Some standard content:
ICS17.220.20
National Standard of the People's Republic of China
GB/T4703—2001
eqyIEc60186:1987
Capacitor voltage transformer
Capacitor voltage transformers2001-11-02 Issued
People's Republic of China
General Administration of Quality Supervision, Inspection and Quarantine
2002-06-01 Implementation
GB/T 4703—2001
IECForeword
Cited standards
Product classification
Technical requirements
Test methodsbzxZ.net
Inspection rules
Marking…
Safety requirements
Appendix A (Appendix to the standard)
Appendix B (Appendix to the standard)
Appendix C (Appendix to the standard)
Main conditions for allowing tests on equivalent circuitsLoad for transient response tests
Conditions for using equivalent circuits in accuracy tests 12
GB/T4703—2001
This standard equivalently adopts the international standard IEC60186:1987 "Voltage transformers" and its first amendment (1988). This standard is coordinated and consistent with relevant standards.
This standard is a revision of GB/T4703-1984 "Capacitor Voltage Transformer". The main technical contents have the following changes: 1) 35kV and 66kV are listed in the rated voltage level of transformer products. 2) The ferromagnetic resonance test refers to the draft of IEC60044-5 and my country's experience to add 0.8UiN and 1.0U,v tests, and modify the number of tests and transition process time.
3) The performance requirements and test methods of the transformer's ability to withstand short circuits are added. 4) The method of applying load to each winding at the same time in the accuracy test when the transformer has two or more secondary windings is clearly stipulated. 5) According to the first revision (1988) of IEC60186:1987, the definition of thermal limit output, the standard value of rated thermal limit output and the corresponding content in the temperature rise test are added.
6) The product withstand test voltage and the corresponding nominal creepage distance of different pollution migration levels are included in this standard. The numerical values are consistent with GB311.1 and GB/T5582.
7) Safety requirements in Chapter 9 are added.
Appendix A, Appendix B and Appendix C of this standard are all appendices of the standard. This standard is proposed by the China Electrical Equipment Industry Association. This standard is under the jurisdiction of the National Technical Committee for Standardization of Power Capacitors. The drafting units of this standard are: Xi'an Power Capacitor Research Institute and Guilin Power Capacitor General Factory. The main drafters of this standard are: Fang Jinlan, Li Zhaoyi and Guo Tianxing. This standard is entrusted to the National Technical Committee for Standardization of Power Capacitors for interpretation. GB/T4703—2001
IEC Foreword
1) The formal resolutions or agreements of the IEC on technical issues formulated by the technical committees of all national committees that are particularly concerned about the issue express the international consensus on the issues involved as much as possible. 2) These resolutions or agreements are used internationally in the form of recommendations and are accepted by the national committees in this sense. 3) In order to promote international unification, the IEC national committees agree to adopt IEC recommended standards as much as possible in their national and regional standards. Any differences between IEC recommended standards and corresponding national or regional standards shall be clearly indicated in the latter. 4) IEC has not established any procedures for indicating approval marks. IEC is not responsible for any claim that a certain equipment complies with an IEC standard.
This standard was prepared by IEC Technical Committee 38 "Transformers". This second edition of the standard replaces IEC60186:1969, the first edition, as well as Supplement A (1970), Supplement B (1981), Amendment No. 1 (1978) and Amendment No. 2 (1980). The text of this standard is based on the following documents: Six-month method
38 (Central Office) 69
Voting report
38 (Central Office) 71
Detailed information can be found in the relevant voting report shown in the table above. This standard refers to the following IEC publications:
60028:1925
Publication
International Standard for Steel Resistance
60038.1983
IEC Standard Voltage
Two-Month Procedure
38 (Central Office) 73
60044-4:1980 Instrument Transformers Part 4: Partial Discharge Measurement 60050 (321):1986 International Electrotechnical Vocabulary (IEV) Chapter 321: Instrument Transformers 60060 High Voltage Test Techniques
Voting Report
38 (Central Office) 73 76
60060-1:1973 High voltage test technology Part 1: General terms and test requirements 60071 Insulation coordination
60085:1984
Thermal evaluation and classification of electrical insulation
Coupling capacitors and capacitive voltage dividers
60358:1971
Artificial pollution transfer test for high voltage insulators for AC systems: 60507:1975
1 Scope
National Standard of the People's Republic of China
Capacitor voltage transformer
Capacitor Voltage transformersGB/T4703-2001
eqvIEC60186:1987
Replaces GB/T4703-1984
This standard specifies the scope of application, terminology, product classification, technical requirements, test methods, inspection rules, marking and safety requirements of capacitor voltage transformers.
