CN102735959A - On-line ultrahigh-voltage line power transformer test method - Google Patents

Abstract

A test method for an ultra-high voltage line power transformer without disconnection, the specific steps are as follows: measure the "raw data" of disconnection and the "basic data" of non-disconnection; measure the insulation resistance R of the winding; analyze the insulation resistance value R of the winding; Measure the active current I _p , reactive current I _k and dielectric loss factor tanδ of each winding; analyze the dielectric loss factor tanδ; measure the capacitance C of the capacitive bushing; analyze the capacitance C of the capacitive bushing; measure the winding leakage current I; analyze the winding leakage current I. The advantages are: the measurement result is accurate, the safety of the operator can be guaranteed, the equipment damage can be avoided, and the safety is good.

Description

Test method for extra-high voltage line power transformer without disconnection

technical field

The invention relates to a method for conducting preventive tests on power transformers, in particular to a test method for power transformers with ultra-high voltage lines without disconnecting the wires.

Background technique

In order to discover the hidden dangers of power transmission and transformation equipment in operation and prevent accidents or equipment damage, it is necessary to conduct preventive tests on power transmission and transformation equipment. At present, the commonly used preventive test method for transformers is to remove the connections on each side of the transformer, and then perform routine measurements on various data of the transformer. The process of disassembling and assembling the leads is dangerous, labor-intensive and time-consuming, and the equipment is easily damaged. For avoiding the generation of above-mentioned phenomenon, disclose a kind of test method of power transformer without disconnection among CN101354418 B. This method requires that before the transformer is put into operation, a set of "raw data" should be measured without connecting the leads on each side, and a set of "basic data" should be measured after connecting the leads on the upper side. Parts, the insulation resistance of each winding and the bushing, and the leakage current of the bushing and the winding, the dielectric loss factor and the capacitance value of the bushing and the coil. Its disadvantages are: 1. Due to the dense power facilities around the power transformer of 500kV and above lines, and the high voltage of the alternating current passing through the surrounding power facilities, it is easy to generate AC interference current to interfere with the instrument, the instrument display is unstable, and the measurement result is inaccurate , or even unable to read; 2. The current passing through the power facility is large, which will generate static electricity and damage the operator or experimental equipment, which is poor in safety. 3. In the conventional method, the dielectric loss measurement adopts the reverse connection method. The data measured by this method include the dielectric loss of the CTV of the transformer and the lead-out line of the bushing, and the dielectric loss of the CTV and the lead-out line of the 500kV transformer is relatively large. It cannot be ignored, resulting in a large error in the measurement results; 4. When measuring the capacitance of the primary side and secondary side of the winding, the inductance and no-load loss of the winding will affect the measurement results. According to the conventional test method disclosed in CN101354418 B without disconnecting the lead wire, it is difficult to carry out the test without disconnecting the wire of 500kV and above ultra-high voltage line power transformer.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for testing an ultra-high-voltage line power transformer without disconnecting wires with accurate measurement results, which can ensure the safety of operators, avoid equipment damage, and have good safety.

The present invention is achieved like this:

A test method for power transformers of ultra-high voltage lines without disconnecting the wires, which is special in that the specific steps are as follows:

1) Measure the insulation resistance between the transformer core, clamps, windings and bushings before the transformer is put into operation, as well as the leakage current, dielectric loss factor and capacitance of the bushings and windings, and use them as "raw data ", after connecting the side wires of the transformer, measure the above data again as the "basic data";

2) Measure the insulation resistance R of the winding: ground the G terminal of the megohmmeter, respectively connect the L terminal of the megohmmeter to the winding to be tested, the iron core and the clamp of the transformer, and connect the L terminal to the winding to be tested of the transformer. A one-way diode D is connected in series, and the L end is grounded after passing through a capacitor _C11 . The anode of the one-way diode D is connected to the L end, and the E end of the megohmmeter is connected to the non-test winding of the transformer. The test windings are high and medium voltage windings, low voltage windings, and no windings respectively, and the insulation resistance R ₁ of the high and medium voltage windings and the iron core to the low voltage winding, the insulation resistance R ₂ of the low voltage winding and the iron core to the high and medium voltage windings, and the insulation resistance of the iron core to the high and high The insulation resistance R ₃ of the low-voltage winding, the test result is used as the insulation resistance value in the "measurement data";

