which during the flow time t n must be such that the relation is satisfied In this case, the value t and should be from 0.5 to 5 s, the number of experiments is 1. If technically possible, tests according to transfers A And b can be combined. Before testing, the temperature of the transformer should be (25 ± 10) °C. 1) When testing busbar, bushing, built-in and detachable transformers, the value of the highest peak current is not set. 9.10.2 The test is carried out in a single-phase test circuit. The dimensions and configuration of the circuit when testing transformers of placement categories 2, 3, 4 and 5, as well as the distances from the terminals of the primary winding of the transformer to the nearest points of fixation of the circuit conductors must comply with those specified in the standards for specific types of transformers. Testing of busbar, bushing, built-in and detachable transformers can be carried out by simulating their primary winding with several primary turns, located evenly relative to the secondary windings. 9.10.3 The transformer is considered to have passed the test if: a) there has been no damage that would impede its further operation; b) after cooling to a temperature of (25 ± 10) °C, it passed the tests according to points 2, 10, 12 of Table 12; c) the errors of the secondary windings, measured after demagnetization, correspond to the established accuracy classes and have not changed compared to the original ones by more than half the values established for these classes. In the standards for transformers of specific types, in which the one-second current density of thermal resistance exceeds the following values: a) for transformers at a frequency of 50 Hz: 160 A/mm 2 - for copper conductors; 105 A/mm 2 - for aluminum conductors; b) for transformers at a frequency of 60 Hz: 154 A/mm 2 - for copper conductors; 101 A/mm 2 - for aluminum conductors Additional criteria must be established to confirm that the transformer has passed the short-circuit current tests. 9.11 Measurement of the resistance of secondary windings to direct current is carried out according to GOST 3484.1. 9.12 Oil-filled transformers are tested for leaks according to GOST 3484.5. 9.13 Methods and types of tests of transformers for resistance to climatic external influencing factors in accordance with GOST 16962.1 and mechanical external influencing factors in accordance with GOST 16962.2 must be specified in the standards for specific types of transformers, depending on the design and design features of the transformers. Metrological characteristics are checked using one of the following methods: a) by directly determining errors according to GOST 8.217 at the highest and lowest operating temperature values, taking into account long-term heating. In this case, current and angular errors should not exceed the values established in 6.4.2 for the corresponding accuracy classes; b) by measuring magnetizing currents in accordance with 9.8.5 at the highest and lowest operating temperatures, taking into account long-term heating. In this case, the value of the magnetizing current must meet the following conditions: where are the magnetizing currents at the highest and lowest operating temperatures, A; J 2nom - rated secondary current, A; f additional - limit of permissible current error, %; δ add - limit of permissible angular error, average. When testing transformers of placement category 1 for exposure to static test loads, the base of the transformer is rigidly fixed, and a test load equal to the value specified in 6.2.3 is applied to the middle of the terminal of its primary winding. The specified load is applied alternately in three mutually perpendicular directions: in the horizontal plane along the output axis away from the transformer, in the horizontal plane in the direction perpendicular to the output axis, in the vertical plane towards the base. In each direction the load holding time is 1 min. The transformer is considered to have passed the test if, during and after the test, there is no damage to the transformer or terminal, no oil leakage for oil-filled transformers, and no increase in gas leakage for gas-filled transformers. (Amendment, IUS 6-2007). 9.14 Transport strength test 9.14.1 Methods for testing strength during transportation according to GOST 23216 must be given in the standards for specific types of transformers. 9.14.2 After the test, the transformers are unpacked, an external inspection of the transformers, containers, fastenings is carried out, and the parameters established in the standards for specific types of transformers are checked. 9.14.3 The transformer and its packaging are considered to have passed the test if: During an external inspection of the packaging, no mechanical damage to the container was found, leading to a loss of protective properties, as well as violations of the fastenings of the packaged products in the container. It is allowed to loosen the fastenings of the product in the container if this does not lead to damage to the transformer during the test; During an external inspection of the transformer, no damage was found that would impede its operation, and the results of checking the parameters were positive. 9.14.4 When packing several transformers in one box, it is allowed to check the parameters selectively. The number of transformers to be tested should be specified in the standards for specific types of transformers. 9.14.5 For large-sized transformers, testing may not be carried out, and the ability of transformers and packaging to withstand the destructive effects of mechanical loads during transportation may be assessed based on the results of transporting these or similar products to the consumer. 