This standard applies to single-phase capacitive voltage transformers (hereinafter referred to as "transformers") connected between the line and the ground to provide voltage signals for electrical measuring instruments, meters, protection and control devices in AC power systems with a frequency of 50Hz or 60Hz. This transformer can also be used as a coupling capacitor for power line carrier communication systems. This standard does not apply to transformers with a rated output lower than 10VA. 2 Reference standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB311.1-1997 Insulation coordination of high-voltage transmission and transformation equipment (negIEC60071-1:1993) GB1207-1997 Voltage transformer (e qvIEC60186:1987) GB/T5582-1993 External insulation pollution migration level of high-voltage power equipment (neqIEC60815:1986 and IEC60507:1991) GB/T16927.1-1997 High voltage test technology Part: General test requirements (eqv1IEC60060-1:1989) JB/T8169--1999 Coupling capacitors and capacitive voltage dividers (eqvIEC60358:1990) 3 Terms
3.1 Capacitor voltage transformer capacitorvoltagetransformer A voltage transformer composed of a capacitor voltage divider and an electromagnetic unit. 3.2 Capacitor voltage transformer for use with measurement electricalmeasuringinstrument
Capacitor voltage transformer used to provide voltage signals for measuring instruments and meters. 3.3 Capacitor voltage transformer for use with protectivedevice Capacitor voltage transformer used to provide voltage signals for relay protection and control devices. 3.4 Maximum voltage forequipment (U.) The highest voltage forequipment (U.) The root mean square value of the highest phase-to-phase voltage on which the insulation design of the transformer is based. This voltage should be equal to or higher than the maximum voltage of the system. 3.5 Rated primary voltage (Ui) ratedprimaryvoltage (U) The primary voltage value specified in the design as the performance benchmark of the transformer. 3.6 Rated secondaryvoltage The secondary voltage value specified in the design as the performance benchmark of the transformer. 3.7 Rated transformation ratio ratedtransformationratio Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on November 2, 2001 and implemented on June 1, 2002
GB/T4703—2001
The ratio of the rated primary voltage to the rated secondary voltage of the transformer. 3.8 Actual transformation ratio actualtransformationratio The ratio of the actual primary voltage to the actual secondary voltage of the transformer. 3.9 Voltage error (ratio error) voltageerror (ratioerror) The voltage measurement error caused by the actual transformation ratio of the transformer not being equal to the rated transformation ratio. The voltage error is expressed by the following formula: Voltage error = × 100%
Rated transformation ratio:
Where: KN
U,—-actual primary voltage,
U2——actual secondary voltage when U, is applied under measurement conditions. (1
3.10 Phase difference phasedisplacement
The phase angle difference between the primary voltage phasor and the secondary voltage phasor of the transformer. If the secondary voltage phasor leads the secondary voltage phasor, the phase difference is positive.
accuracyclass
3.11 Accuracy class
The error class given to the transformer. Under the specified conditions of use, the measurement error of the transformer should be within the limit corresponding to its accuracy class.
3.12 Burden
The admittance of the transformer secondary circuit.
The load is usually expressed as the apparent power value at the specified power factor and rated secondary voltage.1
2 A damping device as one of the transformer components The apparent power provided should not be taken into account in the load of the transformer. 3.13 Rated load ratedburden
The specified load value corresponding to the accuracy class of the transformer. 3.14 Rated output ratedoutput
The apparent power (expressed in volt-amperes) provided by the transformer to the secondary circuit connected to the rated load at the rated secondary voltage. 3.15 Thermal limiting output thermallimitingoutput The apparent power (expressed in volt-amperes) based on the rated voltage that can be provided by its secondary winding under the condition that the temperature rise of the transformer does not exceed the limit.