3) Analyze the insulation resistance value R of the winding: compare the insulation resistance value in the "measured data" with the corresponding resistance value in the "raw data", when the insulation resistance value in the "measured data" is greater than or equal to the value corresponding to the "raw data" When the insulation resistance value is 1.3 times, the insulation between the windings is good. When at least one group of insulation resistance values in the "measured data" is less than 1.3 times the insulation resistance value corresponding to the "raw data", but greater than the insulation resistance value corresponding to the "raw data" For the resistance value, compare it with the insulation resistance value in the "basic data". When the insulation resistance value in the "measurement data" is greater than or equal to 0.7 times the corresponding insulation resistance value in the "basic data", the insulation between the windings is good. When one or two sets of insulation resistance values in the "measurement data" are less than 0.7 times the corresponding insulation resistance value in the "basic data", carry out the transformer oil test to eliminate hidden dangers in the transformer. When the "measurement data" in When the insulation resistance values are all less than 0.7 times the corresponding insulation resistance value in the "basic data", or the insulation resistance value in the "measurement data" is less than or equal to the corresponding insulation resistance value in the "raw data", return the transformer to the factory for repair;

4) Measure the active current I _p , reactive current I _k and dielectric loss factor tanδ of each winding: use the Xilin bridge of positive connection method to apply voltage to the high and medium voltage windings respectively, and measure the passage of low voltage windings, iron cores and clamps Active current I _p1 and reactive current I _k1 , apply voltage to low-voltage windings, measure active current I _p2 and reactive current I _k2 passing through high- and medium-voltage windings, iron cores, and clamps, and apply voltage to high- and medium-voltage and low-voltage windings , measure the active current I _p3 and reactive current I _k3 passing through the iron core and the clamp, and get three sets of data, according to the formula:

                   （I）

(I)

Calculate the ratio between the active current I _p and the reactive current I _k in each group of data, and obtain the dielectric loss factor tanδ ₁ of the high and medium voltage windings to the low voltage windings, iron cores and clamps, and the low voltage windings to the high and medium voltage windings, iron cores And the dielectric loss factor tanδ ₂ of the clip, and the dielectric loss factor tanδ ₃ of the high, medium and low voltage windings to the iron core and the clip are used as the dielectric loss factor in the "measurement data";

5) Analyze the dielectric loss factor tanδ: compare the dielectric loss factors tanδ ₁ , tanδ ₂ , and tanδ ₃ of the "measured data" with the corresponding dielectric loss factors in the "raw data", when the absolute value of the difference between the two is less than or equal to the "original When the corresponding dielectric loss factor is 5% of the "data", the dielectric loss factor is normal. When the absolute value of the difference between the two is greater than 5% of the corresponding dielectric loss factor in the "raw data", perform troubleshooting;

6) Measure the capacitance C of the capacitive bushing: Connect the high, medium and low voltage windings of the primary side bushing and the secondary side bushing respectively in series, and use the Xilin bridge to measure the reactive power Q ₁ of the primary bushing and the secondary bushing respectively. The reactive power Q ₂ of the tube, according to the formula:

                      （II）

(II)

Calculate the capacitance C ₁ of the primary side bushing and the capacitance C ₂ of the secondary bushing as the capacitance of the capacitive bushing in the "measurement data", where ω is the angular frequency of the transformer, and U is the rated voltage of the transformer;

7) Analyze the capacitance C of the capacitive bushing: compare the capacitance of the capacitive bushing in the "measurement data" with the capacitance of the capacitive bushing in the "raw data", when When the absolute value of the difference between the two is less than or equal to 5% of the corresponding capacitance in the "raw data", it is considered that the capacitive bushing is normal; when the difference between the two is greater than 5% of the corresponding capacitance in the "raw data", perform troubleshooting;

8) Measure the leakage current I of the winding: connect the microammeter in series with the resistor R ₁₁ and connect it in parallel with the capacitor C ₁₂ , then connect the positive electrode of the microammeter A to the ground, and connect the high voltage output terminal of the DC generator to the high and medium voltage winding respectively, and the resistance input The terminal is connected with the low-voltage winding, iron core, and clamp to obtain the leakage current I ₁ of the high- and medium-voltage winding to the low-voltage winding, iron core, and clamp. , iron core, and clips are connected to obtain the leakage current I ₂ of the low-voltage winding to the high- and medium-voltage windings, iron cores, and clips. Connect the clamps to obtain the leakage current I ₃ of the high, medium and low voltage windings to the iron core and the clamps, and use the above measurement results as the leakage current in the "measurement data";

9) Analyze the winding leakage current I: compare the measured winding leakage current I ₁ and I ₂ with the winding leakage current in the "raw data", when the absolute value of the difference between the two is less than or equal to the corresponding leakage current in the "raw data" When 5% of the leakage current is within the safe range, when the absolute value of the difference between the two is greater than 5% of the leakage current corresponding to the "raw data", perform troubleshooting.

