Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T 501-1991
Test Guidelines for Power Transformers
Published on 1991-06-28
Implemented on 1992-07-01 by the Ministry of Machinery and Electronics Industry of the People's Republic of China
Mechanical Industry Standard of the People's Republic of China
Test Guidelines for Power Transformers
Subject Content and Scope of Application
JB/T 501-1991
Replaces JB501-64
This standard specifies the methods and test procedures for factory tests, type tests, and special tests of oil-immersed and dry-type power transformers. This standard is applicable to the testing of oil-immersed and dry-type power transformers. Special transformers can refer to this standard. ] |tt||GB7600||tt| |GB7601
GB10230
ZBK41001
SY2654
Main special features
Rated voltage
I, rated current
S, rated capacity
K—-voltage ratio
R—resistance
t—temperature
Rxs——phase resistance
Rn——line resistance
Insulation coordination of high-voltage power transmission and transformation equipment
Determination of dielectric strength of insulating oil
Power transformer
Dry-type power transformer
High voltage test technology
Technical performance parameters and requirements of three-phase oil-immersed power transformersGuidelines for judgment of analysis of dissolved gases in transformer oilDetermination of sound level of transformers and reactors
Brow discharge measurement
Guidelines for lightning impulse and switching impulse tests on transformers and reactorsDetermination of moisture content in transformer oil during operation (coulometric method)Determination of moisture content in transformer oil during operation (gas chromatography)On-load tap-changer
Technical requirements for testing of used transformer oil
Determination of dielectric loss tangent of electrical oil V
K.Air density correction factor
Ka——air density
f——rated frequency
P. No-load loss
No-load current
Approved by the Ministry of Machinery and Electronics Industry on June 28, 1991Hz
Implemented on July 1, 1992
P.-~Load loss corrected to reference temperatureeImpedance voltage corrected to reference temperature
Z.-Short-circuit impedance
P,--Resistive loss
9,--Average temperature
A8Temperature rise
Z.-Zero sequence impedance
Z.--System impedance
Test procedure
JB/T 5011991
Test items not specified in this procedure shall be factory tested. The order of 4.3 to 4.7 can be interchanged, and the factory test and type test items of 4.8 to 4.26 shall be carried out in sequence. However, 4.10 to 4.14 shall be in accordance with the provisions of GB7449. 4.1
Mechanical strength test of oil tank (type test)4.2 Sealing test of oil tank
4.3 Insulation property test
4.3.1 Insulation resistance and absorption ratio measurement (all products of 35kV4000kV·A and above and 63kV and above should provide insulation resistance absorption ratio, other small and medium-sized transformers only provide resistance value)2 Dielectric loss rate measurement (all products of 35kV8000kV·A and above and 63kV and above)4.3.2
Transformer oil test
Transformer oil dielectric loss rate measurement panel
Transformer Oil gas content measuring panel
Transformer oil water content panel measurement
Transformer oil breakdown voltage measurement
Transformer oil gas chromatography measurement
Voltage ratio measurement
Voltage loss relationship correction
Winding resistance measurement
No-load loss and no-load current measurement (all products of 330kV and above) Partial discharge measurement (all products of 330kV and above) 4.10
Line end lightning full-wave impulse test (type test) Note:
Products with voltage of 220kV and capacity of 120MVA and above are factory tests. 4.11
Line rock lightning wave impulse test (type test) Neutral point full wave impulse test (type test) Neutral point non-lead lightning full wave impulse test (special test) Operation impulse test (all products of 330kV and above shall comply with the provisions of GB1094.3 Method 2) External withstand voltage test
No-load loss and no-load current measurement (all products of 35kV level 8000kV·A and above and $3kV and above) Induction withstand voltage test
Note: For products of 330kV and above, if there is no special requirement in the contract, it can comply with the provisions of GB1094.3 Method 1 or Method 2. 4.18
Partial discharge test panel (all products of 220kV and above) Note: It is a special test for dry-type transformers. 4.19
No-load loss and no-load current measurement
No-load current harmonic test (special test)4.21
Impedance voltage and load loss measurement
JB/T501-1991
Zero-sequence impedance measurement of three-phase transformer (special test)Operation test of on-load tap changer