1 In this case, the error limit may be exceeded. 2 When there are multiple secondary windings, their thermal limit outputs should be marked separately. 3 Unless otherwise specified, two or more secondary windings are not allowed. The secondary winding also supplies the thermal limit output. 3.16 Rated frequency (fn) ratedfrequency (f) The frequency on which the technical requirements of this standard for transformers are based. 3.17 Rated capacitance (C) ratedcapacitance (CN) The capacitance between the high-voltage terminal and the low-voltage terminal specified in the design of the capacitor divider. 3.18 Rated voltage factor ratedvoltagefactor The ratio of the highest voltage that the transformer can meet the corresponding thermal performance and accuracy requirements within the specified time to the rated primary voltage. 3.19 Capacitor divider capacitordivider A voltage divider composed of capacitors.
3.20 High-voltage (or line) terminal high-voltage (or line) term inal Terminals used to connect to transmission lines or busbars. 3.21 Low-voltage terminal low-voltageterminal Terminals used to connect to carrier coupling devices or grounding. 2
GB/T4703—2001
3.22 Intermediate-voltageterminal Terminals that draw voltage proportionally from the capacitor voltage divider for connection to the electromagnetic unit. 3.23 Primary terminal primaryterminal
General term for high-voltage terminals and grounding terminals.
3.24 High-voltage capacitor (C) high-voltagecapacitor (C) Capacitor connected between the high-voltage terminal and the medium-voltage terminal in the capacitor voltage divider. 3.25 Medium-voltage capacitor (C,) intermediate-voltagecapacitor (C,) Capacitor connected between the medium-voltage terminal and the low-voltage or grounding terminal in the capacitor voltage divider. 3.26 Electromagnetic unit electromagneticunit A component of a capacitive voltage transformer that generates a secondary voltage by electromagnetic induction between the medium-voltage terminal of the capacitor voltage divider and the grounding terminal or ground.
Note: The electromagnetic unit usually consists of a medium-voltage transformer, a reactor and other accessories. 3.27 Secondary winding secondarywinding is a winding that provides voltage signals for the voltage circuit of measuring instruments, meters and protection and control devices. 3.28 Residual voltage winding residual voltagewinding is a secondary winding intended to be connected into an open triangle in a three-phase mutual inductor group to generate residual voltage in the event of a ground fault. 3.29 Intermediate voltage intermediatevoltage The voltage between the medium-voltage terminal of the voltage divider and the ground. 3.30 Voltage divider ratio voltageratio
When no impedance is connected in parallel to the medium-voltage capacitor, the ratio of the voltage applied between the high-voltage terminal and the low-voltage terminal of the capacitor voltage divider to the intermediate voltage. The numerical value is equal to (C, +C2)/Cr.
3.31 Rated voltage divider ratio ratedvoltageratio The voltage divider ratio when both the high-voltage capacitor and the medium-voltage capacitor have rated capacitance values. 3.32 Rated open-circuit intermediate voltage ratedopen-circuitintermediatevoltage The voltage on the medium-voltage capacitor without parallel impedance when both the high-voltage capacitor and the medium-voltage capacitor of the capacitive voltage divider have rated capacitance and the voltage applied between the high-voltage terminal and the low-voltage terminal is the rated value. 3.33 Permissible rangeoffrequency The frequency range in which the transformer meets the requirements of the relevant accuracy level. 3.34 Permissible rangeoftemperature The ambient temperature range in which the transformer meets the requirements of the relevant accuracy level. 3.35 Temperature categorytemperaturecategry The type of environmental source temperature expressed by the lower limit temperature (minimum ambient temperature) at which the transformer can be put into operation and the upper limit temperature (maximum ambient temperature) at which the transformer can operate continuously.
3.36 Protective deviceprotectivedevice A device in the transformer used to limit the overvoltage that may appear on one or more components or a device used to prevent positive and continuous ferromagnetic resonance.
3.37 Carrier-frequency coupling device is connected between the capacitor voltage divider and the carrier device, and can transmit the carrier frequency signal between the transmission line and the carrier device together with the capacitor voltage divider.
4 Product classification
4.1 Ambient air temperature category
The ambient air temperature range of the transformer installation and operation area is -50°C to +55°C. Within this temperature range, it is divided into several temperature categories according to the ambient air temperature range that the transformer can adapt to 3
GB/T 4703-2001
. Each temperature category is represented by the lower limit temperature value and the upper limit temperature letter code separated by a slash.
