Auxiliary test bench for verification of cross-range three-phase high-voltage metering current transformer

Abstract

The invention relates to a cross-range three-phase high-voltage metering current transformer verification auxiliary test bench, belongs to the technical field of transformer verification, and solves the technical problems of long wiring time, single verification, low working efficiency, high labor cost, high risk and the like during verification of an existing high-voltage metering current transformer. According to the solution, the span-range three-phase high-voltage metering current transformer verification auxiliary test bench comprises a test bench body; 2-3 to-be-detected three-phase complex-ratio current transformer groups which are of the same model and are formed by one-time series connection and are pressed by a pressing assembly are placed on the lifting assembly; the primary current line comprises a non-polar end common current line, a polar end common current line and a loop gear current line; and the secondary terminal is connected with the input end of the transformation ratio online conversion intelligent control junction box of the three-phase current transformer through a secondary current line. Compared with the prior art, the device has the advantages of short wiring time, group verification, high working efficiency, low labor cost, low risk and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of transformer calibration, and particularly relates to a cross-range three-phase high-voltage metering current transformer calibration auxiliary test bench. BACKGROUND

[0002] The current transformer converts a large current into a standard small current through electromagnetic induction principle to realize safe measurement and control of the current. If not calibrated regularly, it may lead to increased measurement error, and further cause inaccurate electric energy measurement and equipment damage or system failure expansion.

[0003] The three-phase high-voltage current transformer is usually used in three-phase three-wire and three-phase four-wire circuits. The three-phase three-wire circuit uses two current transformers for A phase and C phase, and the three-phase four-wire circuit uses three current transformers for A phase, B phase and C phase. The complex ratio cross-range current transformer is a secondary multi-tap current transformer designed to realize cross-range electric energy measurement under relatively large and small loads. In the calibration process of the traditional high-voltage metering current transformer, the primary current line connection is usually fixed by bolts, which easily leads to long connection time, especially in the high-voltage environment with strict connection requirements. The traditional calibration can only calibrate a single current transformer, which is low in work efficiency and high in labor cost due to the back-and-forth moving of the current transformer during calibration. The traditional calibration requires constant power-off and re-wiring when switching the transformation ratio, which not only increases the operation steps, but also increases the personal risk of the operator. SUMMARY

[0004] In order to overcome the deficiencies of the prior art and solve the technical problems of long connection time, single calibration, low work efficiency, high labor cost and high risk in the calibration of the existing high-voltage metering current transformer, the present application provides a cross-range three-phase high-voltage metering current transformer calibration auxiliary test bench.

[0005] The present application is implemented by the following technical solutions.

[0006] The present application provides a cross-range three-phase high-voltage metering current transformer calibration auxiliary test bench, which comprises: A test bench body, which comprises a left cabinet and a right cabinet connected to each other, and a containing cavity is arranged between the left cabinet and the right cabinet; A lifting assembly arranged on one side of the test bench body where a compression assembly is installed for lifting, 3 sets of the same type of primary series-connected three-phase complex ratio current transformers to be tested are placed on the lifting assembly, the three-phase complex ratio current transformer to be tested comprises an A-phase complex ratio current transformer A-CT, a B-phase complex ratio current transformer B-CT and a C-phase complex ratio current transformer C-CT connected in series at the primary terminals; and the voltage grade of the three-phase complex ratio current transformer to be tested is 10kV~35kV; Primary current lines, the primary current lines include non-polar end common current lines, polar end common current lines and loop shelf current lines, one end of the non-polar end common current lines is connected with the non-polar end of the A-phase complex ratio current transformer A-CT, the other end of the non-polar end common current lines is connected with the non-polar end collection copper bar arranged in the inside of the test bench body; one end of the polar end common current lines is connected with the polar end of the C-phase complex ratio current transformer C-CT, the other end of the polar end common current lines is connected with the polar end collection copper bar arranged in the inside of the test bench body; the PLC program control instrument controls the solid-state relay and then controls the closing of the contactor to select the loop shelf current lines, the loop shelf current lines at least include first, second, third and fourth loop shelf current lines, the first loop shelf current line is a loop formed by passing through the polar end La threading entrance and the non-polar end Lb threading exit of the self-lift current standard current transformer, the second, third and fourth loop shelf current lines are loops formed by passing through the maximum current polar end L1 of the self-lift current standard current transformer primary tap and the non-polar ends L2, L3 and L4 of other self-lift current standard current transformer primary taps respectively; the self-lift current standard current transformer is arranged in the containing cavity for lifting current with the to-be-tested three-phase complex ratio current transformer group and serving as a standard device to detect the error of each complex ratio current transformer in the to-be-tested three-phase complex ratio current transformer group; Secondary current lines, each complex ratio current transformer in the to-be-tested three-phase complex ratio current transformer group is configured with 3 secondary current lines, each complex ratio current transformer in the to-be-tested three-phase complex ratio current transformer group is provided with a secondary terminal, the secondary terminal is connected with the input end of the three-phase current transformer ratio online conversion intelligent control terminal box through the secondary current lines, the output end of the three-phase current transformer ratio online conversion intelligent control terminal box is connected with the self-lift current standard current transformer, the main station current transformer calibrator, the current transformer secondary analog load box and the secondary switching relay group respectively, the secondary switching relay group is electrically connected between the main station control aviation plug and the main station transmission aviation plug respectively; Pressing assemblies, a plurality of pressing assemblies are arranged on the test bench body, the pressing assemblies are used for pressing the connection copper bars in series at the top of the to-be-tested three-phase complex ratio current transformer group, the pressing end head of the pressing assembly is made of insulating material.

[0007] Further, the lifting assembly is placed with the to-be-tested three-phase complex ratio current transformer group composed of 2 primary series of the same type, the to-be-tested three-phase complex ratio current transformer group includes the A-phase complex ratio current transformer A-CT and the C-phase complex ratio current transformer C-CT in series at the primary terminals.

[0008] Further, the test bench body is made of aluminum alloy or steel frame material, the test bench body top is provided with a pressing strip at both ends, and the test bench body top is provided with a reinforcing pad plate at the bottom of the pressing assembly and the side of the test bench body facing the three-phase complex ratio current transformer group to be detected.

[0009] Further, the left cabinet and the right cabinet are both provided with a partition plate, the contactor is arranged at the bottom of the partition plate, the three-phase current transformer variable ratio online conversion intelligent control terminal box is arranged on the partition plate of the right cabinet, and the solid-state relay and the secondary switching relay group are both arranged on the partition plate of the left cabinet.