Note: The operation test of on-load tap changer can be interspersed in the test. 4.24Temperature rise test (type test)
5Sound level measurement (special test)
Power measurement of fan motor and oil pump (special test)Short circuit test (special test)
Part I Factory Test
5Oil tank sealing test
The oil tank sealing test should be carried out on the assembled product. The oil storage cabinet, oil still, radiator or cooler with removable oil storage cabinet can be carried out separately. The test adopts one of the following methods: a. static oil column method, b. static air pressure method. 5.1 When the static oil column method is used for testing, a vertical hanging tank is added to the transformer cover or oil storage tank or the oil level pressure of the oil tank is used. The oil level height of the hanging chain or oil storage tank should make the pressure and duration of the oil tank meet the requirements of GB6451.1~6451.5. 5.2 When the static air pressure method is used for testing, a pressure gauge is connected to the transformer cover or oil storage tank. A valve should be installed outside the air vent plug of the storage tank. Dry air is input through the valve to apply static air pressure to the oil tank. The applied pressure and duration should meet the requirements of GB6451.1~6451.5. 5.3 Before releasing the sealing test, all welds and seals of the oil tank should be fully and carefully checked. There should be no oil seepage or leakage. When the static air pressure method is used to release the pressure, the residual pressure shall not be lower than the provisions of the relevant technical conditions. 5.4 For test products without oil cabinets or fully sealed types, the sealing test shall be carried out at the normal oil level. 5.5 For products transported by nitrogen filling, a secondary sealing test shall be carried out by filling with nitrogen under the transportation state. 5.6 When using the static oil column method or the static air pressure method, the pressure and duration of each part of the oil tank shall comply with the provisions of GB6451.1~6451.E. If there is no oil leakage in the product, the test is qualified.
6 Insulation property measurement
Insulation property measurement is to assess the insulation performance of the test product and is an important reference for high-voltage testing and operation. The following test items should be included:
, insulation resistance and absorption ratio measurement,
b, dielectric loss rate measurement.
The measurement positions of insulation resistance, absorption ratio and dielectric loss rate shall be carried out in accordance with the provisions of Table 1. 6.1 Insulation resistance and absorption ratio
6.1.1 The insulation resistance and absorption ratio (R.60/R_15, i.e. the ratio of insulation resistance 6CS to 15S) of all test pieces of 35kV level 4000kV.A and above and 5skV level and above shall be measured. A 5000V high resistance meter with an indication limit of not less than 100000MQ shall be used for measurement. The insulation resistance 60S value of all test pieces of 35kV level 3i5kV.A and below and 1CkV shall be measured with a 25CoV high resistance meter with an indication limit of not less than 1000GMQ. The accuracy is higher than ±1.5%. 6.1.2 When measuring insulation resistance. First adjust the megger to a horizontal level, and without connecting the test piece, turn on the power of the megger. 3
Sequence number
Measured coil
(off-voltage and low voltage)
Two-wire transformer
JB/T501-1991
Grounding part
Casing and high voltage
Casing and low voltage
(Casing)
Measured coil| |tt||(High and medium voltage)
Three-coil transformer
Grounding part
Casing, high and medium voltage
Casing, high and low voltage
Casing, medium and low voltage
(Casing and low voltage)
(High, medium and low voltage)
Note: Items 4 and 5 in frequency sequence in Table 1 are only for transformers of 16000kV·A and above. The instrument indication should be adjusted so that when the test connection cable is connected, the high resistance meter indication should have no obvious difference. 6.1.3 When using the high resistance meter, the three terminals of the high resistance meter must be grounded, the L terminal connected to the live wire, and the G terminal shielded. (External Yao)
6.1.4 When measuring, wait until the high resistance meter is at the rated voltage before connecting the line, and start timing at the same time. The handle speed of the manual high resistance meter should be evenly hooked and maintained at about 120 revolutions per minute.
