Some standard content:
GB17201-1997
This standard is equivalent to IEC44-3:1980 "Combined Transformer". The technical requirements and tests included in this standard, together with the technical requirements and tests included in GR1208+1997 "Current Transformer" and GB1207-1997 "Electric Transformer", are applicable to combined transformers. This standard directly refers to GB12081997 "Current Transformer" (eg VIEC185:1987 Current Transformer) and its No. 1 Amendment (1990), No. 2 Amendment (1905) and GB1207-1997 Voltage Transformer (eg VIEC186:1987 "Voltage Transformer" Amendment No. 1 (1990), No. 2 Amendment (1995)): while IEC:443:1980 "Combined Transformer" refers to the 1969 version of IEC185 Current Transformer and TFC186 Electric Transformer", after citing the new version, this standard is more in line with the current international standard level, and it also promotes the improvement of the technical level of my country's combined sensor products. Appendix A of this standard is a suggestive appendix. This standard is proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Standardization of Sensors. The main drafting units of this standard: Shenyang Transformer Research Institute, Jiangxi Mechanical Equipment Factory, Zhongshan Litai Machine Core Factory, Shunde Special Transformer Factory, Nanjing Electric Ceramics Factory, Shanghai Sensor Factory, Shenyang Transformer Co., Ltd., Wuhan High Voltage Research Institute. The main drafters of this standard: Huang Peinen, Tian Wenge, Zhang Aimin, He Jianguang, Hu Pei, He Ping, Xu Dean, Ye Guoban, Wei Zhaohui. This standard is interpreted by Shenyang Transformer Research Institute. This standard was first issued in December 1997. GB 17201—1997
IEC Foreword
This standard was prepared by IEC/TC 38 Instrument Transformers\Technical Committee. The first draft of this standard was discussed at the Nice Conference in 1976. As a result of this conference, Draft Document 38(CO)34 was produced and submitted to the National Committees for voting in August 1977 according to the six-month method. The following countries voted in favor of this standard: Australia, Austria, Belgium, Denmark, Egypt, Netherlands, France, Germany, Hungary, Israel, Italy, Japan, Poland, Romania, South Africa, Spain, Switzerland, Turkey, United Kingdom, Yugoslavia. Other IEC standards referenced in this standard are:
"Transformers Part 4 Partial Discharge Measurement"
EC 44-4:1980
IEC 185.1969
IEC 186:1969
IEC 270:1968
《Current Transformer》
Multiple Current Transformers》
Local Electrical Measurement
Due to the emergence of IEC185 and IEC186, the original IEC44 series of standards (established in 1931) are obsolete. When these two standards are republished, they will be numbered 1EC44-1 and 1EC44-2 respectively. Therefore, this standard can be considered as a sequel to these two standards. 1 Scope
National Standard of the People's Republic of China
Combined transformers
Comhined transformers
GB17201—1997
eqvIEC44-3:1980
This standard specifies the technical requirements, test methods and markings for newly manufactured combined transformers. The current transformers and voltage transformers (including capacitive voltage transformers) that constitute combined transformers shall also comply with the technical requirements and test methods in GB1208, GB1207 and GB4703.
Note: This standard does not include special requirements for three-phase combined transformers, but the relevant parts required in this standard are also applicable to three-phase combined transformers. 2 Referenced 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. GB1207-1997 Voltage transformer (eqIEC185, 1987) GB1208-1997 Current transformer (eqvIEC186: 1987) GB470384 Capacitor voltage transformer
3 Definitions
This standard adopts the following definitions.
Combined transformers A transformer consisting of a current transformer and a voltage transformer and installed in the same housing. 4 Error Limits
4.1 Overview
For combined transformers for measurement, the error limits shall comply with the technical requirements of 5.3 current transformers for measurement in GB1208-1997 and 5.2 voltage transformers for measurement in GB1207-1997 or 3.8 of GB4703-84. For combined transformers for protection, the error limits shall comply with 6.3 current transformers for protection in GB1208-1997 and 6.2 voltage transformers for protection in GB1207-1997 or 3.8 of GB4703-84. 4.2 Mutual Influence
4.2.1 When the current transformer operates within the range between 5% of the rated current and the rated continuous thermal current, and the voltage transformer operates within the specified load range and at the specified voltage, the voltage error and phase difference of the voltage transformer shall not exceed the limits specified by the corresponding accuracy level. When the load of the current transformer has no significant effect on the measurement result, its secondary winding can be short-circuited. 4.2.2 When the voltage transformer operates at a voltage value between 80% of the rated voltage and the rated voltage multiplied by the rated voltage factor, and the current transformer operates at any load value between 25% and 100% of the rated load, the current error and phase difference of the current transformer shall not exceed the limit specified by its corresponding accuracy level.