[0010] Further, the lifting assembly comprises a base frame, a support table and two groups of opposite lifting units arranged between the base frame and the support table, and the base frame and the support table are both provided with U-shaped sliding grooves; the lifting unit comprises a forward and reverse toothed rod, front and rear parallel scissor lifting arms, two upper connecting rods, two lower connecting rods and a middle connecting rod in the front and rear parallel scissor lifting arms, the top and bottom of the front and rear parallel scissor lifting arms are respectively provided with the two upper connecting rods and the two lower connecting rods, the two ends of the upper connecting rod and the lower connecting rod are both provided with rolling bearings, the rolling bearings slide left and right along the U-shaped sliding grooves, the forward and reverse toothed rod penetrates the upper connecting rods of the two groups of opposite lifting units, and the two ends of the forward and reverse toothed rod are respectively provided with forward and reverse nuts; the base frame is further provided with a full-thread screw rod, and the full-thread screw rod is connected to the test bench body through a nut.

[0011] Further, in the secondary terminals of the A-phase complex ratio current transformer A-CT in the secondary current line, S1, S2 and S3 are sequentially connected to input ends ②, ③ and ④ of the three-phase current transformer variable ratio online conversion intelligent control terminal box, in the secondary terminals of the B-phase complex ratio current transformer B-CT, S1, S2 and S3 are sequentially connected to input ends ⑥, ⑦ and ⑧ of the three-phase current transformer variable ratio online conversion intelligent control terminal box, and in the secondary terminals of the C-phase complex ratio current transformer C-CT, S1, S2 and S3 are sequentially connected to input ends ⑩, ⑪ and ⑫ of the three-phase current transformer variable ratio online conversion intelligent control terminal box; output ends ②, ⑥ and ⑩ of the three-phase current transformer variable ratio online conversion intelligent control terminal box are connected in parallel to a secondary polarity end K terminal of the self-lift standard current transformer, and then connected to a K terminal of a main station transformer calibrator, output ends ③, ⑦ and ⑪ of the three-phase current transformer variable ratio online conversion intelligent control terminal box are sequentially connected to common ends of three secondary relays J1, J2 and J3 in the secondary switching relay group, the normally closed terminals of the three secondary relays J1, J2 and J3 are connected in parallel to the secondary polarity end K terminal of the self-lift standard current transformer, and the normally open terminals of the three secondary relays J1, J2 and J3 are connected in parallel to impedance terminals Z of a current transformer secondary analog load box.

[0012] Further, the solid state relays and contactors correspond one by one, the solid state relays are at least solid state relays SSR1, SSR2, SSR3 and SSR4 respectively, the contactors are at least contactors KM1, KM2, KM3 and KM4 respectively, the self-lifting current standard current transformer is provided with a primary polarity end L1, a non-polarity end L2, a non-polarity end L3, a non-polarity end L4, a polarity end La through-hole inlet and a non-polarity end Lb through-hole outlet, the contactor KM1 is provided with a 11' terminal, a 12' terminal, a 13' terminal, a 14' terminal, an A11 electromagnetic coil terminal and an A12 electromagnetic coil terminal, the contactor KM2 is provided with a 21' terminal, a 22' terminal, a 23' terminal, a 24' terminal, an A21 electromagnetic coil terminal and an A22 electromagnetic coil terminal, the contactor KM3 is provided with a 31' common terminal, a 32' terminal, a 33' terminal, a 34' terminal, an A31 electromagnetic coil terminal and an A32 electromagnetic coil terminal, and the contactor KM4 is provided with a 41' terminal, a 42' terminal, a 43' terminal, a 44' terminal, an A41 electromagnetic coil terminal and an A42 electromagnetic coil terminal; when a first loop grade current line is selected, a PLC program control instrument controls the solid state relay SSR4 to make the contactor KM4 closed, the 41' terminal is connected with the 44' terminal by penetrating into the polarity end La through-hole inlet and penetrating out of the non-polarity end Lb through-hole outlet through the first loop grade current line, the 42' terminal is connected with the polarity end busbar through the first loop grade current line, the polarity end busbar is connected with a C-phase ratio current transformer C-CT polarity end of a primary series tail end of a to-be-tested three-phase ratio current transformer group through a polarity end common current line, a A-phase ratio current transformer A-CT non-polarity end of a primary series head end of the to-be-tested three-phase ratio current transformer group is connected with a non-polarity end busbar through a non-polarity end common current line, and the non-polarity end busbar is connected with the 43' terminal through the first loop grade current line; when a second loop grade current line is selected, a PLC program control instrument controls the solid state relay SSR3 to make the contactor KM3 closed, the 31' common terminal is connected with the polarity end L1 through the second loop grade current line, the 32' terminal is connected with the polarity end busbar through the second loop grade current line, the polarity end busbar is connected with the C-phase ratio current transformer C-CT polarity end of the primary series tail end of the to-be-tested three-phase ratio current transformer group through the polarity end common current line, the A-phase ratio current transformer A-CT non-polarity end of the primary series head end of the to-be-tested three-phase ratio current transformer group is connected with the non-polarity end busbar through the non-polarity end common current line, the non-polarity end busbar is connected with the 33' terminal through the second loop grade current line, and the 34' terminal is connected with the non-polarity end L2 through the second loop grade current line.When the third circuit current line is selected, the PLC program controller controls the solid state relay SSR2 to close the contactor KM2, the 21' terminal is connected to the 31' common terminal through the third circuit current line and connected to the polarity end L1 through the second circuit current line, the 22' terminal is connected to the polarity end copper bar through the third circuit current line, the polarity end copper bar is connected to the C-phase complex ratio current transformer C-CT of the tail end of the primary series of the three-phase complex ratio current transformer group to be tested through the polarity end common current line, the non-polarity end of the A-phase complex ratio current transformer A-CT of the head end of the primary series of the three-phase complex ratio current transformer group to be tested is connected to the non-polarity end copper bar through the non-polarity end common current line, the non-polarity end copper bar is connected to the 23' terminal through the third circuit current line, and the 24' terminal is connected to the non-polarity end L3 through the third circuit current line; when the fourth circuit current line is selected, the PLC program controller controls the solid state relay SSR1 to close the contactor KM1, the A11 electromagnetic coil terminal, the A12 electromagnetic coil terminal and the solid state relay SSR1 are connected, the 11' terminal is connected to the 31' common terminal through the fourth circuit current line and connected to the polarity end L1 through the second circuit current line, the 12' terminal is connected to the polarity end copper bar through the fourth circuit current line, the polarity end copper bar is connected to the C-phase complex ratio current transformer C-CT of the tail end of the primary series of the three-phase complex ratio current transformer group to be tested through the polarity end common current line, the non-polarity end of the A-phase complex ratio current transformer A-CT of the head end of the primary series of the three-phase complex ratio current transformer group to be tested is connected to the non-polarity end copper bar through the non-polarity end common current line, the non-polarity end copper bar is connected to the 13' terminal through the fourth circuit current line, and the 14' terminal is connected to the non-polarity end L4 through the fourth circuit current line; the current capacity of the first circuit current line covers the second circuit current line, the third circuit current line and the fourth circuit current line, the current capacity of the second circuit current line covers the third circuit current line and the fourth circuit current line, and the current capacity of the third circuit current line covers the fourth circuit current line.