The lower limit temperature is selected from the five values of +5°C, -5°C, -25°C, -40°C and -50°C. The provisions of the upper limit temperature letter code are shown in Table 1. Table 1 Upper limit of ambient air temperature
Letter code
Note: The temperature values in the table can be obtained from meteorological data. Upper limit of ambient air temperature
24h average maximum
Annual average maximum
Any lower limit temperature and upper limit temperature can form a temperature category. The preferred temperature categories are: -40/A, -25/B and -5/C.
4.2 System conditions
According to the grounding conditions of the power system, the transformer is divided into the following two types: a) Transformer for neutral point effective grounding system: b) Transformer for neutral point non-effective grounding system. 4.3 Rated voltage
4.3.1 Rated primary voltage (Uin)
The rated primary voltage of the transformer shall comply with the provisions of Table 2. Table 2 Rated primary voltage (root mean square value)
System maximum voltage
Equipment maximum voltage U.
Rated primary voltage of transformer UiN
Note: Other rated primary voltage values can be used according to user requirements. 4.3.2 Rated secondary voltage
110//3
220//3
The rated voltage of the secondary winding for measurement and protection of the transformer should be 100/V3V. The rated voltage of the residual voltage winding of the transformer: a) It should be 100V for the neutral point effectively grounded system; b) It should be 100/3V for the neutral point non-effectively grounded system. Note: Other rated secondary voltage values can be used according to user requirements. 4.4 Rated voltage factor
330/V3
The rated voltage factor is related to the grounding method of the neutral point of the power system to which the transformer is applicable, and its standard value is shown in Table 3. Table 3 Rated voltage factor
Rated voltage factor
Allowable operating time
System grounding method
Neutral point effective grounding system
500//3
Neutral point non-effective grounding system with automatic cut-off protection against ground faults
Rated voltage factor
GB/T4703—2001
End of Table 3)
Allowable operating time
1 The allowable operating time listed in the table can be changed through consultation between the user and the manufacturer. System grounding method
Neutral point non-effective grounding system without automatic cut-off protection against ground faults
2 The "rated voltage factor" involved in the following contents of this standard refers to the value under non-continuous operation. 4.5 Rated output
When the rated secondary voltage and load power factor of the transformer are 0.8 (lagging), the rated output standard values of the secondary winding are: 10, 15, 25, 30, 50, 75, 100, 150. 200, 300, 400, 500VA. Among them, the values with a subscript dash are the priority values.
4.6 Rated thermal limit output
When the rated secondary voltage and load power factor of the transformer are 1, the rated thermal limit output standard values of the secondary winding are: 20, 25, 50.75, 100, 150VA and their multiples of 10 or 100. Among them, the values with a subscript dash are the priority values.
The rated thermal limit output of the residual voltage winding is based on a duration of 8h. 5 Technical requirements
5.1 Usage requirements
5.1.1 Installation and use location
Outdoor.
5.1.2 Altitude
The altitude of the installation and operation area shall not exceed 1000m. Note: According to user requirements, transformers suitable for areas above 1000m above sea level can be manufactured. 5.1.3 Wind speed
The wind speed in the installation and operation area shall not exceed 150km/h. 5.1.4 Pollution migration
The atmospheric pollution migration degree in the installation and operation area is divided into four levels. The recommended values of the nominal creepage distance of the external insulation of the transformers suitable for different pollution migration levels (calculated based on the highest voltage U. of the equipment) are listed in Table 4. The rest shall comply with the provisions of GB/T5582. Table 4 Nominal creepage distance classification
Pollution migration level
Nominal creepage distance/mm/kV
5.1.5 Earthquake
The seismic fortification degree in the installation and operation area shall not exceed 8 degrees. 5.2 Performance and structural requirements
5.2.1 Appearance requirements
The exposed surface of the metal parts of the transformer should have a good anti-corrosion layer, and the product nameplate and terminal markings should meet the requirements of the drawings. 5.2.2 Sealing performance
The transformer should have good sealing performance. 5.2.3 Accuracy level
The measurement accuracy level is nominally specified by the maximum allowable voltage error percentage under specified operating conditions. The protection accuracy level is nominally specified by adding a letter "P" after the maximum allowable voltage error percentage under specified operating conditions. All secondary windings for protection, except for the residual voltage winding, should also be given GB/T4703--2001
Measurement accuracy level.