6.1.5After each test, the live wire should be disconnected first to avoid the measured winding discharging to the high resistance meter after power failure and impacting the instrument in the opposite direction. 6.1.6Measure according to the test position in Table 1. When one position is tested, the measured winding should be discharged first, and then connected to another test position. The winding should be fully discharged before testing to eliminate the influence of residual charge on the measurement scene. 6.1.7When the air humidity is high and the leakage of the outer insulation surface is serious, the outer insulation surface should be shielded during measurement. 6.1.8During the test, the winding temperature should be between 10 and 40℃, and the resistance conversion at different temperatures should be in accordance with the relevant provisions of GB6451.1 to 6451.5.
6.2Measurement of dielectric loss rate
6.2.1The frequency of the test power supply should be the rated frequency, and its deviation should not exceed 5%. The test instrument adopts the "Xilin bridge" and the measurement is carried out by the reverse connection method.
6.2.2 The voltage applied shall be in accordance with the following provisions:
a. For test pieces with a rated voltage of 6kV and below, take the rated voltage, b. For test pieces with a rated voltage of 10-35kV, take 10kV, c. For test pieces with a rated voltage of 63kV and above. Take 10kV or more than 10kV, but not more than s0% of the lower voltage at the winding line end. 6.2.3 When there is doubt about the insulation performance of the test piece, its dielectric loss rate can be measured at different voltages. For well-insulated test pieces, the dielectric loss rate should remain unchanged or increase slightly with the increase of voltage. 6.2.4 At 10~40℃, the test results of the dielectric loss rate should not exceed the following provisions: a. The windings of 35kV and below should not be greater than 2% at 20℃; b. The windings of 63kV and above should not be greater than 1.5% at 20℃. When the winding temperature is different from 20℃, the conversion method shall be carried out according to the methods of GB6451.2~6451.5. 7. Transformer oil exposure test
Transformer oil breakdown test, the determination method shall be carried out according to G3507. For test regulations and qualified judgment, see ZBK41001.7.1
7.2 Transformer oil dielectric loss rate measurement, the determination method shall be carried out according to SY-2654. For test regulations and qualified judgment, see ZBK41001.7.3 Transformer oil water content test, the determination method shall be carried out according to the provisions of GB7600 or GB7601. For test regulations and qualified judgment, see ZBK41001.
JB/T501-1991
7.4 Transformer oil gas content test, the determination method shall be carried out according to the provisions of GB7252. For test regulations and qualified judgment, see ZBK410 (1. 7.5 The method of analysis of dissolved gas in transformer oil and the qualified judgment shall be in accordance with the provisions of GB7252 and the corresponding technical conditions. 8 Voltage ratio measurement || tt || The voltage ratio test is to verify whether the transformer can achieve the expected voltage conversion effect. The voltage ratio test after insulation assembly is to check whether the prime number and winding direction of the winding are correct; the voltage ratio test after lead assembly is to check whether the connection group number of the tap changer and the winding is correct; the voltage ratio test after general assembly is to check whether the internal position of the transformer tap changer is consistent with the external indication position and whether the line end mark is correct. 8.1 For windings with parallel branches, if a huge error can be obviously found in the voltage ratio test, the voltage ratio measurement should be carried out on each branch separately, otherwise, the potential difference test should be carried out to ensure that the parallel branches are connected. The number of turns is equal. Only under this premise can the voltage ratio measurement be carried out. The potential difference test method and precautions are as follows: 8.1.1 Supply an excitation voltage to the non-test winding, and its size should make the voltage per turn 1V. 8.1.2 Connect one end of the parallel branch and measure the potential difference of each end with the same name. The potential difference should be equal to zero. In order to avoid the potential difference being zero due to poor contact in the circuit, it is allowed to add a voltage in the measurement to make the potential difference 1V. The positive winding and the reverse winding should be temporarily connected in series in the circuit respectively, and the potential difference should be approximately equal to 1V.