[0013] Further, the self-lifting flow standard current transformer and the lifting assembly bottom are provided with universal wheels with locks around.

[0014] Further, the reinforcing pad plate at the top of the test bench body is provided with a plurality of limiting waist-shaped holes, and a pressing assembly is installed at the limiting waist-shaped holes.

[0015] Further, the pressing assembly is a vertical fixed clamp.

[0016] The beneficial effects achieved by the present application are: the lifting assembly is selected, the lifting assembly can be lifted and moved to a suitable position according to the height size of the three-phase complex ratio current transformer group to be detected, and then fixed for detection test, the artificial cost is reduced, and the efficiency is improved; the compression assembly is selected, the bolt mode of traditional primary current line connection is changed, the reliability of connection is ensured, and the wiring time is also significantly reduced; the solid state relay and the contactor are selected, when the three-phase complex ratio current transformer group to be detected is detected, the solid state relay can be controlled by the PLC program control instrument to make the contactor close to select the corresponding ratio of the self-lifting standard current transformer, without manual exchange of primary line; the three-phase current transformer ratio online conversion intelligent control terminal box is selected, the ratio range of the three-phase complex ratio current transformer group to be detected can be controlled, without power-off and manual exchange of secondary line, automation is realized, and the safety risk is reduced; the present application can detect 2-3 complex ratio current transformers at a time, and the working efficiency is high.

[0017] Compared with the prior art, the present application has the advantages of short wiring time, group detection, high working efficiency, low labor cost, low risk and the like. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a structural schematic view of three complex ratio current transformers in the present application; Figure 2 is a primary current line connection structure schematic view in the present application; Figure 1 Figure 3 is a secondary current line connection structure schematic view in the present application; Figure 1 Figure 4 is a top view of the present application; Figure 1 is a rear view of the present application; Figure 5 Figure 1 is a right view of the present application Figure 6 Figure 1 Figure 7 is a circuit diagram of the primary current line in the present application; Figure 8 is a circuit diagram of the secondary current line in the present application.

[0019] ​​​​​In the diagram: 1. Test bench body; 2. Left cabinet; 3. Right cabinet; 4. Receiving cavity; 5. Lifting assembly; 6. Clamping assembly; 7. Three-phase complex ratio current transformer group under test; 8. Primary current line; 8-1. Non-polar terminal common current line; 8-2. Polar terminal common current line; 8-3. Circuit current line; 9-1. Non-polar terminal busbar; 9-2. Polar terminal busbar; 10. Solid-state relay; 11. Contactor; 12. Self-elevating standard current transformer; 13. Secondary current line; 14. Secondary terminal; 15. Intelligent control for online conversion of three-phase current transformer ratio. 16. Junction box; 17. Main station current transformer calibrator; 18. Secondary simulated load box for current transformer; 19. Secondary switching relay group; 20. Main station control aviation plug; 21. Main station transmission aviation plug; 22. Connecting copper busbar; 23. Pressure strip; 24. Reinforcing pad; 25. Partition plate; 26. Base frame; 27. Support platform; 28. U-shaped slide rail; 29. ​​Positive and negative threaded rod; 30. Scissor lift arm; 31. Upper connecting rod; 32. Lower connecting rod; 33. Middle connecting rod; 34. Rolling bearing; 35. Fully threaded screw; 36. Lockable caster wheel; 37. Limiting oblong hole. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0021] like Figures 1-8 As shown, the auxiliary test bench for calibrating a three-phase high-voltage metering current transformer with multiple measurement ranges includes: The test bench body 1 includes a left cabinet 2 and a right cabinet 3 connected to each other, and a receiving cavity 4 is provided between the left cabinet 2 and the right cabinet 3; The lifting assembly 5 is located on the side of the test bench body 1 where the clamping assembly 6 is installed, and is used for lifting. The lifting assembly 5 holds three identical three-phase complex current transformers under test connected in series. The three-phase complex current transformers under test 7 includes an A-phase complex current transformer A-CT, a B-phase complex current transformer B-CT, and a C-phase complex current transformer C-CT connected in series at their primary terminals. The voltage rating of the three-phase complex current transformers under test 7 is 10kV to 35kV. Primary current line 8, the primary current line 8 includes non-polar end common current line 8-1, polar end common current line 8-2 and loop current line 8-3, one end of the non-polar end common current line 8-1 is connected with the non-polar end of A-phase complex ratio current transformer A-CT, the other end of the non-polar end common current line 8-1 is connected with the non-polar end collection copper bar 9-1 arranged inside the test bench body 1;The polar end of the polar end common current line 8-2 is connected with the polar end of the C-phase complex ratio current transformer C-CT, and the other end of the polar end common current line 8-2 is connected with the polar end collection copper bar 9-2 arranged inside the test bench body 1;The PLC program control instrument controls the solid-state relay 10 to select the loop current line 8-3 in turn, and the solid-state relay 10 controls the closing of the contactor 11, the loop current line 8-3 at least includes first, second, third and fourth loop current lines, the first loop current line is a loop formed by passing through the polar end La threading entrance and the non-polar end Lb threading exit of the self-lift current standard current transformer 12, the second, third and fourth loop current lines are loops formed by the maximum current polar end L1 of the primary tap of the self-lift current standard current transformer 12 and the non-polar ends L2, L3 and L4 of other primary taps of the self-lift current standard current transformer 12 respectively;The self-lift current standard current transformer 12 is arranged in the containing cavity 4 for lifting current with the three-phase complex ratio current transformer group 7 to be detected and serving as a standard device to detect the error of each complex ratio current transformer in the three-phase complex ratio current transformer group 7 to be detected; Secondary current line 13, each complex ratio current transformer in the three-phase complex ratio current transformer group 7 to be detected is configured with 3 secondary current lines 13, each complex ratio current transformer in the three-phase complex ratio current transformer group 7 to be detected is provided with a secondary terminal 14, the secondary terminal 14 is connected with the three-phase current transformer ratio online conversion intelligent control terminal box 15 through the secondary current line 13, the output end of the three-phase current transformer ratio online conversion intelligent control terminal box 15 is connected with the self-lift current standard current transformer 12, the main station current transformer calibrator 16, the current transformer secondary analog load box 17 and the secondary switching relay group 18 respectively, the secondary switching relay group 18 is electrically connected between the main station control aviation plug 19 and the main station transmission aviation plug 20 respectively; Compression assembly 6, a plurality of compression assemblies 6 are arranged on the test bench body 1, the compression assembly 6 is used for compressing the connection copper bar 21 top-connected with the primary end of the three-phase complex ratio current transformer group 7 to be detected, and the compression end head of the compression assembly 6 is made of insulating material.