4.2.3 The nameplate of the combined transformer shall be marked with the induced voltage U generated by the rated short-time thermal current of the current transformer when the primary winding of the voltage transformer is short-circuited. State Administration of Technical Supervision Approved on December 30, 1997, and implemented on October 1, 1998
..comGB17201—1997
(root mean square value) on the voltage transformer. Value. This induced voltage is measured at the two winding outlet terminals when the voltage transformer load is 15VA or rated load. Note: The ratio of the induced voltage to the thermal current flowing through the current transformer at a fixed torque can be marked on the nameplate, expressed in mV/kA, to replace the value induced by the rated short-time thermal current (RMS). 5 Temperature rise limit
According to the provisions of 4.5 of GB1207-1997, the core voltage is added to the combined transformer, and the H core current transformer When the primary current of the transformer is equal to the rated continuous thermal current, the temperature rise of the combined transformer should not exceed the values specified in 4.2.6 of GB1208-1997 and 4.5 of GB1207-1997 respectively. At this time, the power factor of the current transformer load is 0.8 (after boiling) ~ 1, and the load value corresponds to its rated output, while the load of the voltage transformer is the rated load or the maximum rated load (when there are several rated loads), and the H power factor is between 8 (after boiling) ~ 1. The requirement that the temperature rise value of the voltage transformer is allowed to be 10K higher than the specified value under specified circumstances can also be applied to the current transformer in the combined transformer.
6 Type test
According to 4.4.2 of GB 1208-1997, 4.9.1 of GB1207-1997 or 5.3 of GB 4703-84, 6.1 Impulse withstand voltage test
When the combined inductor is subjected to the impulse test, the impulse voltage shall be applied to the short-circuited primary winding of the current transformer, which shall be connected to the secondary winding of the current transformer which is at high voltage during operation. The test shall be carried out in accordance with 4.5.3 of GB1208-1997 and 4.10.3 of GB1207-1997, respectively. 6.2 Temperature rise test
This test is for testing the combination.Whether the sensor meets the provisions of Chapter 5. When the temperature rise does not exceed 1K per hour, it is considered to have reached a stable value. The ambient temperature during the test is between (5 and 10)°C. Unless otherwise agreed by the manufacturer and the user, when there are several secondary windings, the test is carried out with each secondary winding connected to its corresponding rated load. During the test, the combined transformer should be applied to the combined transformer according to the operating state. The specified current and voltage values are applied to the combined transformer at the same time. For this purpose, the insulation between the primary winding of the transformer that produces a large current for the excitation of the current transformer and its secondary winding must be considered according to the full system voltage.
If such a transformer cannot be used, the combined transformer can be placed insulated from the ground. In this way, high voltage can be applied simultaneously to the base, the case, the primary winding terminal that is usually grounded during operation, and one terminal of each secondary winding. At this time, the "winding terminal" connected to the power grid line is grounded during operation. Transformers used to generate large currents do not need to be made into high-insulation structures. The results of these two methods are the same. The temperature rise of the system should be measured by the resistance method. For the winding of the current transformer with very low resistance, the thermocouple method can be used. For the temperature rise of other parts outside the winding, a thermometer or a thermocouple can be used to measure. 6.3 Determination of error
6.3.1 The determination of error shall be in accordance with 5.4.1 and 6.4.2 of GB 1208-1997, 5.4.1 and 6.5.1 of GB 1207-1997 or 4-5 of GB4703-84.
6. 3.2 In the combined transformer, the influence of the current transformer on the voltage transformer shall be tested in the following manner. 6.3.2.1 First, when the current transformer does not pass current, the voltage error and phase difference of the current transformer shall be measured at the rated load and 25% of the rated load according to the provisions of 5.4.1, 6.5.1 of GB1207-1997 or 4.5 of GB 4703-84. Then, the rated continuous thermal current is applied to the current transformer. The power supply circuit of the current transformer shall be arranged into a horizontal loop according to the height of the primary terminal of the current transformer (see Figure 1). Instructions for the use of loop conductors
1 The original IEC text stipulates that the ambient temperature during the test is between (11~30)℃, which is changed to 5~10)℃ according to my country's national conditions. GB 17201—1997
The distance α (see Table 1 or Table 21\) should correspond to the distance between the phase conductors in the power grid line. Unless otherwise agreed between the user and the manufacturer, the α value should generally be selected according to Table 2. The primary winding of the current transformer should be short-circuited with the shortest possible wire. This short-circuit wire should be located perpendicular to the primary terminal of the current transformer.