8.1.3 In order to avoid the phenomenon that the potential difference decreases with the increase in the number of series turns, the voltmeter for measuring the potential difference should try to use a voltmeter with high internal resistance. 8.1.4 During the potential difference test, although the voltage of the test winding is only one volt, its potential is often very high. If there is a series line segment in the parallel branch, it can be used in the test. Open it and measure the potential difference of several parallel branches respectively to reduce the potential of the test winding. 8.1.5 One end of the measuring instrument should be reliably grounded, and the range of the instrument should be set to the maximum position at the beginning. After the power is turned on and the indication is positive, the range should be gradually reduced to avoid damaging the instrument.
8.2 The accuracy and sensitivity of the instrument used in the voltage ratio test should not be less than 0.2%. It is recommended to use a voltage ratio bridge (accuracy of 0.1%), and its principle wiring diagram is shown in Figure 1.
Amplifier
Principle diagram of voltage ratio bridge
K1 Error polarity conversion switch
K—Range switch
8.3 The ratio calculated in the voltage ratio test should be calculated according to the brand voltage of each tap. When the voltage percentage or the corresponding number of turns is no different from the brand voltage, the ratio can be calculated according to the voltage percentage or number of turns. . 8.4 The test should be carried out on each tap separately. For on-load tap-changing transformers with forward and reverse excitation, when the conversion selector is connected in the forward direction, if the voltage ratio measurement is carried out in all tap selector positions, when it is connected in the reverse direction, it is allowed to test only 1 to 2 taps. 8.5 For three-winding transformers, the voltage ratio measurement should be carried out on at least two pairs of windings. 8,6 For the voltage ratio measurement of semi-finished products (after insulation assembly), the voltage ratio measurement of each phase should be carried out separately for the three phases. At the same time, it should be checked whether the voltage loss relationship (winding direction and marking) of the winding is correct. 5
JB/T501-1991
8.7 The voltage ratio test after the lead wire is assembled and the total load is assembled should be carried out on each tap of each pair of two phases (such as AB/ab, BC/bc, CA/ca). If possible, it should also be verified whether the connection group and vector number are correct. 8.8 Finding of voltage ratio faults
If the voltage ratio error is found to exceed the deviation allowed by the national standard during the voltage ratio test, the product is judged to be unqualified. Determine the fault location and the number of voltages according to the following methods and procedures. 8.8.1 When only some of the taps are out of tolerance, it is determined that the high-voltage winding tapping area has wrong turns. Use a certain section of the high-voltage tap winding to measure the voltage ratio of the low-voltage winding with the designed number of turns to determine the location and number of turns of the fault. 8.8.2 When all taps are out of tolerance and the errors are the same, it should be determined first whether the high-voltage winding common section or the low-voltage winding has wrong turns. 8.8.2.1 If the error is less than the error of the low-voltage winding turns, it should be determined that the high-voltage winding common section has wrong turns. 8.8.2.2 If the fault error is greater than the error caused by one turn of any of the two windings, one of the following methods can be selected according to the coil structure. For windings with tapped ends of
secondary cylinder-type wires, the voltage ratio of the low voltage can be measured using the designed number of turns at the tapping area (note that the high voltage winding line a.
end has a higher induced voltage). If the fault phase is the same as the good phase, it means that the high voltage common line segment is wrong in turns, not the low voltage. On the contrary, it is the low voltage that is wrong;
b. If it is a continuous coil divided into two parts, the voltage ratio of the common line segment and the low voltage winding is measured using the designed number of turns. If the voltage ratio of the upper and lower halves of the faulty phase is not correct, the low-voltage winding has a wrong turn. If the voltage ratio of only one half is not correct, the high-voltage half has a wrong turn.
c. If both the high-voltage and low-voltage windings are not tapped and cannot be disconnected, a temporary winding coil can be used to measure the voltage ratio of the temporary coil with the low-voltage winding to determine the faulty winding.