[0022] Specifically, the drawings show three sets of three-phase complex ratio current transformers 7 of the same type connected in series, and the loop current lines 8-3 are four groups. According to the height of the three-phase complex ratio current transformer group 7 to be tested, the three-phase complex ratio current transformer group 7 to be tested is adjusted to the appropriate height by using the lifting assembly 5, and then the primary loop is formed by using the compression assembly 6 to compress the copper bars 21, and then the secondary current lines 13 are connected according to the corresponding ratio of the three-phase complex ratio current transformer group 7 to be tested. Figure 8 After completing the secondary current lines 13 according to the national standard current transformer calibration regulation, the current transformer calibration test is performed, the labor cost is reduced, and the efficiency is improved. The lifting assembly 5 can be used to measure 10kV~35kV three-phase complex ratio current transformer group 7 to be tested, and the height of the lifting assembly 5 is adjusted to complete the test of current transformers of different voltage levels of 10kV~35kV. The setting of several compression assemblies 6 changes the traditional bolt connection compression method of the connection of the primary current lines 8, ensures the reliability of the connection, and significantly reduces the wiring and line changing time. The PLC program control instrument controls the solid-state relay 10 to control the closing of the contactor 11 to select the corresponding ratio of the loop current lines 8-3 and the self-lift standard current transformer 12, so that manual switching is not required. The three-phase current transformer ratio online conversion intelligent control terminal box 15 can control the ratio secondary switching of the three-phase complex ratio current transformer group 7 to be tested, without power off and manual wiring, realizing automation and reducing safety risks. The secondary switching relay group 18 is connected with the main station control aviation plug 19 and the main station transmission aviation plug 20, the main station controls the secondary switching relay group 18 to obtain the data of the corresponding secondary output signal of the three-phase complex ratio current transformer group 7 to be tested, and transmits the test data results to the main station through the main station transmission aviation plug 20. The test data results are detected by the electrical measuring instrument placed in the main station. The main station current transformer calibrator 16 collects the secondary output signals of the self-lift standard current transformer 12 and the three-phase complex ratio current transformer group 7 to be tested, accurately measures and calculates the vector difference signal between the two secondary signals, calculates the ratio difference and phase difference of the three-phase complex ratio current transformer group 7 to be tested, and further judges whether it is within the error limit value according to the result, so as to complete the calibration operation.

[0023] The lifting assembly 5 is placed with two sets of three-phase complex ratio current transformers 7 of the same type connected in series, and the three-phase complex ratio current transformer group 7 to be tested includes A-phase complex ratio current transformer A-CT and C-phase complex ratio current transformer C-CT connected in series at the primary terminals.

[0024] Specifically, this can complete the calibration test of two complex ratio current transformers, and also complete the calibration test of three complex ratio current transformers.

[0025] The test bench body 1 is made of aluminum alloy or steel frame material, both ends of the top of the test bench body 1 are provided with pressing strips 22, and the top of the test bench body 1 is provided with a reinforcing pad 23 on the side facing the three-phase complex current transformer group 7 to be tested.

[0026] Specifically, the aluminum alloy frame material is arranged to reduce the weight of the test bench body 1 while ensuring the structural strength of the test bench body 1 and prolonging the service life; the steel frame material is arranged to improve the strength and facilitate assembly and welding; the pressing strips 22 are arranged to further improve the shear strength of the test bench body 1; and the reinforcing pad 23 on the side of the test bench body 1 facing the three-phase complex current transformer group 7 to be tested is further provided with a rib plate, so that the test bench body 1 is uniformly stressed through the combination of the reinforcing pad 23 and the rib plate.

[0027] The left cabinet body 2 and the right cabinet body 3 are both provided with a partition plate 24, the contactor 11 is arranged at the bottom of the partition plate 24, the three-phase current transformer ratio online conversion intelligent control terminal box 15 is arranged on the partition plate 24 of the right cabinet body 3, and the solid-state relay 10 and the secondary switching relay group 18 are both arranged on the partition plate 24 of the left cabinet body 2.

[0028] Specifically, the solid-state relay 10, the contactor 11, the three-phase current transformer ratio online conversion intelligent control terminal box 15 and the secondary switching relay group 18 are arranged inside to complete the test process of switching and checking the range of the three-phase high-voltage complex current transformer ratio.

[0029] The lifting assembly 5 comprises a chassis 25, a support table 26, two groups of opposite moving lifting units arranged between the chassis 25 and the support table 26, and U-shaped sliding grooves 27 arranged on the chassis 25 and the support table 26; the lifting unit comprises a forward and reverse toothed rod 28, front and rear parallel scissor lifting arms 29, two upper connecting rods 30, two lower connecting rods 31 and a middle connecting rod 32 arranged in the middle of the front and rear parallel scissor lifting arms 29, the top and bottom of the front and rear parallel scissor lifting arms 29 are respectively provided with two upper connecting rods 30 and two lower connecting rods 31, the two ends of the upper connecting rod 30 and the lower connecting rod 31 are both provided with rolling bearings 33, the rolling bearings 33 slide back and forth along the U-shaped sliding grooves 27, the forward and reverse toothed rod 28 penetrates the upper connecting rods 30 of the two groups of opposite moving lifting units, and the two ends of the forward and reverse toothed rod 28 are respectively provided with forward and reverse nuts; the chassis 25 is further provided with a full-thread screw rod 34, and the full-thread screw rod 34 is connected to the test bench body 1 through a nut.

[0030] Specifically, the outer upper connecting rods 30 and the lower connecting rods 31 are rotatable, the rolling bearings 33 on the inner upper connecting rods 30 and the lower connecting rods 31 can slide along the U-shaped sliding grooves 27, the rotation of the positive and negative toothed rods 28 in the lifting assembly 5 drives the synchronous lifting of the two groups of opposite lifting units; the rolling bearings 33 and the U-shaped sliding grooves 27 improve the flexibility and stability of the lifting assembly 5; the full-thread screw rod 34 is connected to the test bench body 1 through the combination of the aluminum profile sliding block nut and the butterfly nut, which can reduce the influence of the lifting of the lifting unit and improve the synchronous stability of the detection process.