The voltage value generated by the current flowing through the voltage transformer can be measured on its secondary terminal with a milliohmmeter or an indicator. This voltage value U is a measure of the maximum change in voltage error. In order to prevent errors caused by external interference voltage, the recommended load of the voltage transformer is 15VA. For protective transformers, the voltage change is 4e, with 2% of the rated secondary voltage as the standard value; for measuring transformers, 80% of the rated secondary voltage can meet the requirements as the reference value, so the maximum possible change in voltage error is: +4ev—100U/0.8Us) % (expressed as a percentage of 80% of the rated secondary voltage value) + A5 = 100U/(0.02U)% (expressed as a percentage of 2% of the rated secondary voltage value) The maximum possible change in phase difference is:
-34.4() or
+Aiv-Aecrad
In the formula: UsN-rated secondary voltage.V;
U——the induced voltage generated by the rated continuous thermal current, V. If the absolute value of the voltage error change "Ae" and the potential difference change +△ are added to the absolute values of ev and [aevl] measured at rated load and 25% rated load and 80% rated voltage when the current is not passing, the result is: ±e+el+[aevl,li
They should not exceed the limit values of voltage transformer errors specified in 5.2 and 6.2 of GB1207-1997 or 3.8 of GB4703-84 (see Figure 4).
Even at other specified voltages, the voltage error caused by the influence of current should not exceed the limit. 6.3.2.2 To confirm that the requirements of 4.2.3 are met, the induced voltage value caused by the rated short-time thermal current marked on the nameplate can be calculated according to the voltage U measured at the rated continuous thermal current as described in 6-3.2.1. The induced voltage value generated by the rated short-time thermal current is: U. = Uv'p
Where: U is the induced voltage generated by the rated continuous thermal current, VIs—rated short-time thermal current, A!
Ir—rated continuous thermal current, A
Note: To improve the accuracy, the induced voltage should be measured at the maximum possible voltage value. 6.3.3 Confirm that the requirements of 4.2.2 are met. The influence of the voltage transformer in the combined sensor on the current transformer should be tested according to the following method:
First, when the voltage transformer is not magnetized, the current error and phase difference of the current transformer are determined according to 5.4.16.4.2 of GB1208-1997.
Then apply 120% of the rated voltage and the voltage value of the rated voltage multiplied by the rated voltage factor to the terminal of the current transformer directly connected to one terminal of the current transformer. At this time, the current transformer is not magnetized. The applied voltage generates a capacitance voltage in the current transformer, and can be measured by the voltage drop across the resistor R connected between the secondary terminals of the current transformer. Since the load of the secondary winding of the voltage transformer does not affect the result, its secondary winding can be exposed. Instructions:
1 Table 1 is the original provisions of 1FC: The values listed in Table 2 are given according to Chinese standards. 2TEC was originally at 100% and 120% of the rated medium voltage, but now it is changed to at the specified voltage, which is more stringent than IFC, GB 17201-1997
When the rated secondary current of the current transformer is 1A, the recommended R is 100; and when the rated secondary current is 5A, R is 5N. When the rated secondary current is 2A, R is 250. If the accuracy of R is ±10%, it can meet the requirements. First, measure the voltage drop U: when the S1 terminal of the current transformer secondary winding is grounded (see Figure 2), and then measure the voltage drop U when the S2 terminal of the current transformer secondary winding is grounded (see Figure 3). The larger value of the two measurements is used as the value for calculation. Note: According to the agreement between the manufacturer and the user, only the grounding of the terminal to be grounded during operation can meet the requirements. The passband is sufficient to determine the influence of this voltage at 5% of the rated current. Therefore, the current error change is:
±△6=100U./(0.05IsyR)% (expressed as a percentage of 5% of the rated current) The phase difference change is:
±;=34. 4() or
±0= crad
Where: Rn,
Isn—rated secondary current, A.
If the absolute values of the current error change ±A and the phase difference change § are added to the absolute values of and measured at the rated load and 25% rated load and 5% rated current when the voltage transformer is not excited, we can get: ±e,=le:|+[Ae:1 and
±8,-{01+{41
(see Figure 5)
They should not exceed the error limits of current transformers specified in 5.3 and 6.3 of GB1208-1997. Even at 5% to 120% of the rated current, or even at the rated expanded current value (if specified), the current error should not exceed its error limit. Position stomach
CVCT: Combination transformer,
CG, the transformer that generates current, its leakage magnetic field should not affect the combination transformer. If it is found that there is an impact at position A, it should be placed at position B: αi The distance between the loop conductors, see Table 1 or Table 2. Figure 1 Geometrical layout of the line
Equipment maximum voltage, kV
Full insulation
Reduced insulation
GB 1720′—1997
Equipment maximum voltage, k
Note: The values listed in this competition are not applicable to complete sets of distribution equipment produced by the manufacturer.
