Main and standby power supply switching loop of transformer cooling system

Abstract

The utility model provides a main and standby power supply switching loop of a transformer cooling system, which comprises three paths of power supplies, namely a path I power supply, a path II power supply and a path III power supply, a live wire of each power supply of the three power supplies is provided with a first circuit breaker, a phase sequence relay, a contactor, an intermediate relay and a surge protector; the phase sequence relay is arranged between the contactor and the circuit breaker, and the contactor supplies power to a transformer cooling system after being conducted; a first live wire is led out from the live wire between the circuit breaker and the phase sequence relay of each power supply; a second live wire is led out between the surge protector and the zero line, and contacts of different devices are arranged on the first live wire and the second live wire; the state between the contacts is changed through on-off of one power supply, so that on-off of the other two power supplies is changed, and automatic switching-on and switching-off of the standby power supply can be realized.

Description

Technical Field

[0001] This utility model relates to the field of transformer cooling control, and more particularly to a main and backup power switching circuit for a transformer cooling system. Background Technology

[0002] Existing transformer cooling systems typically use two station service transformers from the same substation as their power source. Phase sequence relays are used to monitor and automatically switch the two power sources on and off. However, phase sequence relays have a high failure rate when operating under energized conditions for extended periods. Sometimes, both phase sequence relays may fail simultaneously, causing a complete shutdown of the transformer cooling system. A complete shutdown of the transformer cooling system leads to a rapid increase in transformer temperature, which can cause serious damage to the transformer.

[0003] Therefore, in order to solve the above-mentioned technical problems, it is urgent to propose a new technical approach. Utility Model Content

[0004] In view of this, in order to avoid the transformer cooling system from shutting down completely due to the simultaneous failure of two phase sequence relays, this utility model proposes a main and backup power switching circuit for the transformer cooling system.

[0005] This utility model provides a main and backup power switching circuit for a transformer cooling system, including three power supplies: power supply I, power supply II, and power supply III.

[0006] Each of the three power supplies is equipped with a first circuit breaker, a phase sequence relay, a contactor, an intermediate relay, and a surge protector on its live wire. The phase sequence relay is located between the contactor and the circuit breaker, and supplies power to the transformer cooling system after the contactor is turned on. A first live wire is led out from the live wire between the circuit breaker and the phase sequence relay of each power supply. The first live wire is connected to the neutral wire after being connected in series with the normally open contact of the surge protector, the phase sequence relay, and the coil of the intermediate relay.

[0007] A second live wire is drawn between the surge protector and the neutral wire. In power supply circuits I and II, the second live wire is connected in series with the control switch, the normally open contact of the intermediate relay of the respective power supply circuit, the normally closed contact of the contactor of the other two power supply circuits, and the coil of the contactor of the respective power supply circuit. In power supply circuit III, the second live wire is connected in series with the control switch, the normally open contact of the intermediate relay of the respective power supply circuit, the normally closed contact of the intermediate relay of the other two power supply circuits, and the coil of the contactor of the respective power supply circuit.

[0008] Furthermore, the live wire between the surge protector and the normally open contact of the intermediate relay on power supply I and power supply II is divided into two paths. One path is directly connected to the control switch, and the other path is connected in series with the control switch and the normally closed contact of the intermediate relay on the other power supply circuit.

[0009] The other power supply circuit includes only power supply I and power supply II.

[0010] Furthermore, the control switch for power supply I is provided with a first contact, a second contact, a third contact, and a fourth contact; the control switch for power supply II is provided with a fifth contact, a sixth contact, a seventh contact, and an eighth contact; and the control switch for power supply III is provided with a ninth contact and a tenth contact.

[0011] When power supply I is working, contacts 1 and 2, 5 and 6, and 9 and 10 are closed; contacts 3 and 4, and contacts 7 and 8 remain open.

[0012] When the II power supply is working, the third and fourth contacts, the seventh and eighth contacts, and the ninth and tenth contacts are turned on respectively; the first and second contacts, as well as the fifth and sixth contacts, remain open respectively.

[0013] Furthermore, it also includes a second circuit breaker, which is installed on each of the three power supplies. The normally open contact of the second circuit breaker is located between the first circuit breaker and the surge protector.

[0014] Furthermore, each of the three power supplies is equipped with three live wires, one of which is connected to the normally open contact of the phase sequence relay and the circuit breaker respectively.

[0015] Furthermore, the normally closed contacts of the phase sequence relays for each power supply are connected to the alarm system.

[0016] The beneficial effects of this utility model are as follows: This utility model introduces a third power source, which can still ensure the normal operation of the transformer cooling system when the station power supply or both phase sequence relays fail; in addition, this utility model also adds a surge protector, which can protect the phase sequence relays from damage in the event of lightning or operational overvoltage. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0018] Figure 1 This is a structural diagram of the main and backup power switching circuit of the transformer cooling system of this utility model. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings:

[0020] This utility model provides a main / backup power supply switching circuit for a transformer cooling system, which achieves automatic switching between main and backup power supplies through a circuit breaker QF, a contactor KM, an intermediate relay KA, and a control switch SA. Figure 1 As shown ( Figure 1 QF1 is the first circuit breaker and 1QF is the second circuit breaker. Specifically, it includes three power supplies: power supply I, power supply II and power supply III. Power supply I and power supply II are the power supply inside the station, and power supply III is the power supply outside the station.

