Safety locking device for switching of self-contained power supply

Abstract

The utility model relates to a self-contained power supply switching safety locking device which is characterized in that a cold standby monitoring loop is arranged at a switch and a disconnecting link of a transformer outgoing line main cabinet, an auxiliary contact and a first relay are arranged on the cold standby monitoring loop, the auxiliary contact is closed in a cold standby state and is mutually locked with a starting loop of a generator, and the first relay is connected with a second relay. The generator can be started only under the condition that the transformer outgoing line power switch is in cold standby. The device can improve the safety of power supply switching and avoid reverse power supply.

Description

Technical Field

[0001] The utility model relates to the technical field of standby power supply switching, in particular to a self-contained power supply switching safety locking device. Background Art

[0002] In recent years, accidents such as personal injury and equipment damage caused by self-contained power supplies feeding back into the power grid have occurred frequently. Therefore, adopting proper switching devices for self-contained power supplies is one of the important measures to prevent self-contained power supplies from feeding back into the power grid and to ensure personal and power grid safety.

[0003] The technical requirements for self-contained power supply in the State Grid Safety Regulations emphasize that: "For larger capacity generator sets or those with special requirements for power supply reliability, electrical interlocks can be used, but it should be ensured that in any case, only one power supply is put into operation without the possibility of incorrect parallel connection." That is to say, larger capacity generator sets can use electrical interlocks, but there are certain difficulties and risks in the management of electrical interlocks, which means that electrical interlocks are unreliable. Mainly manifested in: the electrical interlock has no obvious disconnection point, so when switching to the backup power supply, it is impossible to directly judge whether it is completely disconnected from the public power switch; once the electrical interlock fails or the contact closure is incorrect, it may be mistakenly paralleled, causing reverse power supply to the grid side. Therefore, accidents of reverse power supply from self-contained power supply due to electrical interlock failure occur from time to time. Summary of the invention

[0004] The utility model aims to provide a self-contained power supply switching safety locking device, which can improve the safety of power supply switching and avoid power supply reverse transmission.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a self-contained power supply switching safety locking device, a cold standby monitoring circuit is arranged at the switch and knife switch of the transformer outlet main cabinet, and the cold standby monitoring circuit is provided with auxiliary contacts and a first relay. The auxiliary contacts are closed in the cold standby state and are locked with the starting circuit of the generator, so that the generator can only be started when the transformer outlet power switch is in the cold standby state.

[0006] Furthermore, the auxiliary contact is a travel switch auxiliary contact, and when the trolley is in place and in a cold standby state, the travel switch auxiliary contact is closed.

[0007] Furthermore, the first relay coil is connected in series to the cold standby monitoring circuit, and the normally open contact of the first relay is connected in series to the starting circuit of the generator. After the auxiliary contact is closed, the first relay coil is energized and the normally open contact of the first relay is closed.

[0008] Furthermore, an indicator light for monitoring the switch status on the low-voltage side of the transformer is provided in the starting circuit of the generator. The indicator light is connected in series with the generator starting switch and the normally open contact of the first relay. When the generator starting switch is closed and the normally open contact of the first relay is closed, the indicator light is on.

[0009] Furthermore, an ignition switch and a second relay are provided in the starting circuit of the generator. The ignition switch and the second relay coils are connected in series and then connected in parallel with the connecting circuit of the indicator light. Then the entire parallel circuit is connected in series with the generator starting switch and the normally open contact of the first relay; the normally open contact of the second relay is connected in series with the generator starting motor.

[0010] Furthermore, a diode is connected in series on the connection circuit of the indicator light.

[0011] Furthermore, the generator is a diesel generator.

[0012] Compared with the prior art, the utility model has the following beneficial effects: auxiliary contacts and relays are added to the switches and knife switches of the transformer outlet cabinet (0.4KV) to form a cold standby monitoring circuit, which is mutually locked with the generator start circuit, so that the transformer outlet power switch (0.4KV) can only start the generator when it is in cold standby, ensuring that power cannot be reversed to the power grid under any circumstances. The device can improve the safety of power switching, avoid the generator power supply from reversely transmitting power to the power grid side, and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a circuit schematic diagram of a cold standby monitoring circuit in an embodiment of the utility model;

[0014] Figure 2 The figure is a circuit diagram of the starting circuit of the generator in the embodiment of the utility model. DETAILED DESCRIPTION

[0015] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0016] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0017] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0018] like Figure 1-2 As shown, this embodiment provides a self-contained power supply switching safety locking device, a cold standby monitoring circuit is set at the switch and knife switch of the transformer outlet main cabinet (0.4KV), the cold standby monitoring circuit is provided with an auxiliary contact S1 and a first relay KM1, the auxiliary contact S1 is closed in the cold standby state, and is mutually locked with the starting circuit of the generator, so that the transformer outlet power switch (0.4KV) can only start the generator in the cold standby state.

[0019] In this embodiment, the auxiliary contact S1 is a travel switch auxiliary contact. When the trolley is in place and in a cold standby state, the travel switch auxiliary contact is closed.