Error limit
Aev: The error change caused by the current. According to the angle Aev between the current and voltage vectors, the whole point is located on the circle with the voltage transformer error when there is no current as the center.
A. The error of the voltage transformer when the output is 15VA. B, the error of the voltage transformer when the output is VA. Figure 40. Error diagram of level 2 voltage transformer
.·10r
GB 172011997
Error limit
5: Error change caused by external follower self-rejection. The end point of the angle between the voltage and current is located on the circle with the current transformer error when there is no external voltage influence as the center.
4: Error of the current transformer when the output is 15VA. 3: Error of the good current transformer when the output is 3.75 VA. Figure 5 (.2 Class current transformer standard: error at 5% rated current Figure 7 Routine test
According to 4.4.3 of GB 1208-1997, 4.9.2 of GB 1207-1997 or 5.2 of GB 470384. 7.1 Inspection of terminal markings and nameplate ratings Inspection of terminal markings and nameplate ratings shall be in accordance with 4.9, 5.5, 6.5 of GR1208-1997 and 4.11, 4.12, 5.5, 6.6 of GB1207-1997 or 5.2 of GB 6 of 4703--84. 7.21. Power frequency withstand voltage test
7.2.1 Primary winding
If there is an ungrounded voltage transformer in the combined transformer, the power frequency withstand voltage test of the voltage transformer primary winding and the current transformer primary winding shall be carried out at the same time. The test requirements shall be in accordance with GB1207-1997; the inductive withstand voltage test of the voltage transformer secondary winding shall be carried out in accordance with 4.10.10 of GB1207-1997.
If there is a grounded voltage transformer in the combined transformer, the inductive withstand voltage test of the voltage transformer primary winding and the power frequency withstand voltage test of the current transformer secondary winding shall be carried out at the same time. The test requirements shall be in accordance with CB1207-1997; the power frequency withstand voltage test of the grounding terminal of the voltage transformer primary winding shall be carried out in accordance with 4.6 of GB 1207-1997. 2.2. 7.2.2 Secondary winding
Current transformer The power frequency withstand voltage test of the secondary winding shall be in accordance with 4.6.3 of GB1208-1997, and the overvoltage test of the current transformer shall be in accordance with 4.6.4 of GB1208-1997. The power frequency withstand voltage test of the secondary winding of the voltage transformer shall be in accordance with 4.10.11 of GB1207-1997 and 4.1.2 of GB 1703-84. Instructions for use:
1: There are some differences between my country's C[311.1 standard and the corresponding IEC standard, so this article is modified. 7.3 Partial discharge measurement bZxz.net
CB 17201-1997
If partial discharge measurements are required, they shall be carried out in accordance with 4.6.2 of GB1208-1997 and 4.10.10 of GB1207-1997 or 3.12 of GB4703-84.
7.4 Error determination
7.4.1 The error determination of current transformers shall be carried out in accordance with 5.4.2 and 6.4.3 of GB1208-1997. The error determination of voltage transformers shall be carried out in accordance with 5.4.2 and 6.5.2 of GB 1207-1997 and 4.5 of GB 1703-84. 7.4.2 The error variation shall be taken into account, which shall be determined in accordance with 6-3.2 and 6.3.3 during the type test. 8 Special tests\
According to 4-4, 4-6 of GB 1208-1997 and 4.9.3 of GB 1207-1997. 9 Marking
9.1 Sheath marking
The terminal marking method of the current transformer and voltage transformer in the combined transformer is the same as that of the single transformer. 9.2 Nameplate marking
The nameplate shall include the provisions of 4.9.2, 5.5 and 6.5 of GB1208-1997 for current transformers and 4.11.5.5.6.6 of GB1207-1997 for voltage transformers or 6 of GB4703-84. In addition, for voltage transformers, the induced voltage value of the current transformer under the rated short-time thermal current of the current transformer (according to 4.2.3) shall also be marked (for example, U.-47 mV), or its mV/kA value (according to the note of 4.2+3) shall be marked. Instructions for use:
17[FC14-1:1980 does not have this requirement. This requirement is added according to the provisions of GB1207 and G[31208. GB17201-1997
Appendix A
(Suggested Appendix)