Note: If the residual voltage winding is used for other special purposes, the measurement accuracy level can be given after consultation between the user and the manufacturer. The standard accuracy level, the corresponding error limit and the specified operating conditions are shown in Table 5. At 2% rated voltage, the error limit of the protection accuracy level is twice the error limit at 5% rated voltage. When the carrier coupling device is connected to the low-voltage terminal of the capacitive voltage divider by the transformer manufacturer, the transformer should still be able to ensure that it meets the accuracy level requirements.
5.2.4 Insulation level
The insulation between the high-voltage terminal and the grounding terminal of the transformer should be able to withstand the withstand voltage listed in Table 6. Table 5 Accuracy level
Error limit
Operating conditions
Voltage error/%
Phase difference/()
Voltage/%
Allowable frequency range/%
Allowable temperature range
Load/%
Load power factor
Measurement accuracy level
80~120
Not specified
992101
Lower limit to upper limit temperature of temperature category
25~100
0.8 (hysteresis)
The values in brackets are applicable to transformers used in systems with non-effectively grounded neutral points. Protection accuracy level
5~150 or 5~190)
96~102
When there are multiple separate secondary windings, due to the mutual influence between them, each winding should meet its own accuracy level requirements within the range of 25%~100% of its rated output. At this time, other secondary windings should carry a load corresponding to 0~100% of their rated output. For measurement accuracy, if a winding has only occasional short-term loads or is used as a residual voltage winding, its influence on other windings can be ignored.
When a mutually inductive secondary winding is used for measurement and protection at the same time, the measurement and protection accuracy level and rated output of the secondary winding should be marked. Table 6 Insulation Withstand Voltage
Rated Primary Voltage of Transformer
110/V3
220/V3
330/V3
Rated Short-Duration Power Frequency Withstand Voltage
Root Mean Square Value
80/95)
185/200m
1) The data under the slash line is the withstand voltage of the external insulation. Rated Electrical Impulse Withstand Voltage
185/2002)
450/4802)
Rated Operation Impulse Withstand Voltage
2) The data under the slash line is only for internal insulation. Note: For those with two insulation levels for the same rated voltage, the grid structure and overvoltage level, the configuration and performance of the overvoltage protection device, and the acceptable insulation failure rate should be considered when selecting. 6
GB/T4703--2001
The insulation of the medium-voltage circuit of the electromagnetic unit shall be able to withstand the voltage calculated by the following formula: C
U.=Uu×c+c×
Where: U——test voltage between the high-voltage terminal and the grounding terminal of the transformer; Ci.C\-represents the high-voltage capacitor and the medium-voltage capacitor of the capacitor voltage divider; K—voltage distribution unevenness coefficient, which can be taken as 1.05. ... (2)
The insulation level between the terminals of the reactor winding and the discharge voltage of its protective device shall be consistent with the maximum overvoltage level that may occur on the reactor during the short circuit and disconnection of the secondary side. The specific value shall be specified by the manufacturer. If an overvoltage protection device is connected between the medium-voltage terminal and the ground, its discharge voltage shall be specified by the manufacturer. The insulation between the grounding terminal and the ground of the medium-voltage circuit of the electromagnetic unit, and between the terminals of the secondary winding (including accessories) and the ground and each other shall be able to withstand a test voltage of 3kV (root mean square value) at the power frequency for 1 minute. The insulation of the low-voltage terminal of the capacitor voltage divider to the ground should be able to withstand a test voltage of 10kV (root mean square value) at the power frequency for 1 minute. If the low-voltage terminal is not exposed to wind and rain, the test voltage is 4kV (root mean square value).
5.2.5 Ferromagnetic resonance
When the voltage is 0.8UiN, 1.OU and 1.2Ui~ and the load is actually zero, the secondary terminal of the transformer is short-circuited and then the short circuit is suddenly eliminated. The secondary voltage peak should recover to a voltage value that is not more than 10% different from the normal value within 0.5s. When the voltage is 1.5U (for neutral point effective grounding system) or 1.9U (for neutral point non-effective grounding system) and the load is actually zero, the secondary terminal of the transformer is short-circuited and then the short circuit is suddenly eliminated. The duration of ferromagnetic resonance should not exceed 2s. 5.2.6 Transient response
After the high voltage terminal of the transformer is short-circuited to the ground terminal at rated voltage, the secondary output voltage shall decay to less than 10% of the voltage value before the short circuit within one cycle of rated frequency. Note: The influence of transient response on the protection action of the power grid is a very complex issue, and it is impossible to give a value that is valid for every situation. The influence on the relay is not only related to the amplitude of the transient process, but also to its frequency. The above given values can enable ordinary electromechanical protection relays to operate correctly under normal line lengths and short-circuit currents. For fast relays (such as solid-state relays), or very short lines, or when the short-circuit current is very small, the transient response can be negotiated by the user with the manufacturer of the protection relay and transformer, and more stringent requirements (such as less than 5%) can be proposed.