[0020] The coil of the first relay KM1 is connected in series to the cold standby monitoring circuit, and the normally open contact of the first relay KM1 is connected in series to the starting circuit of the generator. After the auxiliary contact S1 is closed, the coil of the first relay KM1 is energized and the normally open contact of the first relay KM1 is closed.

[0021] An indicator light for monitoring the switch status of the low-voltage side of the transformer is provided in the starting circuit of the generator. The indicator light is connected in series with the generator starting switch S3 and the normally open contact of the first relay KM1. When the generator starting switch S3 is closed and the normally open contact of the first relay KM1 is closed, the indicator light is on. A diode D1 is also connected in series to the connection line of the indicator light.

[0022] An ignition switch S2 and a second relay KM2 are also provided in the generator starting circuit. The ignition switch S2 and the second relay KM2 coils are connected in series and then connected in parallel with the connection line of the indicator light. Then the entire parallel circuit is connected in series with the generator starting switch S3 and the normally open contact of the first relay KM1. The normally open contact of the second relay KM2 is connected in series with the generator starting motor M.

[0023] In this embodiment, the generator is a diesel generator.

[0024] During operation, in the cold standby state, the auxiliary contacts of the travel switch are closed, the KM1 coil is energized, and the KM1 switch is closed. At this time, when the circuit starting switch S3 of the diesel generator is closed, and the auxiliary contacts of the switch and knife switch of the transformer outlet main cabinet (0.4KV) are in the cold standby state, the circuit of the diesel generator is connected and the indicator light is on. At this time, after the ignition switch S2 is activated, the circuit passes through the starting switch S3, and the cold standby relay on the low-voltage side of the main transformer corresponds to the energized contact, the KM2 relay. At this time, the KM2 coil is energized and the normally open contact corresponding to KM2 is energized, so that the generator starter motor M can be energized and the backup power supply can be smoothly input to ensure that it will not be backflowed to the power grid.

[0025] For large-capacity generators, the breaking capacity of double-throw four-pole knife switches cannot meet the requirements, and double-throw four-pole switches (electrical interlocks) must be used. Since the self-contained power supply switching device is electrically interlocked and has no obvious disconnection point, it is not conducive to on-site inspection. In order to prevent accidents caused by the false closure of electrical contacts, the following measures are taken for users who use electrical interlocks: Transformers with a capacity of 800kVA and below must use GGD cabinets, and the switching device uses double-throw four-pole knife switches, and there are obvious disconnection points to achieve synchronous switching of neutral and phase lines. For transformers with a capacity of more than 800kVA, it is allowed to use GGK cabinets with electrical interlocks, but they should be double circuit breakers (four-pole) plus electrical interlocks to realize power transfer between the main and standby power sources, and the electrical interlocks must comply with national and local standards and power industry regulations. In addition, auxiliary contacts and relays are installed at the switches and knife switches of the transformer outlet cabinet (0.4KV) to interlock the starting circuit of the generator, so that the transformer outlet power switch (0.4KV) can only start the generator when it is in cold standby mode, ensuring that power cannot be reversed to the grid under any circumstances.

[0026] The above is only the preferred embodiment of the utility model, and does not limit the utility model in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the utility model without departing from the technical solution of the utility model still belongs to the protection scope of the technical solution of the utility model.

Claims

1. A self-contained power supply switching safety locking device, characterized in that: A cold standby monitoring circuit is arranged at the switch and knife switch of the transformer outlet main cabinet. Auxiliary contacts and a first relay are arranged on the cold standby monitoring circuit. The auxiliary contacts are closed in the cold standby state and interlocked with the starting circuit of the generator, so that the generator can only be started when the transformer outlet power switch is in the cold standby state.

2. A self-contained power supply switching safety locking device according to claim 1, characterized in that: The auxiliary contact is a travel switch auxiliary contact. When the trolley is in place and in a cold standby state, the travel switch auxiliary contact is closed.

3. A self-contained power supply switching safety locking device according to claim 1, characterized in that: The first relay coil is connected in series to the cold standby monitoring circuit, and the normally open contact of the first relay is connected in series to the starting circuit of the generator. After the auxiliary contact is closed, the first relay coil is energized and the normally open contact of the first relay is closed.

4. A self-contained power supply switching safety locking device according to claim 3, characterized in that: An indicator light for monitoring the switch status on the low-voltage side of the transformer is provided in the starting circuit of the generator. The indicator light is connected in series with the generator starting switch and the normally open contact of the first relay. When the generator starting switch is closed and the normally open contact of the first relay is closed, the indicator light is on.

5. A self-contained power supply switching safety locking device according to claim 4, characterized in that: An ignition switch and a second relay are also provided in the starting circuit of the generator. The ignition switch and the second relay coils are connected in series and then connected in parallel with the connecting circuit of the indicator light. Then the entire parallel circuit is connected in series with the generator starting switch and the normally open contact of the first relay; the normally open contact of the second relay is connected in series with the generator starting motor.

6. A self-contained power supply switching safety locking device according to claim 4, characterized in that: A diode is also connected in series on the connection circuit of the indicator light.

7. A self-contained power supply switching safety locking device according to claim 1, characterized in that: The generator is a diesel generator.

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