[0031] The S1, S2 and S3 in the secondary terminal 14 of the A-phase complex ratio current transformer A-CT in the secondary current line 13 are connected to the input ends ②, ③ and ④ of the three-phase current transformer ratio online conversion intelligent control terminal box 15 in sequence, wherein S1 represents the secondary polarity terminal of all complex ratio current transformers in the three-phase complex ratio current transformer group 7 to be detected; the S1, S2 and S3 in the secondary terminal 14 of the B-phase complex ratio current transformer B-CT are connected to the input ends ⑥, ⑦ and ⑧ of the three-phase current transformer ratio online conversion intelligent control terminal box 15 in sequence; the S1, S2 and S3 in the secondary terminal 14 of the C-phase complex ratio current transformer C-CT are connected to the input ends ⑩, ⑪ and ⑫ of the three-phase current transformer ratio online conversion intelligent control terminal box 15 in sequence; the output ends ②, ⑥ and ⑩ of the three-phase current transformer ratio online conversion intelligent control terminal box 15 are connected in parallel to the secondary polarity terminal K terminal of the self-lift standard current transformer 12, and then connected to the K terminal of the main transformer calibrator 16; the output ends ③, ⑦ and ⑪ of the three-phase current transformer ratio online conversion intelligent control terminal box 15 are connected to the common terminals of the three secondary relays J1, J2 and J3 in the secondary switching relay group 18 in sequence; the normally closed terminals of the three secondary relays J1, J2 and J3 are connected in parallel to the secondary polarity terminal K terminal of the self-lift standard current transformer 12; the normally open terminals of the three secondary relays J1, J2 and J3 are connected in parallel to the impedance terminal Z of the current transformer secondary analog load box 17. The detection test process is a process of repeatedly switching and changing the ratio range in sequence to collect difference signals and standard signals for comparison and processing.

[0032] Specifically, the three-phase current transformer ratio on-line conversion intelligent control terminal box 15 is selected, the ratio secondary switching of the three-phase complex ratio current transformer group 7 to be detected can be controlled, power-off and manual wiring are not required, automation is realized, and safety risks are reduced; the non-polarity end S2 or S3 of each current complex ratio transformer in the three-phase complex ratio current transformer group 7 to be detected is connected to the three-phase current transformer ratio on-line conversion intelligent control terminal box 15, a secondary switching relay group 18, and a secondary current line 13 and a total terminal contact resistance value sum ≤0.06Ω of each terminal input and output of a current transformer secondary analog load box 17.

[0033] The solid state relay 10 and the contactor 11 correspond one by one, the solid state relay 10 is at least solid state relay SSR1, SSR2, SSR3 and SSR4 respectively, the contactor 11 is at least contactor KM1, KM2, KM3 and KM4 respectively, the self-lift current standard current transformer 12 is provided with a primary polarity end L1, a non-polarity end L2, a non-polarity end L3, a non-polarity end L4, a polarity end La through hole entrance and a non-polarity end Lb through hole exit, the contactor KM1 is provided with 11' terminal, 12' terminal, 13' terminal, 14' terminal, A11 electromagnetic coil terminal, A12 electromagnetic coil terminal, the contactor KM2 is provided with 21' terminal, 22' terminal, 23' terminal, 24' terminal, A21 electromagnetic coil terminal, A22 electromagnetic coil terminal, the contactor KM3 is provided with 31' common terminal, 32' terminal, 33' terminal, 34' terminal, A31 electromagnetic coil terminal, A32 electromagnetic coil terminal, the contactor KM4 is provided with 41' terminal, 42' terminal, 43' terminal, 44' terminal, A41 electromagnetic coil terminal, A42 electromagnetic coil terminal, when selecting the first loop grade current line, the PLC program control instrument controls the solid state relay SSR4 to make the contactor KM4 closed, the 41' terminal is connected with the 44' terminal by the first loop grade current line from the polarity end La through hole entrance and from the non-polarity end Lb through hole exit, the 42' terminal is connected with the polarity end copper bar 9-2 through the first loop grade current line, the polarity end copper bar 9-2 is connected with the C-phase complex ratio current transformer C-CT polarity end of the primary series tail end of the three-phase complex ratio current transformer group 7 to be detected through the polarity end common current line 8-2, the A-phase complex ratio current transformer A-CT non-polarity end of the primary series head end of the three-phase complex ratio current transformer group 7 to be detected is connected with the non-polarity end copper bar 9-1 through the non-polarity end common current line 8-1, the non-polarity end copper bar 9-1 is connected with the 43' terminal through the first loop grade current line, when selecting the second loop grade current line, the PLC program control instrument controls the solid state relay SSR3 to make the contactor KM3 closed, the 31' common terminal is connected with the polarity end L1 through the second loop grade current line, the 32' terminal is connected with the polarity end copper bar 9-2 through the second loop grade current line, the polarity end copper bar 9-2 is connected with the C-phase complex ratio current transformer C-CT polarity end of the primary series tail end of the three-phase complex ratio current transformer group 7 to be detected through the polarity end common current line 8-2, the A-phase complex ratio current transformer A-CT non-polarity end of the primary series head end of the three-phase complex ratio current transformer group 7 to be detected is connected with the non-polarity end copper bar 9-1 through the non-polarity end common current line 8-1, the non-polarity end copper bar 9-1 is connected with the 33' terminal through the second loop grade current line, the 34' terminal is connected with the non-polarity end L2 through the second loop grade current line.When the third circuit current line is selected, the PLC program controller controls the solid state relay SSR2 to make the contactor KM2 closed, the 21' terminal is connected with the 31' common terminal through the third circuit current line and connected with the polarity end L1 through the second circuit current line, the 22' terminal is connected with the polarity end copper bar 9-2 through the third circuit current line, the polarity end copper bar 9-2 is connected with the C-phase complex ratio current transformer C-CT of the primary series tail end of the three-phase complex ratio current transformer group 7 to be tested through the polarity end common current line 8-2, the non-polarity end of the A-phase complex ratio current transformer A-CT of the primary series head end of the three-phase complex ratio current transformer group 7 to be tested is connected with the non-polarity end copper bar 9-1 through the non-polarity end common current line 8-1, the non-polarity end copper bar 9-1 is connected with the 23' terminal through the third circuit current line, and the 24' terminal is connected with the non-polarity end L3 through the third circuit current line; when the fourth circuit current line is selected, the PLC program controller controls the solid state relay SSR1 to make the contactor KM1 closed, the A11 electromagnetic coil terminal, the A12 electromagnetic coil terminal and the solid state relay SSR1 are connected, the 11' terminal is connected with the 31' common terminal through the fourth circuit current line and connected with the polarity end L1 through the second circuit current line, the 12' terminal is connected with the polarity end copper bar 9-2 through the fourth circuit current line, the polarity end copper bar 9-2 is connected with the C-phase complex ratio current transformer C-CT of the primary series tail end of the three-phase complex ratio current transformer group 7 to be tested through the polarity end common current line 8-2, the non-polarity end of the A-phase complex ratio current transformer A-CT of the primary series head end of the three-phase complex ratio current transformer group 7 to be tested is connected with the non-polarity end copper bar 9-1 through the non-polarity end common current line 8-1, the non-polarity end copper bar 9-1 is connected with the 13' terminal through the fourth circuit current line, and the 14' terminal is connected with the non-polarity end L4 through the fourth circuit current line; the current capacity of the first circuit current line covers the second circuit current line, the third circuit current line and the fourth circuit current line, the current capacity of the second circuit current line covers the third circuit current line and the fourth circuit current line, and the current capacity of the third circuit current line covers the fourth circuit current line.

