Detection device for secondary circuit of current transformer of high-voltage switch cabinet

Abstract

The utility model relates to a high-voltage switch cabinet current transformer secondary circuit detection device and method, and the device comprises a current transformer, a comprehensive protector, an AC ammeter, a mutual inductor comprehensive tester, and a clamp meter, a leading-out terminal is connected with a leading-out terminal, a leading-in terminal is connected with a leading-in terminal, and a leading-out terminal is connected with a leading-out terminal. A series circuit of primary side windings of the current transformers of all phases is formed, and the wire inlet end of one current transformer and the wire outlet end of the other current transformer at the two ends of the series circuit are connected to the current wire outlet end of the transformer comprehensive tester. A secondary side winding of each phase of current transformer of the high-voltage switch cabinet is connected in series with the ampere meter and the comprehensive protector to form a current transformer secondary circuit; according to the utility model, whether the secondary circuit of the current transformer is correctly wired can be visually and accurately detected, and the safe operation of the high-voltage switch cabinet is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of power systems, and in particular to a device and method for detecting a secondary circuit of a current transformer in a high-voltage switch cabinet. Background Art

[0002] The current transformer (hereinafter referred to as CT) in the substation equipment is the main equipment for measuring, metering and providing sampling signals for protection, so the reliability of operation is very important. If the secondary winding of the CT in operation is open-circuited, a very high voltage will be induced on the secondary coil, which will seriously threaten the safety of personnel and equipment. Protections such as differential protection and zero-sequence protection may malfunction due to the unbalanced current generated when the circuit is open; the secondary circuit of the current transformer in the high-voltage switch cabinet directly affects whether the equipment can operate safely and whether the measurement is accurate. If the secondary protection circuit of the transformer is wrong, it will directly lead to malfunction of the switch or refusal to operate the switch in a fault state. In either case, it will cause huge losses, so the correctness of the secondary circuit of the current transformer is of great significance.

[0003] In the current transformer unit test, not only the transformer ratio should be tested, but also the polarity of the transformer and the integrity of the circuit should be fully tested to ensure that the current circuit connected to the integrated protector and meter is correct and the polarity meets the protection and measurement requirements. In the existing high-voltage switchgear current transformer group test, a single-phase current transformer is used to detect the secondary circuit. Figure 1 In the current transformer measurement test, a large current is usually applied to the primary side of each current transformer, and the value and phase of the secondary current are measured on the secondary side to determine whether the current transformer and the secondary circuit instrument wiring are correct. Because only one phase can be applied with current at a time, this scheme may result in misjudgment and cannot completely and accurately check the wiring of the secondary current circuit. This is not allowed for the protection and measurement of the high-voltage switchgear, and affects the normal operation of the equipment. Summary of the invention

[0004] The utility model provides a high-voltage switch cabinet current transformer secondary circuit detection device, which can intuitively and accurately detect whether the current transformer secondary circuit is correctly connected, thereby ensuring the safe operation of the high-voltage switch cabinet.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A high-voltage switch cabinet current transformer secondary circuit detection device comprises a current transformer, a comprehensive protector, an AC ammeter, a transformer comprehensive tester, and a clamp meter. The outgoing line ends of the primary windings of the current transformers arranged in each phase of the high-voltage switch cabinet are connected to the outgoing line ends, and the incoming line ends are connected to the incoming line ends, so as to form a series circuit of the primary windings of the current transformers of each phase. The remaining one current transformer incoming line end and the other current transformer outgoing line end at both ends of the series circuit are connected to the current outgoing line end of the transformer comprehensive tester. The secondary windings of the current transformers of each phase of the high-voltage switch cabinet are connected in series with the ammeter and the comprehensive protector to form a current transformer secondary circuit.

[0007] Furthermore, an ammeter is connected in series to the measuring winding in the secondary side winding of the current transformer in the secondary circuit of the current transformer, the protection winding in the secondary side winding of the current transformer in the secondary circuit of the current transformer is connected to the integrated protector, the output end of the ammeter is connected to the integrated protector, the grounding ends of the current transformer and the integrated protector are grounded, and the clamp meter is arranged on the grounding wire.

[0008] Furthermore, the current transformers provided at each phase of the high-voltage switch cabinet have the same transformation ratio.

[0009] Furthermore, the series circuit of the primary winding of each phase current transformer adopts a 50-150mm 2 Use soft copper wire to connect.

[0010] Compared with the prior art, the beneficial effects of the utility model are:

[0011] 1) By connecting the outgoing line end and the incoming line end of the primary winding of the current transformer set in each phase of the high-voltage switch cabinet, the polarity of the current transformer and the integrity of the secondary circuit can be detected intuitively and accurately;

[0012] 2) Resolve the risk of misjudgment and ensure the safe operation of high-voltage switchgear. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a wiring diagram of the primary winding of the single-phase current transformer for large current detection described in the utility model.

[0014] Figure 2 It is a wiring diagram of the primary winding of the three-phase current transformer described in the embodiment of the utility model. Figure 3 It is a schematic diagram of the secondary circuit connection of the three-phase current transformer described in the embodiment of the utility model.