The rated current of the megohmmeter is ≥0.8mA, so as to prevent the megohmmeter from being damaged by the current.

The output voltage of the E terminal of the megohmmeter is 4000V-6000V to ensure accurate readings.

The output voltage of the high-voltage output terminal of the DC generator is 20kV-40kV to ensure measurement accuracy.

The forward conduction current of the unidirectional diode D is ≥3A, so as to reduce the influence on the measurement result.

The rated voltage of the capacitors C ₁₁ and C ₁₂ is greater than or equal to 500kV to avoid breakdown of the capacitors.

The resistance value of the resistor R ₁₁ is greater than or equal to 1 MΩ, so as to ensure the safety of the microammeter.

The beneficial effects of the present invention are:

1. Since the insulation resistance between the transformer core, clips, windings and bushings, as well as the leakage current, dielectric loss factor and capacitance value of the bushings and windings are measured before the transformer is put into operation without disconnecting the test , and use it as the "original data", after connecting the side wires of the transformer, measure the above data again, as the "basic data", and compare the "measured data" with the "raw data" and "basic data" when performing the test without disconnecting the wires. After the comparison, the diagnosis result is obtained, and the obtained diagnosis result is true and credible.

2. Since there is a one-way diode in series between the L terminal of the megohmmeter and the winding to be tested of the transformer, the anode of the one-way diode is connected to the L terminal, and the one-way diode limits the flow direction of the current to prevent the megohm from being destroyed by the current impact. Table, to avoid equipment damage.

3. Since the L terminal of the megohmmeter and the one-way diode are connected in parallel to the capacitor and then grounded, the capacitor can filter out the interference generated by the surrounding power facilities, and the measurement result is accurate; at the same time, the capacitor can effectively prevent the phenomenon of static electricity hitting people. , to ensure the safety of the operator.

4. Since the positive connection method is adopted in the measurement of the dielectric loss, the influence of the CVT and bushing lead-out wires to the ground dielectric loss on the test results is eliminated, and the error of the measurement results is reduced.

5. Since the windings on the primary side and the secondary side are respectively connected in series to measure the capacitance, the measurement error caused by the inductance and no-load loss of the windings is reduced.

6. Since the resistance of the microammeter is connected in parallel with the capacitor in series, the influence of the AC interference current on the reading of the microammeter is avoided, and the test result is more accurate.

Description of drawings

Fig. 1 is the wiring diagram of step 2 among the present invention;

Fig. 2 is a schematic diagram of wiring of a microammeter, a resistor R ₁₁ and a capacitor C ₁₂ in step 8 of the present invention.

In the figure: high and medium voltage winding 1, low voltage winding 2, iron core 3, megohmmeter 4, microampere meter 5.

Detailed ways

As shown in the figure, the specific steps of the ultra-high voltage line power transformer test method without disconnection are as follows:

The specific steps of the ultra-high voltage line power transformer test method without disconnection are as follows:

1) Measure the insulation resistance between the transformer core 3, clamps, each winding and the bushing, as well as the leakage current, dielectric loss factor and capacitance value of the bushing and each winding before the transformer is put into operation, and use it as the "original Data", after connecting the side wires of the transformer, measure the above data again as the "basic data".