Interaction between current transformer and voltage transformer A1 Influence of magnetic field of current-carrying conductor on voltage transformer error The magnetic field generated by current-carrying conductor near voltage transformer can affect its error. This influence is greatest when the conductor is arranged horizontally at an angle of 90° to the core axis and the magnetic flux around the conductor passes through an open circuit winding (see Figure A1, in a sensor with a rated voltage of 10kV). When the conductor is parallel to the core axis, the influence is actually non-existent. This is important for combined transformers. When designing, care should be taken to place the voltage transformer in the correct position, even if its core axis is parallel to the direction of the current-carrying conductor passing through the top of the five sensors. It is particularly important to understand the influence of the magnetic field generated by the current-carrying conductor on the error of the voltage sensor when using directional relay protection. The accuracy of the voltage transformer must be guaranteed, and special attention should be paid to the phase difference of its secondary voltage to the primary voltage, because the induced voltage phasor generated by the current has a 90° phase shift with respect to the primary voltage. If the secondary voltage is 0.5V and its induced voltage is 50mV during the fault, the error of the secondary voltage will be greater than 10%. If the current-carrying conductor in the power grid is located near the voltage transformer, the current-carrying conductor will not only affect the combined transformer, but also any independent voltage transformer with a system voltage of 0.6kV and above. Therefore, the above requirements still apply to independent voltage transformers. A2 Effect of applied voltage on the error of the current transformer To measure the error of the current transformer, generally only a low voltage that can produce a suitable output current is required. If a high voltage is applied to the primary winding of the sensor, the error will vary somewhat due to the capacitive current flowing from the primary winding to the secondary winding (when the secondary winding is unshielded), part of which flows through the instrument connected to the secondary winding and part of which flows directly to the ground of the secondary winding. Even if the secondary winding is shielded, the capacitive current flowing through the primary winding will also cause an induced current in the secondary winding. Especially at 5% of the rated current, this error may be greater than the error limit. If the error of the current transformer is measured while applying a high voltage, the reference (standard) current transformer used for this test and the transformer generating the high current should be insulated according to the high voltage. For the purpose of measurement, they can be separate structures. But it is more practical for the two units to have a common high current winding (i.e., the reference current transformer). The unit itself should be insulated from the high voltage. At this time, care should be taken to shield the core and secondary winding of the reference current transformer and the core and primary winding of the high current transformer. The high current winding can also be shielded by a wire connected to the terminals of the winding. This wire is connected to the transformer side of the high current winding so that the high voltage to ground capacitance is connected to the high voltage transformer and flows into the ground without passing through the high current winding. The methods for measuring the influence of current-carrying wires on voltage transformers and the influence of applied voltage on current transformers described in 6.3.2 and 6.3.3 are both indirect methods. It may be easier to obtain the same measurement results than the direct method. For the indirect method, it is not necessary to equip the above transformer with high voltage insulation. GB17201-1997
Figure A1 The influence of current-carrying wires and magnetic fields on voltage transformers 1600The voltage withstand test is carried out at the same time, and the test requirements are in accordance with CB1207-1997; the power frequency withstand voltage test of the grounding terminal of the voltage transformer primary winding is carried out in accordance with 4.6.2.2 of GB 1207-1997. 7.2.2 Secondary winding
The power frequency withstand voltage test of the secondary winding of the current transformer is carried out in accordance with 4.6.3 of GB1208-1997, and the overvoltage test of the current transformer is carried out in accordance with 4.6.4 of GB1208-1997. The power frequency withstand voltage test of the secondary winding of the voltage transformer is carried out in accordance with 4.10.11 of GB1207-1997 and 4.1.2 of GB 1703-84. Instructions for adoption:
1: There are some differences between my country's C[311.1 standard and the corresponding IEC standard, so this article is modified. 7.3 Partial discharge measurement
CB 17201—1997
If partial discharge measurement is required, it shall be in accordance with 4.6.2 of GB1208—1997 and 4.10.10 of GB1207—1997 or 3.12 of GB4703—84.