[0034] Table 1: Self-lift standard current transformer ratio table Specifically, the general standard current transformer is usually selected to have a cross-core and multiple turns because the precision cannot be reached, and in the present application, the self-lift standard current transformer 12 is designed to have a cross-core and one turn, and the optimal scheme is selected. When the first circuit current line is selected, the PLC program controller controls the solid state relay SSR4 to make the contactor KM4 closed, the secondary positions of the self-lift standard current transformer 12 are respectively selected as K1, K2, K3, K4, K5, K6, K7, K8, K9, K 10 , K 11 and K12 When the first circuit current line is selected, the primary current selection of the first circuit current line is 2400A, corresponding to 400A, 500A, 600A, 630A, 750A, 800A, 1000A, 1200A, 1250A, 1500A, 1600A and 2000A respectively; when the second circuit current line is selected, the PLC program controller controls the solid-state relay SSR3 to close the contactor KM3, and the secondary selection of the standard current transformer 12 is K1, K2, K3, K5, K6, K7, K8, K9, K 10 and K 11 When the first circuit current line is selected, the primary current selection of the first circuit current line is 2400A, corresponding to 400A, 500A, 600A, 630A, 750A, 800A, 1000A, 1200A, 1250A, 1500A, 1600A and 2000A respectively; when the second circuit current line is selected, the PLC program controller controls the solid-state relay SSR3 to close the contactor KM3, and the secondary selection of the standard current transformer 12 is K1, K2, K3, K5, K6, K7, K8, K9, K 10 When the first circuit current line is selected, the primary current selection of the first circuit current line is 2400A, corresponding to 400A, 500A, 600A, 630A, 750A, 800A, 1000A, 1200A, 1250A, 1500A, 1600A and 2000A respectively; when the second circuit current line is selected, the PLC program controller controls the solid-state relay SSR3 to close the contactor KM3, and the secondary selection of the standard current transformer 12 is K1, K2, K3, K5, K6, K7, K8, K9, K 10 and K 12 When the first circuit current line is selected, the primary current selection of the first circuit current line is 2400A, corresponding to 400A, 500A, 600A, 630A, 750A, 800A, 1000A, 1200A, 1250A, 1500A, 1600A and 2000A respectively; when the second circuit current line is selected, the PLC program controller controls the solid-state relay SSR3 to close the contactor KM3, and the secondary selection of the standard current transformer 12 is K1, K2, K3, K5, K6, K7, K8, K9, K

[0035] The self-lifting standard current transformer 12 and the lifting assembly 5 are provided with a locking universal wheel 35 around the bottom.

[0036] Specifically, the locking universal wheel 35 is provided to enable the self-lifting standard current transformer 12 and the lifting assembly 5 to move freely, reducing the labor cost of moving the to-be-inspected three-phase complex current transformer set 7 and the self-lifting standard current transformer 12 back and forth, and improving the efficiency.

[0037] The reinforcing pad plate 23 on the top of the test bench body 1 is provided with a plurality of limiting waist-shaped holes 36, and the pressing assembly 6 is installed at the limiting waist-shaped holes 36.

[0038] Specifically, the limiting waist-shaped holes 36 are arranged so that the pressing assembly 6 can be positioned according to the length size and the primary terminal orientation of the to-be-tested three-phase complex ratio current transformer set 7, facilitating the position adjustment of the pressing assembly 6 and facilitating the satisfaction of different wiring sizes of the to-be-tested three-phase complex ratio current transformer set 7, and improving the practicability.

[0039] The pressing assembly 6 is a vertical fixed clamp.

[0040] Specifically, the vertical fixed clamp is designed with ergonomics, comfortable grip and convenient operation, and the vertical fixed clamp can be locked and generate a large clamping force, so as to ensure that the clamped parts will not be loosened.

[0041] The working process of the present application is as follows: According to the length size of the to-be-tested three-phase complex ratio current transformer set 7, the position of the pressing assembly 6 is determined, the to-be-tested three-phase complex ratio current transformer set 7 is placed on the support table 26 of the lifting assembly 5, attention is paid to the direction of the primary current line 8, the connecting copper bar 21 is placed on the top of the primary terminal of the to-be-tested three-phase complex ratio current transformer set 7, the pressing assembly 6 is used to press the connecting copper bar 21 on the primary terminal of the to-be-tested three-phase complex ratio current transformer set 7, one end of the non-polar end common current line 8-1 is connected with the non-polar end of the A-phase complex ratio current transformer A-CT, and the other end of the non-polar end common current line 8-1 is connected with the non-polar end bus copper bar 9-1; one end of the polar end common current line 8-2 is connected with the polar end of the C-phase complex ratio current transformer C-CT, and the other end of the polar end common current line 8-2 is connected with the polar end bus copper bar 9-2; according to the transformation ratio parameters of the to-be-tested three-phase complex ratio current transformer set 7, the PLC program control instrument controls the solid-state relay 10 to make the contactor 11 closed so as to select the loop current line 8-3. The secondary switching relay set 18 is connected with the main station control aviation plug 19 and the main station transmission aviation plug 20, the main station obtains the data of the corresponding secondary output signal of the to-be-tested three-phase complex ratio current transformer set 7 by controlling the secondary switching relay set 18, transmits the test data result to the main station through the main station transmission aviation plug 20, and detects by the electrical measuring equipment placed in the main station. The main station transformer calibrator 16 collects the secondary output difference signals and standard signals of the self-rising standard current transformer 12 and the to-be-tested three-phase complex ratio current transformer set 7, accurately calculates and compares the vector difference between the two secondary signals, calculates the ratio difference and phase difference of the to-be-tested three-phase complex ratio current transformer set 7, and further judges whether it is within the error limit value range according to the result, so as to complete the calibration operation.