2) Measure the insulation resistance R of the winding: ground the G terminal of the megohmmeter 4, connect the L terminal of the megohmmeter 4 with the winding to be tested, the iron core 3 and the clamp of the transformer respectively, and connect the L terminal with the transformer to be tested A unidirectional diode D is connected in series between the windings. In this embodiment, the forward current of the unidirectional diode D is 3A, and the L terminal is grounded after passing through the capacitor _C11 . In this embodiment, the rated voltage of the capacitor _C11 is 600kV, so The anode of the one-way diode D described above is connected with the L end, and the E end of the megohmmeter 4 is connected with the non-tested winding of the transformer, and the described winding to be tested is respectively high and medium voltage winding 1, low voltage winding 2, and no winding. The insulation resistance R 1 of high and medium voltage winding 1 and iron core 3 to low voltage winding ₂ , the insulation resistance R ₂ of low voltage winding 2 and iron core 3 to high and medium voltage winding 1, and the insulation resistance of iron core 3 to high, medium and low voltage winding 1 and 2 are respectively obtained Resistance R ₃ , the test result is used as the insulation resistance value in "measurement data". The rated current of the megohmmeter 4 used in this step is ≥0.8mA, and the output voltage of the E terminal is 4000V-6000V. In this embodiment, the rated current of the megger 4 is 0.8mA, and the output voltage of the E terminal is 5000V.

3) Analyze the insulation resistance value R of the winding: compare the insulation resistance value in the "measured data" with the corresponding resistance value in the "raw data", when the insulation resistance value in the "measured data" is greater than or equal to the value corresponding to the "raw data" When the insulation resistance value is 1.3 times, the insulation between the windings is good. When at least one group of insulation resistance values in the "measured data" is less than 1.3 times the insulation resistance value corresponding to the "raw data", but greater than the insulation resistance value corresponding to the "raw data" For the resistance value, compare it with the insulation resistance value in the "basic data". When the insulation resistance value in the "measurement data" is greater than or equal to 0.7 times the corresponding insulation resistance value in the "basic data", the insulation between the windings is good. When one or two sets of insulation resistance values in the "measurement data" are less than 0.7 times the corresponding insulation resistance value in the "basic data", carry out the transformer oil test to eliminate hidden dangers in the transformer. When the "measurement data" in When the insulation resistance values are all less than 0.7 times the corresponding insulation resistance value in the "basic data", or the insulation resistance value in the "measurement data" is less than or equal to the corresponding insulation resistance value in the "raw data", return the transformer to the factory for repair.

4) Measure the active current I _p , reactive current I _k and dielectric loss factor tanδ of each winding: adopt the Xilin bridge of positive connection, apply voltage to the high and medium voltage winding 1 respectively, and measure the low voltage winding 2, iron core 3, clip The active current I _p1 and reactive current I _k1 passing through the parts, apply voltage to the low voltage winding 2, measure the active current I _p2 and reactive current I _k2 passing through the high and medium voltage winding 1, iron core 3, and the clip, Apply voltage to the high-voltage and low-voltage winding 2, measure the active current I _p3 and reactive current I _k3 passing through the iron core 3 and the clamp, and obtain three sets of data, according to the formula:

                   （I）

(I)

Calculate the ratio between the active current I _p and the reactive current I _k in each group of data, and obtain the dielectric loss factor tanδ ₁ of the high and medium voltage winding 1 to the low voltage winding 2, the iron core 3 and the clip, and the low voltage winding 2 to the high and medium voltage The dielectric loss factor tanδ ₂ of winding 1, iron core 3 and clip, and the dielectric loss factor tanδ 3 of _high , medium and low voltage winding 1, 2 pairs of iron core 3 and clip are used as the dielectric loss factor in "measurement data".

5) Analyze the dielectric loss factor tanδ: compare the dielectric loss factors tanδ ₁ , tanδ ₂ , and tanδ ₃ of the "measured data" with the corresponding dielectric loss factors in the "raw data", when the absolute value of the difference between the two is less than or equal to the "original When the corresponding dielectric loss factor is 5% in the "data", the dielectric loss factor is normal. When the absolute value of the difference between the two is greater than 5% of the corresponding dielectric loss factor in the "raw data", perform troubleshooting.

6) Measure the capacitance C of the capacitive bushing: Connect the high, medium and low voltage windings 1 and 2 of the primary side bushing and the secondary side bushing respectively in series, and measure the reactive power Q ₁ , The reactive power Q ₂ of the secondary bushing, according to the formula:

                      （II）

(II)

Calculate the capacitance C ₁ of the primary side bushing and the capacitance C ₂ of the secondary bushing as the capacitance of the capacitive bushing in the "measurement data", where ω is the angular frequency of the transformer, and U is the rated voltage of the transformer.

7) Analyze the capacitance C of the capacitive bushing: compare the capacitance of the capacitive bushing in the "measurement data" with the capacitance of the capacitive bushing in the "raw data", when When the absolute value of the difference between the two is less than or equal to 5% of the corresponding capacitance in the "raw data", it is considered that the capacitive bushing is normal; when the difference between the two is greater than 5% of the corresponding capacitance in the "raw data", Do troubleshooting.