7.4 Error determination
7.4.1 The error determination of current transformers shall be in accordance with 5.4.2 and 6.4.3 of GB1208-1997. The error determination of voltage transformers shall be in accordance with 5.4.2 and 6.5.2 of GB 1207-1997 and 4.5 of GB 1703—84. 7.4.2 The error variation shall be taken into account, which is determined in the type test in accordance with 6-3.2 and 6.3.3. 8 Special tests\
According to the provisions of 4-4, 4 of GB 1208-1997 and 4.9.3 of GB 1207--1997. 9 Marking
9.1 Sheath marking
The terminal marking method of the current transformer and voltage transformer in the combined transformer is the same as that of the single transformer. 9.2 Nameplate marking
The nameplate should include the provisions of 4.9.2, 5.5 and 6.5 of GB1208-1997 for current transformers and 4.11.5.5.6.6 of GB1207-1997 for voltage transformers or the provisions of 6 of GB4703-84. In addition, for voltage transformers, the induced voltage value of the current transformer under the rated short-time thermal current of the current transformer (according to 4.2.3) should also be marked (for example, U.-47 mV), or its mV/kA value should be marked (according to the note of 4.2+3). Adoption instructions:
17[FC14-1:1980 does not have this requirement, and this requirement is added according to the provisions of GB1207 and GB31208. GB17201-1997
Appendix A
(Suggested Appendix)
Interaction between current transformer and voltage transformer A1 Influence of magnetic field of current-carrying conductor on voltage transformer error The magnetic field generated by the current-carrying conductor near the voltage transformer can affect its error. This effect is greatest when the conductor is arranged horizontally at an angle of 90° to the core axis and the magnetic flux around the conductor passes through an open winding (see Figure A1, in a sensor with a rated voltage of 10kV). When the conductor is parallel to the core axis, the effect is virtually non-existent. This is important for combined transformers. Care should be taken in the design to place the voltage transformer in the correct position, even if its core axis is parallel to the direction of the current-carrying conductor passing through the top of the sensor. It is particularly important to understand the effect of the magnetic field generated by the current-carrying conductor on the voltage sensor error when using directional relay protection. The accuracy of the voltage transformer must be guaranteed, especially the phase difference of its secondary voltage to the primary voltage, because the induced voltage phasor generated by the current has a 90° phase shift with respect to the primary voltage. If the secondary voltage is 0.5V at the time of the fault and its induced voltage is 50mV, then the secondary voltage will have an error of more than 10%. If the current-carrying conductor in the network is located near the voltage transformer, the current-carrying conductor will not only affect the combined transformer, but also any independent voltage transformer with a system maximum voltage of 0.6kV and above. Therefore, the above requirements still apply to independent voltage transformers. A2 Effect of applied voltage on the error of current transformer To measure the error of current transformer, generally only a low voltage that can produce a suitable output current is required. If a high voltage value is applied to the primary winding of the sensor, the error will change slightly because the capacitive current caused by this voltage flows from the primary winding to the secondary winding (when the secondary winding is not shielded), part of which flows through the instrument connected to the secondary winding and the other part flows directly to the ground of the secondary winding. Even if the secondary winding is shielded, the capacitive current flowing through the primary winding will also cause an induced current in the secondary winding. Especially at 5% of the rated current, this error may be greater than the error limit. If the error of the current transformer is measured while applying high voltage, the reference (standard) current transformer used for this test and the transformer producing the high current should be insulated for the high voltage. For the purpose of the test, they can be separate structures. However, it is more practical for the two units to have a common high current winding (which belongs to the reference current transformer). This winding should itself be insulated from the high voltage. In this case, care should be taken to shield the core and secondary winding of the reference current transformer and the core and primary winding of the high current transformer. The high current winding can also be shielded by a shield connected to the terminals of the winding, which is connected to the high voltage transformer side of the reference current winding so that the high voltage to ground capacitance is connected to the high voltage transformer and does not flow through the high current winding. The methods described in 6.3.2 and 6.3.3 for measuring the effect of current-carrying conductors on voltage transformers and the effect of applied voltage on current transformers are both indirect methods. It may be easier to obtain the same measurement results than the direct method. For the indirect method, it is not necessary to equip the above transformer with high voltage insulation GB17201—1997
Figure A1 Effect of current-carrying conductor and magnetic field on voltage transformer 1600The voltage withstand test is carried out at the same time, and the test requirements are in accordance with CB1207-1997; the power frequency withstand voltage test of the grounding terminal of the voltage transformer primary winding is carried out in accordance with 4.6.2.2 of GB 1207-1997. 7.2.2 Secondary winding
The power frequency withstand voltage test of the secondary winding of the current transformer is carried out in accordance with 4.6.3 of GB1208-1997, and the overvoltage test of the current transformer is carried out in accordance with 4.6.4 of GB1208-1997. The power frequency withstand voltage test of the secondary winding of the voltage transformer is carried out in accordance with 4.10.11 of GB1207-1997 and 4.1.2 of GB 1703-84. Instructions for adoption:
1: There are some differences between my country's C[311.1 standard and the corresponding IEC standard, so this article is modified. 7.3 Partial discharge measurement
CB 17201—1997
If partial discharge measurement is required, it shall be in accordance with 4.6.2 of GB1208—1997 and 4.10.10 of GB1207—1997 or 3.12 of GB4703—84.