[0042] The embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, and can be changed within the knowledge of those skilled in the art, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the present application.

Claims

1. An auxiliary test bench for calibrating three-phase high-voltage metering current transformers across different ranges, characterized in that: include: The test bench body (1) includes a left cabinet (2) and a right cabinet (3) connected to each other, and a receiving cavity (4) is provided between the left cabinet (2) and the right cabinet (3). The lifting assembly (5) is located on the side of the test bench body (1) where the clamping assembly (6) is installed for lifting. The lifting assembly (5) is equipped with three identical three-phase complex current transformers connected in series at the primary terminals. The three-phase complex current transformers (7) are equipped with an A-phase complex current transformer A-CT, a B-phase complex current transformer B-CT, and a C-phase complex current transformer C-CT connected in series at the primary terminals. The voltage rating of the three-phase complex current transformers (7) is 10kV~35kV. The primary current line (8) includes a non-polar common current line (8-1), a polar common current line (8-2), and a loop current line (8-3). One end of the non-polar common current line (8-1) is connected to the non-polar terminal of the A-phase complex current transformer A-CT, and the other end of the non-polar common current line (8-1) is connected to the non-polar copper busbar (9-1) located inside the test bench body (1). One end of the polar common current line (8-2) is connected to the polar terminal of the C-phase complex current transformer C-CT, and the other end of the polar common current line (8-2) is connected to the polar copper busbar (9-2) located inside the test bench body (1). The PLC programmable controller controls the solid-state relay (10) and then controls the closing of the contactor (11) to select the loop. The current line (8-3) includes at least a first, second, third and fourth loop current line. The first loop current line is formed by a single turn through the polarity terminal La of the self-rising current standard current transformer (12) at the inlet and the non-polarity terminal Lb at the outlet. The second, third and fourth loop current lines are formed by the maximum current polarity terminal L1 of the primary tap of the self-rising current standard current transformer (12) and the non-polarity terminals L2, L3 and L4 of the other primary taps of the self-rising current standard current transformer (12) respectively. The self-rising current standard current transformer (12) is located in the housing cavity (4) and is used to raise the current together with the three-phase complex current transformer group (7) under test and to serve as a standard to detect the error of each complex current transformer in the three-phase complex current transformer group (7) under test. Secondary current lines (13): Each complex current transformer in the three-phase complex current transformer group (7) under test is equipped with 3 secondary current lines (13). Each complex current transformer in the three-phase complex current transformer group (7) under test is provided with secondary terminals (14). The secondary terminals (14) are connected to the input terminal of the intelligent control junction box (15) for online conversion of the three-phase current transformer ratio through the secondary current lines (13). The output terminal of the intelligent control junction box (15) for online conversion of the three-phase current transformer ratio is connected to the self-rising current standard current transformer (12), the main station current transformer calibrator (16), the current transformer secondary simulation load box (17), and the secondary switching relay group (18) respectively. The secondary switching relay group (18) is electrically connected to the main station control aviation plug (19) and the main station transmission aviation plug (20) respectively. A clamping assembly (6) is provided on the test bench body (1). The clamping assembly (6) is used to clamp the connecting copper busbar (21) connected in series at the top primary end of the three-phase complex current transformer group (7) under test. The clamping end of the clamping assembly (6) is made of insulating material.

2. The auxiliary test bench for calibrating a three-phase high-voltage metering current transformer across ranges as described in claim 1, characterized in that: The lifting assembly (5) is equipped with two identical three-phase complex current transformers connected in series at the primary terminals (7). The three-phase complex current transformers (7) include an A-phase complex current transformer A-CT and a C-phase complex current transformer C-CT connected in series at the primary terminals.

3. The auxiliary test bench for calibrating a three-phase high-voltage metering current transformer across ranges as described in claim 1, characterized in that: The test bench body (1) is made of aluminum alloy or steel frame material. Pressure strips (22) are provided at both ends of the top of the test bench body (1). Reinforcing pads (23) are provided on the top of the test bench body (1) at the bottom of the clamping assembly (6) and on the side of the test bench body (1) facing the three-phase complex current transformer group (7) to be tested.

4. The auxiliary test bench for calibrating a three-phase high-voltage metering current transformer across ranges as described in claim 1, characterized in that: The left cabinet (2) and the right cabinet (3) are both equipped with partitions (24). The contactor (11) is located at the bottom of the partition (24). The intelligent control junction box (15) for online conversion of the three-phase current transformer ratio is located on the partition (24) of the right cabinet (3). The solid-state relay (10) and the secondary switching relay group (18) are both located on the partition (24) of the left cabinet (2).

5. The auxiliary test bench for calibrating a three-phase high-voltage metering current transformer across ranges as described in claim 1, characterized in that: The lifting assembly (5) includes a base frame (25), a support platform (26), and two sets of opposing lifting units located between the base frame (25) and the support platform (26). Both the base frame (25) and the support platform (26) are provided with U-shaped grooves (27). The lifting unit includes a positive and negative threaded rod (28), a scissor-type lifting arm (29) that is parallel to the front and back, two upper connecting rods (30), two lower connecting rods (31), and a middle connecting rod (32) in the middle of the scissor-type lifting arm (29) that is parallel to the front and back. The top and bottom of the scissor-type lifting arm (29) are also connected. Two upper connecting rods (30) and two lower connecting rods (31) are provided respectively. Rolling bearings (33) are provided at both ends of the upper connecting rods (30) and the lower connecting rods (31). The rolling bearings (33) slide back and forth along the U-shaped slide groove (27). The positive and negative threaded rods (28) pass through the upper connecting rods (30) of the two sets of lifting units moving in opposite directions. Positive and negative nuts are provided at both ends of the positive and negative threaded rods (28). A fully threaded screw (34) is also provided on the base frame (25). The fully threaded screw (34) is connected to the test bench body (1) through nuts.