8) Measuring the leakage current I of the winding: connect the microammeter 5 in series with the resistor _R11 and then connect it in parallel with the capacitor _C12 . In this embodiment, the resistance of the resistor is 2MΩ, and the rated voltage of the capacitor is 500kV. Then connect the positive pole of the microampere meter 5A to the ground, and respectively connect the high voltage output end of the DC generator to the high and medium voltage winding 1, and connect the resistance input end to the low voltage winding 2, the iron core 3, and the clip to obtain the high and medium voltage winding 1 and the low voltage winding 2 , iron core 3, leakage current I ₁ of the clip, connect the high voltage output end of the DC generator to the low voltage winding 2, and connect the resistance input end to the high and medium voltage winding 1, the iron core 3, and the clip to obtain the pair of low voltage winding 2 to the high and medium voltage For the leakage current I ₂ of winding 1, iron core 3, and clamps, connect the high-voltage output end of the DC generator to high-middle-voltage winding 1 and low-voltage winding 2, and connect the resistance input end to iron core 3 and clamps to obtain high-middle-voltage and low-voltage windings 2 For the leakage current I ₃ of the iron core 3 and the clip, use the above measurement results as the leakage current in the "measurement data"; the voltage at the high-voltage output terminal of the DC generator in this step is 30kV.

9) Analyze the winding leakage current I: compare the measured winding leakage current I ₁ and I ₂ with the winding leakage current in the "raw data", when the absolute value of the difference between the two is less than or equal to the corresponding leakage current in the "raw data" When 5% of the leakage current is within the safe range, when the absolute value of the difference between the two is greater than 5% of the leakage current corresponding to the "raw data", perform troubleshooting.

For checking the advantage that the present invention's measurement result is accurate, carry out comparative test, adopt three cover transformers in the test, respectively with the method for removing lead wire test, routine not tearing down lead wire test method, the method provided by the present invention at 20 ℃, relative humidity 35% Experiments were carried out under these conditions, and three sets of data were obtained:

1. The method of removing the lead wire test:

1), insulation resistance R

the Measured value at 15S (MΩ) Measured value at 1min (MΩ) Measured value at 2min (MΩ) High and medium voltage winding → low voltage winding and iron core 18225 22671 31006 Low voltage winding → high and medium voltage winding and iron core 5412 9504 12235 Iron core→high, medium and low voltage winding 3601 5820 7872

2) Dielectric loss factor tanδ

the Dielectric loss factor tanδ (%) High and medium voltage winding → low voltage winding and iron core 0.09 Low voltage winding → high and medium voltage winding and iron core 0.11 Iron core→high, medium and low voltage winding 0.28

3) Capacitance C

the Capacitance C (pF) High and medium voltage winding → low voltage winding and iron core 2340.1 Low voltage winding → high and medium voltage winding and iron core 9642.1 Iron core→high, medium and low voltage winding 2332.6

4), winding leakage current I

the Leakage current I (μA) High and medium voltage winding → low voltage winding and iron core 4.8 Low voltage winding → high and medium voltage winding and iron core 4.2 Iron core→high, medium and low voltage winding 8.3

2. Conventional test method without removing the lead wire:

1), insulation resistance R

the Measured value at 15S (MΩ) Measured value at 1min (MΩ) Measured value at 2min (MΩ) High and medium voltage winding → low voltage winding and iron core 22679 28518 39298 Low voltage winding → high and medium voltage winding and iron core 8051 13425 16697 Iron core→high, medium and low voltage winding 4550 8745 11297

2) Dielectric loss factor tanδ

the Dielectric loss factor tanδ (%) High and medium voltage winding → low voltage winding and iron core 0.12 Low voltage winding → high and medium voltage winding and iron core 0.18 Iron core→high, medium and low voltage winding 0.27

3) Capacitance C

the Capacitance C (pF) High and medium voltage winding → low voltage winding and iron core 6837.0 Low voltage winding → high and medium voltage winding and iron core 10178.8 Iron core→high, medium and low voltage winding 2810.0

4), winding leakage current I

the Leakage current I (μA) High and medium voltage winding → low voltage winding and iron core 4.5 Low voltage winding → high and medium voltage winding and iron core 4.5 Iron core→high, medium and low voltage winding 8.8