5.2.7 Polarity relationship
Terminals marked with the same letter in uppercase and lowercase should have the same polarity at the same moment, which is called subtractive polarity. 5.2.8 Short-circuit Withstand Capacity
Under rated primary voltage, the transformer shall be able to withstand the mechanical and thermal effects of a secondary short circuit lasting 1s without damage. 5.2.9 Temperature Rise Limit
Under specified voltage, rated frequency and specified load, when the power factor of the load is any value between 0.8 (lagging) and 1, the temperature rise of each winding of the electromagnetic unit of the transformer shall not exceed the following specified values: a) Regardless of its rated voltage factor and allowed operating time, the electromagnetic units of all transformers shall be tested continuously under the conditions of 1.2 times the rated voltage with the secondary winding connected to the rated load (if there are multiple rated load values, the largest one shall be taken) and the residual voltage winding not connected to the load until the temperature reaches stability. If the thermal limit output is specified, the electromagnetic unit shall also be tested under the rated primary voltage and the load corresponding to its thermal limit output and a power factor of 1. If the thermal limit output is specified for one or more secondary windings, they shall be tested separately. Unless otherwise specified, only one secondary winding shall be connected to a load corresponding to its thermal limit output and with a power factor of 1 in each test. At this time, the other secondary windings shall not be connected to a load.
The temperature rise of each winding shall not exceed 60°C.
b) For transformers with a rated voltage factor of 1.5 (or 1.9) and an allowable operating time of 30s, the electromagnetic unit shall be immediately subjected to a 1.5 (or 1.9) times rated voltage (at this time, the secondary winding and the residual voltage winding 7
GB/T4703-2001
should be connected to the maximum rated load) after the temperature rise test at 1.2 times rated voltage in item a) reaches a stable state, and the temperature rise of each winding shall not exceed 70°C for 30s. This test can also be started from the cold state, and the temperature rise of each winding shall not exceed 10°C.
Note: If other methods can be used to prove that the transformer meets this requirement, this test may not be carried out. c) For the transformer with a rated voltage factor of 1.9 and an allowable operating time of 8h, the electromagnetic unit shall be immediately subjected to a 1.9 times rated voltage after reaching a stable state under the temperature rise test of 1.2 times rated voltage in item a) (at this time, the secondary winding shall be connected to the maximum rated load, and the residual voltage winding shall be connected to the rated load or thermal limit load), and the temperature rise of each winding shall not exceed 70℃. Under the above test conditions, the temperature rise of the core and other metal parts of the electromagnetic unit and the oil top layer shall not exceed 50℃. 5.2.10 Grounding bolt and grounding symbol
The transformer shall have a grounding bolt with a diameter of not less than 8mm, or other parts for grounding wire connection, such as a grounding plate with sufficient area and connection holes). The grounding point shall have a flat metal surface and be marked with a clear grounding symbol "-" next to it. The grounding parts shall have a reliable anti-rust coating or be made of stainless steel. 5.2.11 Capacitor voltage divider
The capacitor voltage divider in the transformer shall comply with the provisions of JB/T8169. 5.2.12 Protective gap of carrier coupling device If a protective gap is installed between the low-voltage terminal and the grounding terminal of the capacitive voltage divider of the transformer, its power frequency discharge voltage shall not be greater than 2kV (root mean square value).