9.15 Packaging drop test 9.15.1 Methods for testing transformer packaging for dropping according to GOST 18425 must be specified in the standards for specific types of transformers. 9.15.2 Packaging with a total mass (together with the packaged product) of up to 200 kg is subjected to testing. Packaging with a total weight of more than 200 kg, as well as packaging marked “Fragile. "Caution" is not subjected to the drop strength test. 9.15.3 The box (package) with the transformer(s) in it or a model simulating packaged transformers is dropped once onto the site in accordance with GOST 18425 on its end side from a height: 0.5 m - with a total mass of the transformer and packaging up to 100 kg inclusive; 0.3 m - with a total mass of the transformer and packaging from 100 to 200 kg inclusive. 9.15.4 At the end of the test, an external inspection of the packaging is carried out. 9.15 The packaging is considered to have passed the test if, upon external inspection, no serious damage leading to loss of its protective properties is detected. Loosening of individual fasteners is allowed. 9.16 Confirmation of average time to failure is carried out on the basis of collecting from consumers and processing information about the operation of transformers or their prototypes according to the methodology specified in the standard for a specific type of transformer. 9.17 Methods for testing gas-filled transformers for explosion safety should be specified in the standards for specific types of transformers. 10.1 Transport 10.1.1 Requirements for transportation in terms of exposure to mechanical factors in accordance with GOST 23216 and environmental climatic factors in accordance with GOST 15150 must be specified in the standards for specific types of transformers. When transported in transport containers, transformers without individual packaging must be securely fastened and protected from mechanical damage. It is allowed to transport transformers within the same city without packaging, provided that the necessary measures are taken to prevent the possibility of damage. 10.2 Storage 10.2.1 Requirements for the storage of transformers in terms of exposure to environmental climatic factors in accordance with GOST 15150 must be specified in the standards for specific types of transformers. When putting transformers into operation, as well as during the operation of transformers, the requirements established in the standards for specific types of transformers must be observed. These requirements must be specified in the operational documentation. 12.1 The manufacturer guarantees that transformers comply with the requirements of this standard subject to the conditions of use, operation, storage and transportation established by this standard. The warranty period for transformers is three years from the date of commissioning, but not more than three and a half years from the date of shipment from the manufacturer. 12.2 For transformers intended for export, the warranty period is established in accordance with the requirements adopted in the country of origin. The manufacturer's information materials should include the following reference data: a) permissible secondary loads for various accuracy classes, if such a requirement is provided for in the standard for a particular type of transformer; b) design data: the nominal number of ampere turns, the average length of the magnetic path and the cross-section of the magnetic core, the resistance of the secondary winding to direct current, the calculated value of the inductive reactance of the secondary windings (without taking into account the influence of external magnetic fields); c) typical magnetization curves of the magnetic circuits of the secondary windings for protection, taken at an almost sinusoidal voltage (dependence of the maximum induction on the effective value of the magnetic field strength); d) curves of the maximum multiplicity of secondary windings for protection for multiplicities not exceeding the dynamic withstand current divided by and for secondary loads - 25% of the rated value (but not less than 10 VA) and higher. For transformers with an asymmetrical arrangement of primary and secondary windings, the range of loads below the rated load may differ from the specified; e) design features of transformers. Note- Transfer data b - G are given for transformers with rated voltages of 6 kV and above (indicating the values of their possible deviations). Table B.1 Accuracy class Error 0,1; 0,2; 0,5; 1 Not standardized
UDC 621.314.224:006.354 Group E64
INTERSTATE STANDARD
CURRENT TRANSFORMERS General technical conditions
ISS 17.220.20
OKP 34 1440
Current transformers. General specifications
Date of introduction 2003-01-01
Preface
1 DEVELOPED by Open Joint Stock Company OJSC Sverdlovsk Current Transformer Plant
INTRODUCED by Gosstandart of Russia
2 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Protocol No. 20 of November 1, 2001)
The following voted for adoption:
State name
Gosstandart of the Republic of Kazakhstan
Kyrgyzstandard
Moldovastandard
Gosstandart of Russia
Tajikstandard
Main State Service "Turkmenstandartlary"
Uzgosstandart
State Standard of Ukraine
4 By Decree of the State Committee of the Russian Federation for Standardization and Metrology dated March 13, 2002 No. 92-st, the interstate standard GOST 7746-2001 was put into effect directly as the state standard of the Russian Federation from January 1
2003
5 INSTEAD GOST 7746-89
1 area of use
This standard applies to electromagnetic current transformers (hereinafter referred to as transformers) with a rated voltage from 0.66 to 750 kV inclusive, intended for transmitting a signal of measurement information to measuring, protection, automation, signaling and control devices in alternating current electrical circuits with a frequency of 50 or 60 Hz .