6. The auxiliary test bench for calibrating a three-phase high-voltage metering current transformer across ranges as described in claim 1, characterized in that: In the secondary current line (13), the secondary terminals (14) of the A-phase complex ratio current transformer A-CT are connected in sequence to the input terminals ②, ③, and ④ of the intelligent control junction box (15) for online conversion of the three-phase current transformer ratio. The secondary terminals (14) of the B-phase complex ratio current transformer B-CT are connected in sequence to the input terminals ⑥, ⑦, and ⑧ of the intelligent control junction box (15) for online conversion of the three-phase current transformer ratio. The secondary terminals (14) of the C-phase complex ratio current transformer C-CT are connected in sequence to the input terminals ⑩, ⑪, and ⑫ of the intelligent control junction box (15) for online conversion of the three-phase current transformer ratio. The output terminals ②, ⑥, and ⑩ of the control junction box (15) are connected in parallel to the secondary polarity terminal K of the self-rising current standard current transformer (12) and then connected to the K terminal of the main transformer calibrator (16). The output terminals ③, ⑦, and ⑪ of the three-phase current transformer ratio online conversion intelligent control junction box (15) are connected in sequence to the common terminal of the three secondary relays J1, J2, and J3 in the secondary switching relay group (18). The normally closed terminals of the three secondary relays J1, J2, and J3 are connected in parallel to the secondary polarity terminal K of the self-rising current standard current transformer (12). The normally open terminals of the three secondary relays J1, J2, and J3 are connected in parallel to the impedance terminal Z of the secondary analog load box (17) of the current transformer.

7. The auxiliary test bench for calibrating a three-phase high-voltage metering current transformer across ranges as described in claim 1, characterized in that: The solid-state relays (10) and contactors (11) correspond one-to-one. The solid-state relays (10) are at least SSR1, SSR2, SSR3 and SSR4, and the contactors (11) are at least KM1, KM2, KM3 and KM4. The self-rising current standard current transformer (12) is provided with a primary polarity terminal L1, a non-polarity terminal L2, a non-polarity terminal L3, a non-polarity terminal L4, a polarity terminal La through-hole inlet and a non-polarity terminal Lb through-hole outlet. The contactors K Contactor M1 has terminals 11', 12', 13', 14', A11 (electromagnetic coil terminal), and A12 (electromagnetic coil terminal). Contactor KM2 has terminals 21', 22', 23', 24', A21 (electromagnetic coil terminal), and A22 (electromagnetic coil terminal). Contactor KM3 has terminals 31' (common terminal), 32', 33', 34', A31 (electromagnetic coil terminal), and A32 (electromagnetic coil terminal). Contactor KM4 has terminals 41'... Terminals 41, 42, 43, 44, A41 (electromagnetic coil terminal), and A42 (electromagnetic coil terminal); when the first circuit current line is selected, the PLC controller controls the solid-state relay SSR4 to close the contactor KM4. Terminal 41' enters through the polarity terminal La through-hole and exits through the non-polarity terminal Lb through-hole via the first circuit current line, connecting to terminal 44'. Terminal 42' is connected to the polarity terminal busbar (9-2) via the first circuit current line. The copper busbar (9-2) is connected to the polarity terminal of the C-CT of the three-phase complex current transformer group (7) under test via the polarity terminal common current line (8-2). The non-polarity terminal of the A-CT of the three-phase complex current transformer group (7) under test is connected to the non-polarity terminal busbar (9-1) via the non-polarity terminal common current line (8-1). The non-polarity terminal busbar (9-1) is connected to the 43' terminal via the first circuit current line.When the second circuit current line is selected, the PLC controller controls the solid-state relay SSR3 to close the contactor KM3. The 31' common terminal is connected to the polarity terminal L1 through the second circuit current line, and the 32' terminal is connected to the polarity terminal busbar (9-2) through the second circuit current line. The polarity terminal busbar (9-2) is connected to the polarity terminal of the C-phase complex current transformer C-CT at the end of the primary series connection of the three-phase complex current transformer group (7) under test through the polarity terminal common current line (8-2). The non-polarity terminal of the A-phase complex current transformer A-CT at the beginning of the primary series connection of the three-phase complex current transformer group (7) under test is connected to the non-polarity terminal busbar (9-1) through the non-polarity terminal common current line (8-1). The non-polar terminal busbar (9-1) is connected to terminal 33' via the second circuit current line, and terminal 34' is connected to the non-polar terminal L2 via the second circuit current line. When the third circuit current line is selected, the PLC controller controls the solid-state relay SSR2 to close contactor KM2. Terminal 21' is connected to the 31' common terminal via the third circuit current line and connected to the polar terminal L1 via the second circuit current line. Terminal 22' is connected to the polar terminal busbar (9-2) via the third circuit current line. The polar terminal busbar (9-2) is connected to the polar terminal of the C-phase complex current transformer C-CT at the end of the primary series connection of the three-phase complex current transformer group (7) under test via the polar terminal common current line (8-2). The non-polar terminal of the A-phase complex current transformer A-CT at the first series end of the three-phase complex current transformer group (7) under test is connected to the non-polar terminal busbar (9-1) through the non-polar terminal common current line (8-1). The non-polar terminal busbar (9-1) is connected to terminal 23' through the third loop current line. Terminal 24' is connected to the non-polar terminal L3 through the third loop current line. When the fourth loop current line is selected, the PLC controller controls the solid-state relay SSR1 to close the contactor KM1. The A11 electromagnetic coil terminal, the A12 electromagnetic coil terminal and the solid-state relay SSR1 are connected. Terminal 11' is connected to the 31' common terminal through the fourth loop current line and utilizes the second loop current line. The 12' terminal is connected to the polarity terminal L1. The polarity terminal busbar (9-2) is connected to the polarity terminal busbar (9-2) through the fourth circuit current line. The polarity terminal busbar (9-2) is connected to the polarity terminal of the C-phase complex current transformer C-CT at the end of the primary series connection of the three-phase complex current transformer group (7) under test through the polarity terminal common current line (8-2). The non-polarity terminal of the A-phase complex current transformer A-CT at the beginning of the primary series connection of the three-phase complex current transformer group (7) under test is connected to the non-polarity terminal busbar (9-1) through the non-polarity terminal common current line (8-1). The non-polarity terminal busbar (9-1) is connected to the 13' terminal through the fourth circuit current line. The 14' terminal is connected to the non-polarity terminal L4 through the fourth circuit current line.The current capacity of the first circuit current line covers the current capacity of the second, third, and fourth circuit current lines; the current capacity of the second circuit current line covers the current capacity of the third and fourth circuit current lines; and the current capacity of the third circuit current line covers the current capacity of the fourth circuit current line.

8. The auxiliary test bench for calibrating a three-phase high-voltage metering current transformer across ranges as described in claim 1, characterized in that: The self-elevating standard current transformer (12) and the lifting assembly (5) are equipped with lockable casters (35) around their bottom.

9. The auxiliary test bench for calibrating a three-phase high-voltage metering current transformer across ranges as described in claim 3, characterized in that: The test bench body (1) has a number of limiting waist-shaped holes (36) on the top reinforcing pad (23), and a clamping component (6) is installed at the limiting waist-shaped hole (36).

10. The auxiliary test bench for calibrating a three-phase high-voltage metering current transformer across ranges according to claim 1, characterized in that: The clamping assembly (6) is a vertically fixed clamp.

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