8.8.3 After the general assembly, if the voltage ratio test finds that the tap position of the three phases of the product is different from the external indication, the following formula is used to determine the actual position of each phase:
fA=fAB+fCA-fBC....
fB=fBC+fAB-fCA.
fC-fCA+fBC-fAB...
In the formula: fA, fB, fC-the percentage of the tap voltage inside each phase; fAB, fBC, fCA-the percentage of the actual tap voltage of each two-phase. 9 Voltage loss relationship calibration
(1)
Voltage loss relationship calibration (also known as connection group number test) is to check whether the winding direction, connection group of the winding and the marking of the line end are correct. The connection group number is one of the conditions for the parallel operation of the transformer. There are many methods to verify the connection group number and check the voltage loss relationship between the windings. Here we only recommend the three commonly used ones, which can be selected as appropriate. 9.1 Voltage ratio bridge method
This method is the most commonly used and convenient method. The bridge itself has a receiving circuit for the common connection group number (0, 6, 11, 5). While conducting the voltage ratio test, the connection group number is also verified and the voltage loss relationship between the windings is checked. For products without a connection group number on the voltage bridge, as long as the connection between the product and the bridge is appropriately changed, the connection group number on the bridge can be used to test various connection group number products specified in GB1094.4. For specific methods, refer to Table 2. 9.2 Double voltmeter method
When the bridge used in the voltage ratio test does not have the function of determining the connection group number or other methods cannot verify the voltage vector relationship between the high and low voltages of the product, the double voltmeter method is required to verify its connection group number. 9.2.1 When using the double voltmeter method for testing, connect the wires according to Figure 2a (single-phase) or Figure 2b. (three-phase). First connect A-8, then connect the wires to the test product 6
Group numberWww.bzxZ.net
JB/T501-1991
Voltage ratio bridge method connection group number test
b—84
Bridge group
Switch position
Product connection
Group number
JB/T501-1991
Continued Table 2
Bridge group
Switch position
Note: In the table, A, B, and C respectively represent the three-phase line terminals on the high-voltage side of the product, and a, b, and c respectively represent the three-phase line terminals on the low-voltage side of the product; Ag, Bg, and Cq respectively represent the terminals on the high-voltage side of the bridge, 8., b., and c. Respectively represent the terminals on the low-voltage side of the bridge. Apply appropriate voltage (passband not exceeding 300V, generally 100V) to the high-voltage side of the bridge, and measure the voltage between X-x (single-phase) or the line-end voltages of Bb, Cb and Bc (three-phase) in turn.
Principle diagram of the test connection group for the double voltmeter method
Compare the measured voltage values (Xx or Bb, Cb and B-c) with the corresponding voltages listed in the 5th column of Table 3. If they are equal, the connection group of the test piece is labeled as the number in the 1st column. The voltage is calculated as follows:
L=Uyi+K+Ki
P=UVi+Ki
R=U.V1+v3K+K*
M=U,(K-1)
JB/T 5011991
NU.V1-K+KT..
Q=U,V1-V3K+K*
T=U,(1+K)
In the formula: L—T calculated value of corresponding voltage (column 5 in Table 3) U,-—line voltage of low voltage during test,
K--rated voltage ratio of the test piece.