[0021] Each of the three power supplies is equipped with a first circuit breaker, a phase sequence relay, a contactor, an intermediate relay, and a surge protector on its live wire. The phase sequence relay is located between the contactor and the circuit breaker, and supplies power to the transformer cooling system after the contactor is turned on. A first live wire is led out from the live wire between the circuit breaker and the phase sequence relay of each power supply. The first live wire is connected to the neutral wire after being connected in series with the normally open contact of the surge protector, the phase sequence relay, and the coil of the intermediate relay.

[0022] A second live wire is drawn between the surge protector and the neutral wire. In power supply circuits I and II, the second live wire is connected in series with the control switch, the normally open contact of the intermediate relay of the respective power supply circuit, the normally closed contact of the contactor of the other two power supply circuits, and the coil of the contactor of the respective power supply circuit. In power supply circuit III, the second live wire is connected in series with the control switch, the normally open contact of the intermediate relay of the respective power supply circuit, the normally closed contact of the intermediate relay of the other two power supply circuits, and the coil of the contactor of the respective power supply circuit.

[0023] Specifically, three live wires are provided on the power supply circuit I, namely L11, L12 and L13. The first live wire of the power supply circuit I is led out from the live wire L13 between the circuit breaker QF1 and the phase sequence relay KV1. This first live wire is connected to the neutral wire after being connected in series with the surge protector SPD1, the normally open contact of the phase sequence relay KV1 and the coil of the intermediate relay KA1. The second live wire of the power supply circuit I is led out from the surge protector SPD1 and the neutral wire. This second live wire is connected in series with the control switch SA, the normally open contact of the intermediate relay KA1, the normally closed contact of the contactor KM2, the normally closed contact of the contactor KM3 and the coil of the contactor KM1. After the first live wire and the second live wire are combined, they are connected to the neutral wire. That is, the current passing through the coil of the intermediate relay KA1 and the coil of the contactor KM1 is combined and then connected to the neutral wire.

[0024] The normally open contact of contactor KM3 is also connected to the prompting system. When the III power supply is powered, contactor KM3 is in the energized state, the normally open contact of contactor KM3 is open, the prompting system receives the signal and sends a signal to the main control room to prompt that the external power supply is put into use.

[0025] The power supply circuit II has three live wires, namely L21, L12, and L23. The first live wire of the power supply circuit II is led out from the live wire L23 between the circuit breaker QF2 and the phase sequence relay KV2. This first live wire is connected to the neutral wire after being connected in series with the surge protector SPD2, the normally open contact of the phase sequence relay KV2, and the coil of the intermediate relay KA2. The second live wire of the power supply circuit II is led out from the surge protector SPD2 and the neutral wire. This second live wire is connected in series with the control switch SA, the normally open contact of the intermediate relay KA2, the normally closed contact of the contactor KM1, the normally closed contact of the contactor KM3, and the coil of the contactor KM2. After the first and second live wires are combined, it is connected to the neutral wire. That is, the current passing through the coil of the intermediate relay KA2 and the coil of the contactor KM2 is combined and then connected to the neutral wire.

[0026] The third power supply has three live wires, L31, L32, and L33. The first live wire of the third power supply is drawn from live wire L33 between circuit breaker QF3 and phase sequence relay KV3. This first live wire is connected in series with surge protector SPD3, the normally open contact of phase sequence relay KV3, and the coil of intermediate relay KA3, and then connected to the neutral wire. The second live wire of the third power supply is drawn between surge protector SPD3 and the neutral wire. This second live wire is connected in series with control switch SA, the normally open contact of intermediate relay KA3, the normally closed contact of intermediate relay KA1, the normally closed contact of intermediate relay KA2, and the coil of contactor KM3. The current from the first and second live wires is combined and then connected to the neutral wire; that is, the current passing through the coils of intermediate relay KA3 and contactor KM3 is combined and then connected to the neutral wire. This structure enables automatic power switching and prevents the transformer cooling system from stopping operation.

[0027] In this embodiment, the live wire between the surge protector and the normally open contact of the intermediate relay on power supply I and power supply II is divided into two paths. One path is directly connected to the control switch, and the other path is connected in series with the control switch and the normally closed contact of the intermediate relay on the other power supply circuit.

[0028] The other power supply circuit includes only power supply I and power supply II.

[0029] Specifically, in the power supply circuit I, the live wire between the normally open contact of the surge protector SPD1 and the intermediate relay KA1 is divided into two paths. One path is directly connected to the first and second contacts of the control switch, and the other path is connected in series with the third and fourth contacts of the control switch and the normally closed contact of the intermediate relay KA2.

