Current transformer transformation ratio switching auxiliary device

Abstract

The utility model discloses a transformation ratio switching auxiliary device of a current transformer. The device is connected in series between the current transformer and an instrument. The device comprises a neutral point circuit of which one end is connected with a current transformer neutral point terminal and the other end is connected with an instrument; one end of each phase change circuit is electrically connected with one phase of the current transformer, the other end of each phase change circuit is electrically connected with one end of an output circuit, and the other end of each output circuit is connected with an instrument; one end of the transformation ratio switching plugboard is electrically connected with the output circuit, and the other end of the transformation ratio switching plugboard is electrically connected with one transformation ratio of the phase change circuit; and when the transformation ratio is switched, the short circuit plugboard is electrically connected with the same transformation ratio of each phase change circuit and the neutral point circuit at the same time, so that the secondary side of the current transformer is ensured not to be open-circuited. According to the utility model, the secondary side open circuit in the transformation ratio switching process can be effectively prevented, and the safety of the system is improved; the transformation ratio switching operation is simplified, and the workload and the error possibility of operators are reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of current transformers, and particularly relates to an auxiliary device for ratio conversion of current transformers. Background Technique

[0002] A current transformer is a device that measures by converting a large primary current into a small secondary current based on the principle of electromagnetic induction, and it is widely used in the power system.

[0003] Since the construction of power infrastructure is planned according to the long-term scale, the power loads in the future and at present have different requirements for the capacities of power equipment at different stages. For example, Figure 1 As shown, it is a line interval of the power system. The three-phase current planned for this period is 1,600 A, and the long-term requirement is 2,000 A. The part enclosed by the dotted line is a three-phase double-ratio current transformer. To meet the measurement and control accuracy, with different power line loads, the rated current parameters of the current transformer also need to change accordingly. Multi-ratio current transformers have been widely used in the power system.

[0004] Due to the possible differences in the recent and long-term power loads of the power system, multi-ratio current transformers are widely used. For example: 1S1-1S3 2000 / 1; 1S1-1S2 1600 / 1; when the power load is large, the large ratio 2000 / 1 is adopted, and when the power load is low, the small ratio 1600 / 1 is adopted. Selecting the ratio according to actual needs can increase the accuracy of the current collected by the current transformer.

[0005] For example, Figure 2 As shown, on the left is a three-phase multi-ratio current transformer, which is connected to the instrument on the right through a cable. Its function is to collect the primary current in the power system, convert the large system current into a small current according to a ratio and collect it into an ammeter or a relay protection device for monitoring the system operation status and protecting the system safety.

[0006] When the current transformer is in live operation, it is not allowed to open the secondary side. Opening the secondary side will generate extremely high voltage, threatening the safety of staff and secondary equipment. At present, the traditional wiring method is to fixedly select a ratio for wiring. When the ratio needs to be switched, the whole station or this interval needs to be powered off. Power outage of important users will affect safe production and reduce the power supply reliability of the power system. Power outage of the substation requires opening a work permit and performing a series of complex switching operations, consuming a lot of time. It is necessary for the construction unit to go to the site to modify the terminal block wiring to adjust the ratio. After the loop inspection is safe, power can be restored.

[0007] The traditional method has the following disadvantages:

[0008] 1. Switching the ratio requires complex wiring modification work, and operation errors may bring potential power supply hazards.

[0009] 2. Changing the transformation ratio requires power outage of the substation, which affects the normal production of power users and reduces the power supply reliability of the power system.

[0010] 3. Restoring power supply takes time. Power outage and power restoration require operation tickets, and the processes such as switching operations are cumbersome.

[0011] 4. Modifying the wiring construction work requires multiple people to complete.

[0012] 5. If the secondary cable is not long enough, the secondary cable needs to be re-laid. Summary of the Utility Model

[0013] Aiming at the problems existing in the background technology, the purpose of the utility model is to provide an auxiliary device for current transformer transformation ratio switching with simple operation, no need to modify the wiring, no need to cut off power, and high safety.