Actual measurement
b-c100
161146
.b-c141
c-B193161146
Dual voltmeter method to measure the connection group
Rated voltage ratio
bB200167150133125120117
C173145
B173145
11110 9
Rb-B193161
130122
·210R
C193161
-B141120
-B173145
240Jiang
b-C200167
NcB100|88
If the voltage ratio of the tested transformer exceeds 30 times, 9.2.2
Each The difference in voltage value is very small,
21~2526~30
If you can use an auxiliary transformer,
its connection group number is Yyo or I0, connect according to Figure 3, at this time, the high-voltage end of the tested transformer should be replaced by the same-name line end of the auxiliary transformer (as shown in Figure 3, the a, b, c of the auxiliary transformer replace the A, B, C terminals), measure and compare the voltage values as before, but when calculating the values of L~T, K must be replaced K, at this time:
clock voltage generation
phase angle
sequence displacement line end
JB/T501-1991
Continued Table 3
rated voltage ratio
[Pb-B14120112105/1031021011091270R
193161
146130
115113
N bB 100
10300L
122118
Qb-B52
P6-c14112c112105102102103
Qjc-B525462|73
In the formula, K.
is the voltage ratio of the auxiliary transformer.
9.3 Light Oscilloscope Method
Tested Transformer
Auxiliary Transformer
Introducing the Connection Group Number of Auxiliary Transformer Test Wiring Diagram 106
This method is suitable for the determination of various voltage loss relationships. It is generally used for the connection group number of special B-type connections with high and low voltage losses less than 30.
When this method is used, a three-phase symmetrical voltage with a small value but sufficient to make the high and low voltage oscillators of the oscilloscope work normally is applied to the high voltage test of the test product. Introduce high and low voltages (such as AB-ab, BCbc, CA-ca) into the voltage divider box accordingly, pay special attention to the polarity of the voltage divider box and the oscillator, and then adjust the oscilloscope to make them different for easy identification. The measured waveform is shown in Figure 4. The angle difference α between the zero crossing of the positive half-wave of the high voltage voltage and the low voltage voltage is the angle at which the low voltage is ahead or behind the high voltage. The three-phase transformer should be measured at least on two pairs of corresponding line ends. If there is any doubt about the measurement result, the correctness of the test wiring should be verified on a product with a known vector relationship.(Three-phase) wiring. First connect A-8, then test product 6
Group number
JB/T501-1991
Voltage ratio bridge method connection group number test
b—84
Bridge group
Switch position
Product connection
Group number
JB/T501-1991
Continued Table 2
Bridge group
Switch position
Note: In the table, A, B, and C respectively represent the three-phase line terminals on the high-voltage side of the product, and a, b, and c respectively represent the three-phase line terminals on the low-voltage side of the product; Ag, Bg, and Cq respectively represent the terminals on the high-voltage side of the bridge, and 8., b., and c. respectively represent the terminals on the low-voltage side of the bridge. Apply appropriate voltage (passband not exceeding 300V, generally 100V) to the high-voltage side of the tester, and measure the voltage between X-x (single-phase) or the line-end voltages of Bb, Cb and Bc (three-phase) in turn.
Principle diagram of connection group for double voltmeter method test
Compare the measured voltage values (Xx or Bb, Cb and B-c) with the corresponding voltages listed in the 5th column of Table 3. If they are equal, the connection group of the test piece is labeled as the number in the 1st column. The voltage is calculated as follows:
L=Uyi+K+Ki
P=UVi+Ki
R=U.V1+v3K+K*
M=U,(K-1)
JB/T 5011991
NU.V1-K+KT..
Q=U,V1-V3K+K*
T=U,(1+K)
In the formula: L—T calculated value of corresponding voltage (column 5 in Table 3) U,-—line voltage of low voltage during test,
K--rated voltage ratio of the test piece.