Additional requirements for certain types of transformers in connection with the specifics of their design or purpose (for example, for cascade transformers, transformers designed to operate with standardized accuracy in transient modes, for installation in complete switchgears (switchgear), phase-shielded current conductors) should be established in the standards , technical specifications, agreements or contracts (hereinafter referred to as standards) for specific types of transformers.
The standard does not apply to laboratory, zero-sequence, summing, blocking, and saturable transformers.
2 Normative references
This standard uses references to the following standards:
GOST 2.601-95 Unified system of design documentation. Operational documents GOST 8.217-87 State system for ensuring the uniformity of measurements. Current transformers. Verification method
GOST 12.2.007.0-75 System of occupational safety standards. Electrical products. General safety requirements
GOST 12.2.007.3-75 System of occupational safety standards. Electrical devices for voltages above 1000 V. Safety requirements
GOST 12.3.019-80 System of occupational safety standards. Electrical tests and measurements. General safety requirements
GOST 15.001-881) System for developing and putting products into production. Products for industrial and technical purposes
1) GOST R 15.201-2000 is in force in the Russian Federation.
GOST 15.309-98 System for developing and launching products into production. Testing and acceptance of manufactured products. Basic provisions
GOST 27.003-90 Reliability in technology. Composition and general rules for specifying reliability requirements
GOST 403-73 Electrical devices for voltages up to 1000 V. Permissible heating temperatures for parts of devices
GOST 1516.1-76 AC electrical equipment for voltages from 3 to 500 kV. Requirements for electrical insulation strength
GOST 1516.2-97 Electrical equipment and electrical installations of alternating current for voltage 3 kV and higher. General test methods for electrical insulation strength
GOST 1516.3-96 AC electrical equipment for voltages from 1 to 750 kV. Requirements for electrical insulation strength
GOST 2933-931) Low-voltage electrical devices. Test methods
1) GOST 2933-83 is in force in the Russian Federation.