7.4 Error determination
7.4.1 The error determination of current transformers shall be in accordance with 5.4.2 and 6.4.3 of GB1208-1997. The error determination of voltage transformers shall be in accordance with 5.4.2 and 6.5.2 of GB 1207-1997 and 4.5 of GB 1703—84. 7.4.2 The error variation shall be taken into account, which is determined in the type test in accordance with 6-3.2 and 6.3.3. 8 Special tests\
According to the provisions of 4-4, 4 of GB 1208-1997 and 4.9.3 of GB 1207--1997. 9 Marking
9.1 Sheath marking
The terminal marking method of the current transformer and voltage transformer in the combined transformer is the same as that of the single transformer. 9.2 Nameplate marking
The nameplate should include the provisions of 4.9.2, 5.5 and 6.5 of GB1208-1997 for current transformers and 4.11.5.5.6.6 of GB1207-1997 for voltage transformers or the provisions of 6 of GB4703-84. In addition, for voltage transformers, the induced voltage value of the current transformer under the rated short-time thermal current of the current transformer (according to 4.2.3) should also be marked (for example, U.-47 mV), or its mV/kA value should be marked (according to the note of 4.2+3). Adoption instructions:
17[FC14-1:1980 does not have this requirement, and this requirement is added according to the provisions of GB1207 and GB31208. GB17201-1997
Appendix A
(Suggestive Appendix)
Interaction between current transformer and voltage transformer A1 Influence of magnetic field of current-carrying conductor on voltage transformer error The magnetic field generated by the current-carrying conductor near the voltage transformer can affect its error. This effect is greatest when the conductor is arranged horizontally at an angle of 90° to the core axis and the magnetic flux around the conductor passes through an open winding (see Figure A1, in a sensor with a rated voltage of 10kV). When the conductor is parallel to the core axis, the effect is virtually non-existent. This is important for combined transformers. Care should be taken in the design to place the voltage transformer in the correct position, even if its core axis is parallel to the direction of the current-carrying conductor passing through the top of the sensor. It is particularly important to understand the effect of the magnetic field generated by the current-carrying conductor on the voltage sensor error when using directional relay protection. The accuracy of the voltage transformer must be guaranteed, especially the phase difference of its secondary voltage to the primary voltage, because the induced voltage phasor generated by the current has a 90° phase shift with respect to the primary voltage. If the secondary voltage is 0.5V at the time of the fault and its induced voltage is 50mV, then the secondary voltage will have an error of more than 10%. If the current-carrying conductor in the network is located near the voltage transformer, the current-carrying conductor will not only affect the combined transformer, but also any independent voltage transformer with a system maximum voltage of 0.6kV and above. Therefore, the above requirements still apply to independent voltage transformers. A2 Effect of applied voltage on the error of current transformer To measure the error of current transformer, generally only a low voltage that can produce a suitable output current is required. If a high voltage value is applied to the primary winding of the sensor, the error will change slightly because the capacitive current caused by this voltage flows from the primary winding to the secondary winding (when the secondary winding is not shielded), part of which flows through the instrument connected to the secondary winding and the other part flows directly to the ground of the secondary winding. Even if the secondary winding is shielded, the capacitive current flowing through the primary winding will also cause an induced current in the secondary winding. Especially at 5% of the rated current, this error may be greater than the error limit. If the error of the current transformer is measured while applying high voltage, the reference (standard) current transformer used for this test and the transformer producing the high current should be insulated for the high voltage. For the purpose of the test, they can be separate structures. However, it is more practical for the two units to have a common high current winding (which belongs to the reference current transformer). This winding should itself be insulated from the high voltage. In this case, care should be taken to shield the core and secondary winding of the reference current transformer and the core and primary winding of the high current transformer. The high current winding can also be shielded by a shield connected to the terminals of the winding, which is connected to the high voltage transformer side of the reference current winding so that the high voltage to ground capacitance is connected to the high voltage transformer and does not flow through the high current winding. The methods described in 6.3.2 and 6.3.3 for measuring the effect of current-carrying conductors on voltage transformers and the effect of applied voltage on current transformers are both indirect methods. It may be easier to obtain the same measurement results than the direct method. For the indirect method, it is not necessary to equip the above transformer with high voltage insulation GB17201—1997
Figure A1 Effect of current-carrying conductor and magnetic field on voltage transformer 1600This effect is greatest when the conductor is parallel to the core axis. This effect is virtually non-existent when the conductor is parallel to the core axis. This is important for combined transformers. Care should be taken during design to place the voltage transformer in the correct position, i.e., to place the core axis parallel to the current-carrying conductor passing through the top of the transformer. It is particularly important to understand the effect of the magnetic field generated by the current-carrying conductor on the voltage sensor error when using directional relay protection. The accuracy of the voltage transformer must be guaranteed, with particular attention paid to the phase difference of its secondary voltage to the primary voltage, because the induced voltage phasor generated by the current has a 90° phase shift with respect to the primary voltage. If the secondary voltage is 0.5V at the time of the fault and its induced voltage is 50mV, the resulting error of the secondary voltage will be greater than 10%. If