Actual measurement
b-c100
161146
.b-c141
c-B193161146
Dual voltmeter method to measure the connection group
Rated voltage ratio
bB200167150133125120117
C173145
B173145
11110 9
Rb-B193161
130122
·210R
C193161
-B141120
-B173145
240Jiang
b-C200167
NcB100|88
If the voltage ratio of the transformer under test exceeds 30 times, 9.2.2
Each The difference in voltage value is very small,
21~2526~30
If you can use an auxiliary transformer,
its connection group number is Yyo or I0, connect according to Figure 3, at this time, the high-voltage end of the tested transformer should be replaced by the same-name line end of the auxiliary transformer (as shown in Figure 3, the a, b, c of the auxiliary transformer replace the A, B, C terminals), measure and compare the voltage values as before, but when calculating the values of L~T, K must be replaced K, at this time:
clock voltage generation
phase angle
sequence displacement line end
JB/T501-1991
Continued Table 3
rated voltage ratio
[Pb-B14120112105/1031021011091270R
193161
146130
115113
N bB 100
10300L
122118
Qb-B52
P6-c14112c112105102102103
Qjc-B525462|73
In the formula, K.
is the voltage ratio of the auxiliary transformer.
9.3 Light Oscilloscope Method
Tested Transformer
Auxiliary Transformer
Introducing the Connection Group Number of Auxiliary Transformer Test Wiring Diagram 106
This method is suitable for the determination of various voltage loss relationships. It is generally used for the connection group number of special B-type connections with high and low voltage losses less than 30.
When this method is used, a three-phase symmetrical voltage with a small value but sufficient to make the high and low voltage oscillators of the oscilloscope work normally is applied to the high voltage test of the test product. Introduce high and low voltages (such as AB-ab, BCbc, CA-ca) into the voltage divider box accordingly, pay special attention to the polarity of the voltage divider box and the oscillator, and then adjust the oscilloscope to make them different for easy identification. The measured waveform is shown in Figure 4. The angle difference α between the zero crossing of the positive half-wave of the high voltage voltage and the low voltage voltage is the angle at which the low voltage is ahead or behind the high voltage. The three-phase transformer should be measured at least on two pairs of corresponding line ends. If there is any doubt about the measurement result, the correctness of the test wiring should be verified on a product with a known vector relationship.(Three-phase) wiring. First connect A-8, then test product 6
Group number
JB/T501-1991
Voltage ratio bridge method connection group number test
b—84
Bridge group
Switch position
Product connection
Group number
JB/T501-1991
Continued Table 2
Bridge group
Switch position
Note: In the table, A, B, and C respectively represent the three-phase line terminals on the high-voltage side of the product, and a, b, and c respectively represent the three-phase line terminals on the low-voltage side of the product; Ag, Bg, and Cq respectively represent the terminals on the high-voltage side of the bridge, and 8., b., and c. respectively represent the terminals on the low-voltage side of the bridge. Apply appropriate voltage (passband not exceeding 300V, generally 100V) to the high-voltage side of the tester, and measure the voltage between X-x (single-phase) or the line-end voltages of Bb, Cb and Bc (three-phase) in turn.
Principle diagram of connection group for double voltmeter method test
Compare the measured voltage values (Xx or Bb, Cb and B-c) with the corresponding voltages listed in the 5th column of Table 3. If they are equal, the connection group of the test piece is labeled as the number in the 1st column. The voltage is calculated as follows:
L=Uyi+K+Ki
P=UVi+Ki
R=U.V1+v3K+K*
M=U,(K-1)
JB/T 5011991
NU.V1-K+KT..
Q=U,V1-V3K+K*
T=U,(1+K)
In the formula: L—T calculated value of corresponding voltage (column 5 in Table 3) U,-—line voltage of low voltage during test,
K--rated voltage ratio of the test piece.