GOST 3484.1-88 Power transformers. Electromagnetic Test Methods
GOST 3484.5-88 Power transformers. Tank leak testing
GOST 6581-75 Liquid electrical insulating materials. Electrical Test Methods
GOST 8024-90 Apparatuses and electrical devices for alternating current voltage
over 1000 V. Heating rate during continuous operation and test methods
GOST 9920-89 (IEC 694-80, IEC 815-86) AC electrical installations for voltage
from 3 to 750 kV. External insulation creepage distance
GOST 10434-82 Electrical contact connections. Classification. General technical
requirements
GOST 13109-97 Electrical energy. Electromagnetic compatibility of technical equipment. Standards for the quality of electrical energy in general-purpose power supply systems
GOST 14192-96 Marking of cargo
GOST 15150-69 Machines, instruments and other technical products. Versions for different climatic regions. Categories, operating, storage and transportation conditions regarding the impact of environmental climatic factors
GOST 15543.1-89 Electrical products. General requirements regarding resistance to climatic external influences
GOST 15963-79 Electrical products for areas with tropical climates. General technical requirements and test methods
GOST 16504-81 System of state testing of products. Testing and quality control of products. Basic terms and definitions
GOST 16962.1-89 (IEC 68-2-1-74) Electrical products. Test methods for resistance to climatic external influences
GOST 16962.2-90 Electrical products. Test methods for resistance to mechanical external influences
GOST 17516.1-90 Electrical products. General requirements regarding resistance to mechanical external influences
GOST 18425-73 Filled transport containers. Free fall impact test method
GOST 18685-73 Current and voltage transformers. Terms and Definitions
GOST 19880-74 Electrical engineering. Basic concepts. Terms and Definitions
GOST 20074-83 Electrical equipment and electrical installations. Method for measuring partial discharge characteristics
GOST 20690-75 AC electrical equipment for voltage 750 kV. Requirements for electrical insulation strength
GOST 21130-75 Electrical products. Grounding clamps and grounding signs. Design and dimensions
GOST 21242-75 Flat and pin contact terminals for electrical devices. Main Dimensions
GOST 23216-78 Electrical products. Storage, transportation, temporary anti-corrosion protection, packaging. General requirements and test methods
RMG 29-99 State system for ensuring the uniformity of measurements. Metrology. Basic terms and definitions
3 Definitions
The terms used in this standard and their corresponding definitions are according to RMG 29, GOST 16504, GOST 18685, GOST 19880, as well as the following:
3.1 nominal safety factor of devices: The ratio of the rated safety current of the devices to the rated primary current of the transformer.
3.2 rated safety current of devices: The minimum value of the transformer primary current at which the total error is at least 10% at the rated secondary load.
3.3 type approval test: A type of state metrological control of a newly developed transformer, carried out in order to ensure the uniformity of measurements, approve the type of transformer and enter it into the State Register of Measuring Instruments.
3.4 type approval test: A type of state metrological control carried out periodically in order to determine the conformity of transformers released from production to the approved type.
3.5 permissible error range: The area beyond which transformer errors should not extend.
4 Classification
4.1 Transformers are divided according to the following main characteristics:
4.1.1 By type of installation (location category and climatic version) according to GOST 15150. When placing transformers inside the shells of complete products, the placement categories must correspond to those indicated in Table 1.
Table 1 - Categories of placement of transformers installed inside the shells of complete products
also a special design.
4.1.3 By type of insulation: with cast insulation, with a porcelain cover, in a plastic case, with solid insulation (except porcelain and cast) or with a polymer cover, oil-filled, gas-filled.
4.1.4 According to the number of transformation stages: single-stage, cascade.
4.1.5 By the number of secondary windings: with one secondary winding, with several secondary windings.
4.1.6 According to the purpose of the secondary windings: for measurement and metering, for protection 1-1, for measurement and protection, for operation with standardized accuracy in transient modes.
1- Hereinafter, the word “protection” means protection, automation, control and alarm.
4.1.7 By the number of transformation ratios: with one transformation ratio, with several transformation ratios obtained by changing the number of turns of the primary and/or secondary windings, as well as by using several secondary windings with different numbers of turns, corresponding to different values of the rated secondary current.
4.1.8 Features according to 4.1.2, 4.1.3, 4.1.4, 4.1.6 and their designations are given in tables 2 - 4.
table 2
Transformer design
Type of insulation
General technical conditions
ON STANDARDIZATION, METROLOGY AND CERTIFICATIONPreface
1 area of use
2 Normative references
3 Definitions
4 Classification
5 Basic parameters
Parameter name
2nom with power factor cos φ 2 = 1, VA
2nom with inductive-active power factor cos φ 2 = 0.8 VA 1)
6 Technical requirements
7 Safety requirements
8 Acceptance rules
9 Control methods
10 Transportation and storage
11 Operating instructions
12 Manufacturer's warranty
APPENDIX A
(required)List of reference data provided in the information materials of the manufacturer
APPENDIX B
(required)Permissible error range for transformers of various accuracy classes