6 Test method
6.1 Test conditions
The factory test and type test of the transformer shall be carried out under the following conditions, except for those specified in the relevant standards and relevant clauses of this standard:
a) The ambient air temperature is +5~+35°C, and the temperature of the test piece shall not be significantly different from the ambient air temperature. After the test piece is placed in a constant ambient air temperature for a suitable long time without power, it is considered to be the same as the ambient air temperature. b) The power frequency voltage waveform used in the test shall comply with the provisions of GB/T16927.1, and the frequency is (0.91.1)fn. 6.2 Test of capacitive voltage divider
Except as specified in this standard, the test of capacitive voltage divider shall be carried out in accordance with JB/T8169. 6.3 Sealing test
The sealing test method of the electromagnetic unit shall be specified by the manufacturer. 6.4 Polarity test of winding
The polarity test of the electromagnetic unit winding is generally carried out by the DC method. 6.5 Withstand voltage test
Except for the following provisions, the rest shall be carried out in accordance with the relevant provisions of GB/T16927.1. 6.5.1 Withstand voltage test between primary terminals The test voltage is applied between the high voltage terminal and the grounding terminal (the low voltage terminal is connected to the grounding terminal). The short-time power frequency withstand voltage test (thousand test and wet test) is carried out on the capacitor voltage divider and the electromagnetic unit respectively. The test method of the electromagnetic unit is shown in 6.5.4.
The lightning impulse withstand voltage test is preferably carried out on the transformer as a whole, and the waveform of the test voltage is (1.2~5)/(40~~60)μs. Alternatively, it is carried out on the capacitor voltage divider and the electromagnetic unit respectively, and the test voltage of the electromagnetic unit is calculated according to formula (2). The switching impulse withstand voltage test (wet test) is preferably carried out on the transformer as a whole, with the test voltage waveform being 250/2500μS. Alternatively, it can be carried out only on the capacitor voltage divider, while the electromagnetic unit is assessed by the above-mentioned short-time power frequency withstand voltage test. During the lightning impulse withstand voltage test and the switching impulse withstand voltage test, positive and negative polarity impulses should be applied 15 times each. If no more than 2 flashovers and no breakdown occur in 15 consecutive impulses, the transformer is considered to have passed the test. 6.5.2 Power frequency withstand voltage test of the low-voltage terminal of the capacitor voltage divider to the ground 89 times the rated voltage (at this time, the secondary winding should be connected to the maximum rated load, and the residual voltage winding should be connected to the rated load or thermal limit load), for 8 hours, the temperature rise of each winding should not exceed 70℃. Under the above test conditions, the temperature rise of the core and other metal parts of the electromagnetic unit and the oil top layer should not exceed 50℃. 5.2.10 Grounding bolt and grounding symbol
The transformer should have a grounding bolt with a diameter of not less than 8mm, or other parts for grounding wire connection, such as a grounding plate with sufficient area and connection holes). The grounding point should have a flat metal surface and be marked with an obvious grounding symbol "一" next to it. The grounding parts should have a reliable anti-rust coating or be made of stainless steel. 5.2.11 Capacitor voltage divider
The capacitor voltage divider in the transformer should comply with the provisions of JB/T8169. 5.2.12 Protective gap of carrier coupling device If a protective gap is installed between the low-voltage terminal and the grounding terminal of the capacitor voltage divider of the transformer, its power frequency discharge voltage should not be greater than 2kV (root mean square value).
6 Test methods
6.1 Test conditions
The factory test and type test of the transformer shall be carried out under the following conditions, except for those specified in the relevant standards and the relevant clauses of this standard:
a) The ambient air temperature is +5~+35°C, and the temperature of the test piece shall not be significantly different from the ambient air temperature. After the test piece has been placed in a constant ambient air temperature for a suitable period of time without power, it is considered to be the same as the ambient air temperature. b) The power frequency voltage waveform used in the test shall comply with the provisions of GB/T16927.1, and the frequency is (0.91.1)fn. 6.2 Test of capacitor voltage divider
Except for the provisions of this standard, the test of capacitor voltage divider shall be carried out in accordance with JB/T8169. 6.3 Sealing test
The sealing test method of the electromagnetic unit shall be specified by the manufacturer. 6.4 Polarity test of winding
The polarity test of the electromagnetic unit winding is generally carried out by the DC method. 6.5 Withstand voltage test
Except for the following provisions, the rest shall be carried out in accordance with the relevant provisions of GB/T16927.1. 6.5.1 Withstand voltage test between primary terminals The test voltage is applied between the high voltage terminal and the grounding terminal (the low voltage terminal is connected to the grounding terminal). The short-time power frequency withstand voltage test (thousand-time test and wet test) is carried out on the capacitor voltage divider and the electromagnetic unit respectively. The test method for the electromagnetic unit is shown in 6.5.4.