the current-carrying conductor in the network is located near the voltage transformer, the current-carrying conductor will have an effect not only on the combined transformer, but also on any independent voltage transformer with a system maximum voltage of 0.6kV and above. Therefore, the above requirements still apply to independent voltage sensors. A2 Effect of applied voltage on current transformer error To measure the error of a current transformer, it is generally sufficient to have a low current that produces a suitable output current. If a high voltage is applied to one winding of the transformer, the error will vary somewhat because the capacitive current caused by this voltage flows from the primary winding to the secondary winding (when the secondary winding is unshielded), part of which flows through the instrument connected to the secondary winding and the other part flows directly to the ground of the secondary winding. Even if the secondary winding is shielded, the capacitive current flowing through the primary winding will also cause an induced current in the secondary winding. Especially at 5% of the rated current, this error may be greater than the error limit. If the error of the current transformer is measured while applying a high voltage, the reference (standard) current transformer used for this test and the transformer producing the high current should be insulated according to the high voltage. For the purpose of the test, they can be separate structures. But it is more practical to have a common high current winding between the two sets (i.e., the reference current transformer). The transformer itself should be insulated from the high voltage. At this time, attention should be paid to shielding the reference current transformer core and secondary winding as well as the high current transformer core and primary winding. The high current winding can also be shielded by a shield connected to the terminals of the winding. This shield is connected to the high voltage transformer side of the reference current winding so that the high voltage to ground capacitance is connected to the high voltage transformer and flows into the ground without passing through the high current winding. The methods for measuring the influence of current-carrying conductors on voltage transformers and the influence of applied voltage on current transformers introduced in 6.3.2 and 6.3.3 are both indirect methods. It may be easier to obtain the same measurement results than the direct method. For the indirect method, it is not necessary for the above transformer to be equipped with high voltage insulation GB17201—1997
Figure A1 Influence of current-carrying conductors and magnetic fields on voltage transformers 1600This effect is greatest when the conductor is parallel to the core axis. This effect is virtually non-existent when the conductor is parallel to the core axis. This is important for combined transformers. Care should be taken during design to place the voltage transformer in the correct position, i.e., to place the core axis parallel to the current-carrying conductor passing through the top of the transformer. It is particularly important to understand the effect of the magnetic field generated by the current-carrying conductor on the voltage sensor error when using directional relay protection. The accuracy of the voltage transformer must be guaranteed, with particular attention paid to the phase difference of its secondary voltage to the primary voltage, because the induced voltage phasor generated by the current has a 90° phase shift with respect to the primary voltage. If the secondary voltage is 0.5V at the time of the fault and its induced voltage is 50mV, the resulting error of the secondary voltage will be greater than 10%. If the current-carrying conductor in the network is located near the voltage transformer, the current-carrying conductor will have an effect not only on the combined transformer, but also on any independent voltage transformer with a system maximum voltage of 0.6kV and above. Therefore, the above requirements still apply to independent voltage sensors. A2 Effect of applied voltage on current transformer error To measure the error of a current transformer, it is generally sufficient to have a low current that produces a suitable output current. If a high voltage is applied to one winding of the transformer, the error will vary somewhat because the capacitive current caused by this voltage flows from the primary winding to the secondary winding (when the secondary winding is unshielded), part of which flows through the instrument connected to the secondary winding and the other part flows directly to the ground of the secondary winding. Even if the secondary winding is shielded, the capacitive current flowing through the primary winding will also cause an induced current in the secondary winding. Especially at 5% of the rated current, this error may be greater than the error limit. If the error of the current transformer is measured while applying a high voltage, the reference (standard) current transformer used for this test and the transformer producing the high current should be insulated according to the high voltage. For the purpose of the test, they can be separate structures. But it is more practical to have a common high current winding between the two sets (i.e., the reference current transformer). The transformer itself should be insulated from the high voltage. At this time, attention should be paid to shielding the reference current transformer core and secondary winding as well as the high current transformer core and primary winding. The high current winding can also be shielded by a shield connected to the terminals of the winding. This shield is connected to the high voltage transformer side of the reference current winding so that the high voltage to ground capacitance is connected to the high voltage transformer and flows into the ground without passing through the high current winding. The methods for measuring the influence of current-carrying conductors on voltage transformers and the influence of applied voltage on current transformers introduced in 6.3.2 and 6.3.3 are both indirect methods. It may be easier to obtain the same measurement results than the direct method. For the indirect method, it is not necessary for the above transformer to be equipped with high voltage insulation GB17201—1997
Figure A1 Influence of current-carrying conductors and magnetic fields on voltage transformers 1600
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