3. The method provided by the invention:

1), insulation resistance R

the Measured value at 15S (MΩ) Measured value at 1min (MΩ) Measured value at 2min (MΩ) High and medium voltage winding → low voltage winding and iron core 21531 (MΩ) 26979 (MΩ) 35776 (MΩ) Low voltage winding → high and medium voltage winding and iron core 6390 11691 14681 Iron core→high, medium and low voltage winding 3250 6790 (MΩ) 9290

2) Dielectric loss factor tanδ

the Dielectric loss factor tanδ (%) High and medium voltage winding → low voltage winding and iron core 4.3 Low voltage winding → high and medium voltage winding and iron core 4.4 Iron core→high, medium and low voltage winding 8.1

3) Capacitance C

the Capacitance C (pF) High and medium voltage winding → low voltage winding and iron core 2345.7 Low voltage winding → high and medium voltage winding and iron core 9631.9 Iron core→high, medium and low voltage winding 2332.8

4), winding leakage current I

the Leakage current I (μA) High and medium voltage winding → low voltage winding and iron core 6837.0 Low voltage winding → high and medium voltage winding and iron core 10178.8 Iron core→high, medium and low voltage winding 2810.0

According to the analysis of experimental results, the data obtained by the method provided by the present invention is closer to the data obtained by removing the lead wire test than the data obtained by the conventional test method without removing the lead wire, that is, closer to the true value of the 500kV transformer, which proves that the measurement result is more accurate. the

Claims (7)

1. A method for testing the power transformer of an ultra-high voltage line without disconnecting the wires, characterized in that: 1) Measure the insulation resistance between the transformer core, clamps, windings and bushings before the transformer is put into operation, as well as the leakage current, dielectric loss factor and capacitance of the bushings and windings, and use them as "raw data ", after connecting the side wires of the transformer, measure the above data again as the "basic data"; 2) Measure the insulation resistance R of the winding: ground the G terminal of the megohmmeter, respectively connect the L terminal of the megohmmeter to the winding to be tested, the iron core and the clamp of the transformer, and connect the L terminal to the winding to be tested of the transformer. A one-way diode D is connected in series, and the L terminal is grounded after passing through a capacitor _C11 . The anode of the one-way diode D is connected to the L terminal, and the E terminal of the megohmmeter is connected to the non-test winding of the transformer. The test windings are high and medium voltage windings, low voltage windings, and no windings respectively, and the insulation resistance R ₁ of the high and medium voltage windings and the iron core to the low voltage winding, the insulation resistance R ₂ of the low voltage winding and the iron core to the high and medium voltage windings, and the insulation resistance of the iron core to the high and high The insulation resistance R ₃ of the low-voltage winding, the test result is used as the insulation resistance value in the "measurement data"; 3) Analyze the insulation resistance value R of the winding: compare the insulation resistance value in the "measured data" with the corresponding resistance value in the "raw data", when the insulation resistance value in the "measured data" is greater than or equal to the value corresponding to the "raw data" When the insulation resistance value is 1.3 times, the insulation between the windings is good. When at least one group of insulation resistance values in the "measured data" is less than 1.3 times the insulation resistance value corresponding to the "raw data", but greater than the insulation resistance value corresponding to the "raw data" For the resistance value, compare it with the insulation resistance value in the "basic data". When the insulation resistance value in the "measurement data" is greater than or equal to 0.7 times the corresponding insulation resistance value in the "basic data", the insulation between the windings is good. When one or two sets of insulation resistance values in the "measurement data" are less than 0.7 times the corresponding insulation resistance value in the "basic data", carry out the transformer oil test to eliminate hidden dangers in the transformer. When the "measurement data" in When the insulation resistance values are all less than 0.7 times the corresponding insulation resistance value in the "basic data", or the insulation resistance value in the "measurement data" is less than or equal to the corresponding insulation resistance value in the "raw data", return the transformer to the factory for repair; 4) Measure the active current I _p , reactive current I _k and dielectric loss factor tanδ of each winding: use the Xilin bridge of positive connection method to apply voltage to the high and medium voltage windings respectively, and measure the passage of low voltage windings, iron cores and clamps Active current I _p1 and reactive current I _k1 , apply voltage to low-voltage windings, measure active current I _p2 and reactive current I _k2 passing through high- and medium-voltage windings, iron cores, and clamps, and apply voltage to high- and medium-voltage and low-voltage windings , measure the active current I _p3 and reactive current I _k3 passing through the iron core and the clamp, and get three sets of data, according to the formula: (I) Calculate the ratio between the active current I _p and the reactive current I _k in each group of data, and obtain the dielectric loss factor tanδ ₁ of the high and medium voltage windings to the low voltage windings, iron cores and clamps, and the low voltage windings to the high and medium voltage windings, iron cores And the dielectric loss factor tanδ ₂ of the clip, and the dielectric loss factor tanδ ₃ of the high, medium and low voltage windings to the iron core and the clip are used as the dielectric loss factor in the "measurement data"; 5) Analyze the dielectric loss factor tanδ: compare the dielectric loss factors tanδ ₁ , tanδ ₂ , and tanδ ₃ of the "measured data" with the corresponding dielectric loss factors in the "raw data", when the absolute value of the difference between the two is less than or equal to the "original When the corresponding dielectric loss factor is 5% of the "data", the dielectric loss factor is normal. When the absolute value of the difference between the two is greater than 5% of the corresponding dielectric loss factor in the "raw data", perform troubleshooting; 6) Measure the capacitance C of the capacitive bushing: Connect the high, medium and low voltage windings of the primary side bushing and the secondary side bushing respectively in series, and use the Xilin bridge to measure the reactive power Q ₁ of the primary bushing and the secondary bushing respectively. The reactive power Q ₂ of the tube, according to the formula:

(II) Calculate the capacitance C ₁ of the primary side bushing and the capacitance C ₂ of the secondary bushing as the capacitance of the capacitive bushing in the "measurement data", where ω is the angular frequency of the transformer, and U is the rated voltage of the transformer; 7) Analyze the capacitance C of the capacitive bushing: compare the capacitance of the capacitive bushing in the "measurement data" with the capacitance of the capacitive bushing in the "raw data", when When the absolute value of the difference between the two is less than or equal to 5% of the corresponding capacitance in the "raw data", it is considered that the capacitive bushing is normal; when the difference between the two is greater than 5% of the corresponding capacitance in the "raw data", perform troubleshooting; 8) Measure the leakage current I of the winding: connect the microammeter in series with the resistor R ₁₁ and connect it in parallel with the capacitor C ₁₂ , then connect the positive electrode of the microammeter A to the ground, and connect the high voltage output terminal of the DC generator to the high and medium voltage winding respectively, and the resistance input The terminal is connected with the low-voltage winding, iron core, and clamp to obtain the leakage current I ₁ of the high- and medium-voltage winding to the low-voltage winding, iron core, and clamp. , iron core, and clips are connected to obtain the leakage current I ₂ of the low-voltage winding to the high- and medium-voltage windings, iron cores, and clips. Connect the clamps to obtain the leakage current I ₃ of the high, medium and low voltage windings to the iron core and the clamps, and use the above measurement results as the leakage current in the "measurement data"; 9) Analyze the winding leakage current I: compare the measured winding leakage current I ₁ and I ₂ with the winding leakage current in the "raw data", when the absolute value of the difference between the two is less than or equal to the corresponding leakage current in the "raw data" When 5% of the leakage current is within the safe range, when the absolute value of the difference between the two is greater than 5% of the leakage current corresponding to the "raw data", perform troubleshooting. 2. The non-disconnection test method for an ultra-high voltage line power transformer according to claim 1, characterized in that: the rated current of the megohmmeter is ≥0.8mA. 3. The method for testing the ultra-high voltage line power transformer without disconnection according to claim 1, characterized in that: the output voltage of the terminal E of the megohmmeter is 4000V-6000V. 4. The method for testing the power transformer of an ultra-high voltage line without disconnection according to claim 1, characterized in that: the output voltage of the high voltage output terminal of the DC generator is 20kV-40kV. 5. The non-disconnection test method of the ultra-high voltage line power transformer according to claim 1, characterized in that: The forward conduction current of the unidirectional diode D is ≥ 3A. 6. The method for testing the power transformer of an ultra-high voltage line without disconnection according to claim 1, characterized in that: the rated voltage of the capacitors C ₁₁ and C ₁₂ is ≥ 500 kV. 7. The test method for power transformers of ultra-high voltage lines without disconnection according to claim 1, characterized in that: the resistance value of the resistor R ₁₁ is ≥ 1MΩ.

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