The lightning impulse withstand voltage test is preferably carried out on the transformer as a whole, and the waveform of the test voltage is (1.2~5)/(40~~60)μs. Alternatively, it is carried out on the capacitor voltage divider and the electromagnetic unit respectively, and the test voltage of the electromagnetic unit is calculated according to formula (2). The switching impulse withstand voltage test (wet test) is preferably carried out on the transformer as a whole, and the waveform of the test voltage is 250/2500μS. Alternatively, it is carried out only on the capacitor voltage divider, and the electromagnetic unit is assessed by the above-mentioned short-time power frequency withstand voltage test. During the lightning impulse withstand voltage test and the switching impulse withstand voltage test, positive and negative impulses shall be applied 15 times each. If no more than 2 flashovers and no breakdown occur in 15 consecutive impulses, the transformer is considered to have passed the test. 6.5.2 Power frequency withstand voltage test of the low voltage terminal of the capacitor voltage divider to the ground 89 times the rated voltage (at this time, the secondary winding should be connected to the maximum rated load, and the residual voltage winding should be connected to the rated load or thermal limit load), for 8 hours, the temperature rise of each winding should not exceed 70℃. Under the above test conditions, the temperature rise of the core and other metal parts of the electromagnetic unit and the oil top layer should not exceed 50℃. 5.2.10 Grounding bolt and grounding symbol
The transformer should have a grounding bolt with a diameter of not less than 8mm, or other parts for grounding wire connection, such as a grounding plate with sufficient area and connection holes). The grounding point should have a flat metal surface and be marked with an obvious grounding symbol "一" next to it. The grounding parts should have a reliable anti-rust coating or be made of stainless steel. 5.2.11 Capacitor voltage divider
The capacitor voltage divider in the transformer should comply with the provisions of JB/T8169. 5.2.12 Protective gap of carrier coupling device If a protective gap is installed between the low-voltage terminal and the grounding terminal of the capacitor voltage divider of the transformer, its power frequency discharge voltage should not be greater than 2kV (root mean square value).
6 Test methods
6.1 Test conditions
The factory test and type test of the transformer shall be carried out under the following conditions, except for those specified in the relevant standards and the relevant clauses of this standard:
a) The ambient air temperature is +5~+35°C, and the temperature of the test piece shall not be significantly different from the ambient air temperature. After the test piece has been placed in a constant ambient air temperature for a suitable period of time without power, it is considered to be the same as the ambient air temperature. b) The power frequency voltage waveform used in the test shall comply with the provisions of GB/T16927.1, and the frequency is (0.91.1)fn. 6.2 Test of capacitor voltage divider
Except for the provisions of this standard, the test of capacitor voltage divider shall be carried out in accordance with JB/T8169. 6.3 Sealing test
The sealing test method of the electromagnetic unit shall be specified by the manufacturer. 6.4 Polarity test of winding
The polarity test of the electromagnetic unit winding is generally carried out by the DC method. 6.5 Withstand voltage test
Except for the following provisions, the rest shall be carried out in accordance with the relevant provisions of GB/T16927.1. 6.5.1 Withstand voltage test between primary terminals The test voltage is applied between the high voltage terminal and the grounding terminal (the low voltage terminal is connected to the grounding terminal). The short-time power frequency withstand voltage test (thousand-time test and wet test) is carried out on the capacitor voltage divider and the electromagnetic unit respectively. The test method for the electromagnetic unit is shown in 6.5.4.
The lightning impulse withstand voltage test is preferably carried out on the transformer as a whole, and the waveform of the test voltage is (1.2~5)/(40~~60)μs. Alternatively, it is carried out on the capacitor voltage divider and the electromagnetic unit respectively, and the test voltage of the electromagnetic unit is calculated according to formula (2). The switching impulse withstand voltage test (wet test) is preferably carried out on the transformer as a whole, and the waveform of the test voltage is 250/2500μS. Alternatively, it is carried out only on the capacitor voltage divider, and the electromagnetic unit is assessed by the above-mentioned short-time power frequency withstand voltage test. During the lightning impulse withstand voltage test and the switching impulse withstand voltage test, positive and negative impulses shall be applied 15 times each. If no more than 2 flashovers and no breakdown occur in 15 consecutive impulses, the transformer is considered to have passed the test. 6.5.2 Power frequency withstand voltage test of the low voltage terminal of the capacitor voltage divider to the ground 8
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