[0015] Figure 4 It is a schematic diagram of the same-name terminals of the three-phase current transformer described in the embodiment of the utility model. Figure 5 It is the secondary circuit current phasor diagram after the three-phase current transformers described in the embodiment of the utility model are connected in series. DETAILED DESCRIPTION

[0016] The specific implementation of the utility model is further described below in conjunction with the accompanying drawings:

[0017] See Figure 2 , is a wiring diagram of the primary winding of the three-phase current transformer of the utility model. The utility model is a detection device for the secondary circuit of the current transformer of a high-voltage switch cabinet, comprising a current transformer, a comprehensive protector, an AC ammeter, a transformer comprehensive tester, and a clamp meter. The three phases of the high-voltage switch cabinet are all provided with current transformers, the output terminal of the A-phase current transformer is connected to the output terminal of the B-phase current transformer, the input terminal of the B-phase current transformer is connected to the input terminal of the C-phase current transformer, and the input terminal of the A-phase current transformer and the output terminal of the C-phase current transformer are connected to the current output terminal of the transformer comprehensive tester.

[0018] See Figure 3 The measuring windings A411, B411, and C411 in the secondary windings of the current transformers in the secondary circuits of the current transformers of each phase of the high-voltage switch cabinet are connected in series with ammeters, and the protection windings A421, B421, and C421 in the secondary windings of the current transformers in the secondary circuits of the current transformers of each phase are connected to the integrated protector. The output end of the ammeter is connected to the integrated protector, the grounding ends of the current transformers and the integrated protector are grounded, and the clamp meter is set on the grounding wire.

[0019] See Figure 4 , use 50~150mm between the P2 end of A mutual inductor and the P2 end of B mutual inductor 2 Connect the soft copper wire of the transformer to the transformer tester. Connect the P1 end of the B transformer to the P1 end of the C transformer. Then connect the P1 end of the A transformer and the P2 end of the C transformer to the transformer tester.

[0020] See Figure 5 ,according to Figure 4 The wiring method is used to draw the current vector diagram of the primary and secondary sides of the mutual inductor, and the phase relationship between the primary and secondary sides of each mutual inductor can be seen.

[0021] Working principle: Connect the A-phase current transformer outlet of the current transformer set in each phase of the high-voltage switch cabinet to the B-phase current transformer outlet, and connect the B-phase current transformer inlet to the C-phase current transformer inlet, forming a series circuit of the primary winding of each phase current transformer. The A-phase current transformer inlet and the C-phase current transformer outlet are connected to the current outlet of the transformer comprehensive tester. After the transformer comprehensive tester provides a stable primary current, enter the comprehensive protector to check whether the current transformer measurement current and protection current are consistent with the current after the current transformer ratio, and check whether the secondary sides of the adjacent phase current transformers of the comprehensive protector meet the phase angle difference of 180 degrees, and the phase angle of the secondary sides of the alternate phase current transformers is the same.

[0022] like Figure 5 As shown, because the current transformers P1 and 1S1 are the same terminals, according to the primary series relationship of the transformers, the three-phase current amplitudes are equal, so the primary side A phase and C phase current Same phase, A phase and B phase current Reverse phase, so check the secondary current through the integrated protector The phase meets the above rules. Taking 200 / 5 transformer as an example, when the transformer comprehensive tester outputs 40A current through the transformer primary, the current values ​​of N411 and N421 are 1A at the same time. Otherwise, it means that the secondary wiring of the current transformer is incorrect, thus judging that the secondary side circuit of the current transformer of the high-voltage switch cabinet is correctly connected.

[0023] The above embodiments are implemented based on the technical solution of the utility model, and detailed implementation methods and specific operation processes are given, but the protection scope of the utility model is not limited to the above embodiments. The methods used in the above embodiments are conventional methods unless otherwise specified.

Claims

1. A high-voltage switch cabinet current transformer secondary circuit detection device, characterized in that: It includes a current transformer, a comprehensive protector, an AC ammeter, a transformer comprehensive tester, and a clamp meter. The outgoing line ends of the primary windings of the current transformers arranged in each phase of the high-voltage switch cabinet are connected to the outgoing line ends, and the incoming line ends are connected to the incoming line ends, forming a series circuit of the primary windings of the current transformers of each phase. The remaining one current transformer incoming line end and the other current transformer outgoing line end at both ends of the series circuit are connected to the current outgoing line end of the transformer comprehensive tester. The secondary windings of the current transformers of each phase of the high-voltage switch cabinet are connected in series with the ammeter and the comprehensive protector to form a current transformer secondary circuit.

2. A high-voltage switch cabinet current transformer secondary circuit detection device according to claim 1, characterized in that: An ammeter is connected in series to the measuring winding in the secondary winding of the current transformer in the secondary circuit of the current transformer, a protection winding in the secondary winding of the current transformer in the secondary circuit of the current transformer is connected to a comprehensive protector, an output end of the ammeter is connected to the comprehensive protector, the grounding ends of the current transformer and the comprehensive protector are grounded, and the clamp meter is arranged on the grounding wire.

3. A high-voltage switch cabinet current transformer secondary circuit detection device according to claim 1, characterized in that: The current transformers arranged at each phase of the high-voltage switch cabinet have the same transformation ratio.

4. A high-voltage switch cabinet current transformer secondary circuit detection device according to claim 1, characterized in that: The series circuit of the primary winding of each phase current transformer adopts 50-150mm 2 Use soft copper wire to connect.

Images