[0014] To achieve the above purpose, the auxiliary device for current transformer transformation ratio switching designed by the utility model is characterized in that: the device is connected in series between the current transformer and the instrument; the device includes:

[0015] A neutral point circuit, one end of which is connected to the neutral point terminal of the current transformer, and the other end is connected to the instrument;

[0016] A multi-phase transformation circuit, one end of each phase transformation circuit is electrically connected to one phase of the current transformer, and the other end is electrically connected to one end of an output circuit, and the other end of the output circuit is connected to the instrument;

[0017] A transformation ratio switching plug board, one end of which is electrically connected to the output circuit, and the other end is electrically connected to one of the transformation ratios of the phase transformation circuit;

[0018] A short-circuit plug board. When switching the transformation ratio, the short-circuit plug board electrically connects the same transformation ratio of each phase transformation circuit and the neutral point circuit at the same time to ensure that the secondary side of the current transformer will not be open-circuited.

[0019] Preferably, each phase transformation circuit is provided with two transformation ratio circuits; one end of each transformation ratio circuit is electrically connected to the current transformer, and the other end is provided with a socket; according to the transformation ratio requirement, the transformation ratio switching plug board is connected to the socket.

[0020] Further preferably, when switching the transformation ratio, the short-circuit plug board electrically connects the transformation ratio circuit with a higher transformation ratio in each phase transformation circuit at the same time.

[0021] Still further preferably, a short-circuit socket is provided on the neutral point circuit and on each transformation ratio circuit with a higher transformation ratio; when switching the transformation ratio, the short-circuit plug board is inserted into the short-circuit socket.

[0022] Further preferably, a tap ratio socket is provided at the end of each tap ratio circuit, and a tap ratio socket is also provided at the end of the output circuit; according to the tap ratio requirement, the tap ratio switching plug board is inserted into different positions to connect the tap ratio circuit and the output circuit.

[0023] The beneficial effects of the present utility model are as follows:

[0024] 1. Simple operation, no need to change wires, no tools required, and no potential safety hazards of misoperation;

[0025] 2. No need for the maintenance unit to participate, and the operating personnel can operate, saving time;

[0026] 3. No need for system power outage, improving system power supply reliability;

[0027] 4. The short-circuit plug board is reliably inserted, without the risk of CT open circuit;

[0028] The present utility model can effectively prevent the secondary side open circuit during the tap ratio switching process, improve the safety of the system; simplify the tap ratio switching operation, reduce the workload of the operating personnel and the possibility of errors. Description of the Drawings

[0029] Figure 1 is the main wiring diagram of the 132 kV power line in the prior art;

[0030] Figure 2 is the traditional multi-tap ratio current transformer wiring method in the prior art power system;

[0031] Figure 3 is the functional schematic diagram of the tap ratio switching auxiliary device of the current transformer of the present utility model;

[0032] Figure 4 is the wiring schematic diagram of the tap ratio switching auxiliary device of the current transformer of the present utility model. Detailed Embodiments

[0033] The technical solutions (including the preferred technical solutions) of the present utility model will be further described in detail below by means of the drawings and by listing some alternative embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0034] As Figure 1 and Figure 2 shown, the tap ratio switching auxiliary device of the current transformer designed by the present utility model is a passive device, which is connected in series between the current transformer and the instrument.

[0035] The auxiliary device for current transformer ratio conversion designed by the utility model includes:

[0036] A neutral point circuit 1, one end of which is connected to the neutral point terminal of the current transformer and the other end is connected to the instrument;

[0037] A multi-path phase conversion circuit 2, one end of each phase conversion circuit is electrically connected to one phase of the current transformer, and the other end is electrically connected to one end of an output circuit 3, and the other end of the output circuit 3 is connected to the instrument;

[0038] A ratio conversion plug board 4, one end of which is electrically connected to the output circuit 3 and the other end is electrically connected to one of the ratios of the phase conversion circuit 2;

[0039] A short-circuit plug board 5, when the ratio is switched, the short-circuit plug board 5 is simultaneously electrically connected to the same ratio of each phase conversion circuit 2 and the neutral point circuit 1 to ensure that the secondary side of the current transformer will not be open-circuited.