Actual measurement
b-c100
161146
.b-c141
c-B193161146
Dual voltmeter method to measure the connection group
Rated voltage ratio
bB200167150133125120117
C173145
B173145
11110 9
Rb-B193161
130122
·210R
C193161
-B141120
-B173145
240Jiang
b-C200167
NcB100|88
If the voltage ratio of the transformer under test exceeds 30 times, 9.2.2
Each The difference in voltage value is very small,
21~2526~30
If you can use an auxiliary transformer,
its connection group number is Yyo or I0, connect according to Figure 3, at this time, the high-voltage end of the tested transformer should be replaced by the same-name line end of the auxiliary transformer (as shown in Figure 3, the a, b, c of the auxiliary transformer replace the A, B, C terminals), measure and compare the voltage values as before, but when calculating the values of L~T, K must be replaced K, at this time:
clock voltage generation
phase angle
sequence displacement line end
JB/T501-1991
Continued Table 3
rated voltage ratio
[Pb-B14120112105/1031021011091270R
193161
146130
115113
N bB 100
10300L
122118
Qb-B52
P6-c14112c112105102102103
Qjc-B525462|73
In the formula, K.
is the voltage ratio of the auxiliary transformer.
9.3 Light Oscilloscope Method
Tested Transformer
Auxiliary Transformer
Introducing the Connection Group Number of Auxiliary Transformer Test Wiring Diagram 106
This method is suitable for the determination of various voltage loss relationships. It is generally used for the connection group number of special B-type connections with high and low voltage losses less than 30.
When this method is used, a three-phase symmetrical voltage with a small value but sufficient to make the high and low voltage oscillators of the oscilloscope work normally is applied to the high voltage test of the test product. Introduce high and low voltages (such as AB-ab, BCbc, CA-ca) into the voltage divider box accordingly, pay special attention to the polarity of the voltage divider box and the oscillator, and then adjust the oscilloscope to make them different for easy identification. The measured waveform is shown in Figure 4. The angle difference α between the zero crossing of the positive half-wave of the high voltage voltage and the low voltage voltage is the angle at which the low voltage is ahead or behind the high voltage. The three-phase transformer should be measured at least on two pairs of corresponding line ends. If there is any doubt about the measurement result, the correctness of the test wiring should be verified on a product with a known vector relationship.3-ray oscilloscope method
Tested transformer
Auxiliary transformer
Introducing the connection group number of the auxiliary transformer Test wiring diagram 106
This method is suitable for the determination of various voltage loss relationships. It is generally used for the connection group number of special connections with high and low voltage losses less than 30.
When using this method, a three-phase symmetrical voltage with a small value but sufficient to make the high and low voltage oscillators of the oscilloscope work normally is applied to the high voltage of the test product. The voltages of the high voltage (such as AB-ab, BCbc, CA-ca) are introduced into the voltage divider box, and special attention is paid to the polarity of the voltage divider box and the oscillator. Then adjust the oscilloscope to make a difference for easy identification. The measured waveform is shown in Figure 4. The angle difference α between the zero crossing of the positive half-wave of the high voltage and the low voltage is the angle at which the low voltage is ahead or behind the high voltage. The three-phase transformer should be measured at least on two pairs of corresponding line ends. If there is any doubt about the measurement result, the correctness of the test wiring should be verified on a product with a known vector relationship.3-ray oscilloscope method
Tested transformer
Auxiliary transformer
Introducing the connection group number of the auxiliary transformer Test wiring diagram 106
This method is suitable for the determination of various voltage loss relationships. It is generally used for the connection group number of special connections with high and low voltage losses less than 30.
When using this method, a three-phase symmetrical voltage with a small value but sufficient to make the high and low voltage oscillators of the oscilloscope work normally is applied to the high voltage of the test product. The voltages of the high voltage (such as AB-ab, BCbc, CA-ca) are introduced into the voltage divider box, and special attention is paid to the polarity of the voltage divider box and the oscillator. Then adjust the oscilloscope to make a difference for easy identification. The measured waveform is shown in Figure 4. The angle difference α between the zero crossing of the positive half-wave of the high voltage and the low voltage is the angle at which the low voltage is ahead or behind the high voltage. The three-phase transformer should be measured at least on two pairs of corresponding line ends. If there is any doubt about the measurement result, the correctness of the test wiring should be verified on a product with a known vector relationship.
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