[0040] Each phase conversion circuit 2 is provided with two ratio circuits. In this embodiment, they are a large ratio circuit 2.1 with a ratio of 2000 / 1 and a small ratio circuit 2.2 with a ratio of 1600 / 1 respectively. One end of each ratio circuit is electrically connected to the current transformer and the other end is provided with a socket; according to the ratio requirement, the ratio conversion plug board 4 is connected to the socket.

[0041] A short-circuit socket is provided on the neutral point circuit 1 and on each ratio circuit with a higher ratio; when the ratio is switched, the short-circuit plug board 5 is inserted into the short-circuit socket.

[0042] A ratio socket is provided at the end of each ratio circuit, and a ratio socket is also provided at the end of the output circuit 3; according to the ratio requirement, the ratio conversion plug board 4 is inserted into different positions to connect the ratio circuit and the output circuit 3.

[0043] Taking the small ratio as an example in this embodiment, under normal operation conditions, the short-circuit plug board 5 is pulled out, and the ratio conversion plug board 4 is inserted at the currently conducting position of a2-a3, b2-b3, c2-c3 - the 1600 / 1 small ratio.

[0044] When the system operating load increases and the ratio needs to be adjusted:

[0045] First, insert the short-circuit plug board 5 to ensure that the current transformer is not open-circuited;

[0046] Then, pull out the ratio conversion plug board 4 and re-insert the ratio conversion plug board 4 at the conducting position of a1-a2, b1-b2, c1-c2 - the 2000 / 1 large ratio;

[0047] Finally, after setting the instrument to the large ratio, pull out the short-circuit plug board 5, and the switching work is completed.

[0048] The utility model can be installed on the panel of the secondary switch cabinet. All operations can be completed on the front of the switch cabinet, without the need for the construction unit to modify the secondary wiring, without power outage, and without the complex process of switching operation.

[0049] The utility model has the characteristics of convenient installation, simple and fast operation, etc., and solves many defects of the traditional method for adjusting the transformation ratio of the multi-ratio current transformer.

[0050] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the utility model, and does not limit the utility model. Any modifications, combinations, substitutions, improvements, etc. made under the spirit and principle of the utility model are included in the protection scope of the utility model.

Claims

1. An auxiliary device for current transformer ratio switching, characterized in that: The device is connected in series between the current transformer and the instrument; the device includes: A neutral point circuit, one end of which is connected to the neutral point terminal of the current transformer and the other end is connected to the instrument; A multi-path phase change circuit, one end of each phase change circuit is electrically connected to one phase of the current transformer, and the other end is electrically connected to one end of an output circuit, and the other end of the output circuit is connected to the instrument; A turns ratio switching plug board, one end of which is electrically connected to the output circuit and the other end is electrically connected to one of the turns ratios of the phase change circuit; A short-circuit plug board, when switching the turns ratio, the short-circuit plug board is simultaneously electrically connected to the same turns ratio of each phase change circuit and the neutral point circuit to ensure that the secondary side of the current transformer will not be open-circuited.

2. The current transformer ratio conversion auxiliary device according to claim 1, characterized in that: Each phase change circuit is provided with two turns ratio circuits; one end of each turns ratio circuit is electrically connected to the current transformer and the other end is provided with a socket; according to the turns ratio requirement, the turns ratio switching plug board is connected to the socket.

3. The current transformer ratio switching auxiliary device according to claim 2, characterized in that: When switching the turns ratio, the short-circuit plug board is simultaneously electrically connected to the turns ratio circuit with a higher turns ratio in each phase change circuit.

4. The current transformer ratio switching auxiliary device according to claim 3, characterized in that: A short-circuit socket is provided on the neutral point circuit and on each turns ratio circuit with a higher turns ratio; when switching the turns ratio, the short-circuit plug board is inserted into the short-circuit socket.

5. The current transformer ratio conversion auxiliary device according to claim 2, characterized in that: A turns ratio socket is provided at the end of each turns ratio circuit, and a turns ratio socket is also provided at the end of the output circuit; according to the turns ratio requirement, the turns ratio switching plug board is inserted into different positions to connect the turns ratio circuit and the output circuit.

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