[0030] In the second power supply circuit, the live wire between the surge protector SPD2 and the normally open contact of the intermediate relay KA2 is divided into two paths. One path is directly connected to the fifth and sixth contacts of the control switch, and the other path is connected in series with the seventh and eighth contacts of the control switch and the normally closed contact of the intermediate relay KA1. This configuration allows the engine cooling system to be powered using only one power supply circuit.

[0031] In this embodiment, a second circuit breaker is also included. Each of the three power supplies is equipped with a second circuit breaker, and the normally open contact of the second circuit breaker is located between the first circuit breaker and the surge protector. Figure 1 As shown.

[0032] In this embodiment, the control switch for power supply I is provided with a first contact, a second contact, a third contact, and a fourth contact; the control switch for power supply II is provided with a fifth contact, a sixth contact, a seventh contact, and an eighth contact; and the control switch for power supply III is provided with a ninth contact and a tenth contact.

[0033] When power supply I is working, contacts 1 and 2, 5 and 6, and 9 and 10 are closed; contacts 3 and 4, and contacts 7 and 8 remain open.

[0034] When the II power supply is working, the third and fourth contacts, the seventh and eighth contacts, and the ninth and tenth contacts are turned on respectively; the first and second contacts, as well as the fifth and sixth contacts, remain open respectively.

[0035] In this embodiment, each of the three power sources has three live wires, which are three-phase power. One of the live wires is connected to the normally open contact of the phase sequence relay and the circuit breaker, respectively.

[0036] In this embodiment, the normally closed contact of the phase sequence relay of each power supply is connected to the alarm system;

[0037] When a power supply circuit suddenly experiences an abnormality such as phase loss or overvoltage while operating normally, the normally closed contact of the phase sequence relay changes from cut-off to conduction, and the alarm system sends an alarm signal to the main control room; this is used to alert maintenance personnel to the specific damaged power supply.

[0038] More specifically, this application first selects power supply I for supply. When power supply I fails, power supply II automatically switches on to provide power. When power supply I recovers, power supply II automatically disconnects. When both power supply I and power supply II fail, power supply III automatically switches on to provide power. The principle is as follows:

[0039] When power supply I is operating normally, the first and second contacts, the fifth and sixth contacts, and the ninth and tenth contacts of control switch SA are closed. The normally open contacts of the second circuit breaker 1QF on power supply I are closed, and the phase sequence relay KV1 monitors the power circuit. When the voltage is normal, the normally open contact of the phase sequence relay KV1 is closed, supplying power to the coil of intermediate relay KA1. When intermediate relay KA1 is energized, its normally open contact is closed, supplying power to the coil of contactor KM1. The normally closed contact of intermediate relay KA1 is open. When contactor KM1 is energized, its normally open contact is closed, and power supply I supplies power to the transformer cooling system. The normally closed contact of contactor KM1 is open, disconnecting power supply II from contactor KM2, thus preventing power supply I, II, and III from simultaneously supplying power to the transformer cooling system. When the power supply to circuit I is abnormal, it cannot supply power to the intermediate relay KA1. At this time, the normally open contact of the intermediate relay KA1 is in the open state; consequently, it cannot supply power to the coil of contactor KM1, and the power supply from circuit I to the transformer cooling system is disconnected.

[0040] When power supply I is abnormal and power supply II is normal, contacts 3 and 4, 7 and 8, and 9 and 10 are closed. The normally open contact of the second circuit breaker 2QF on power supply II is closed, as is the normally open contact of the sequence relay KV2, supplying power to the coil of intermediate relay KA2. When intermediate relay KA2 is energized, its normally open contact closes and its normally closed contact opens. At this time, power supply II supplies power to the coil of contactor KM2, and the power supply circuit for contactor KM3 is disconnected. After contactor KM2 is energized, its normally open contact closes, and power supply II supplies power to the transformer cooling system. When power supply I returns to normal, the coil of intermediate relay KA1 is energized, causing its normally closed contact to open, thus disconnecting the power supply to the coil of contactor KM2. At this time, power supply II is automatically disconnected.

[0041] When the power supply to circuit II is abnormal, the normally open contact of the sequence relay KV2 opens, preventing power supply to the intermediate relay KA2, which in turn prevents power supply to the contactor KM2. This causes the normally open contact of the contactor KM2 to open, thus preventing power supply to the transformer cooling system.

[0042] When both power supply I and power supply II are abnormal, and power supply III is normal, the normally open contact of the second circuit breaker 3QF is open, and the normally open contact of the sequence relay KV3 is open, supplying power to the coil of the intermediate relay KA3. After the intermediate relay KA3 is energized, its normally open contact is open. Since both power supply I and power supply II are abnormal, intermediate relays KA1 and KA2 are not energized, and their normally closed contacts remain open. The coil of contactor KM3 is energized, and its normally open contact is open, supplying power to the transformer cooling system via power supply III. When either power supply I or power supply II returns to normal, taking power supply II as an example, intermediate relay KA2 is energized, and its normally closed contact opens. Power supply III cannot supply power to the coil of contactor KM3, and the normally open contact of contactor KM3 returns to the closed state, thus cutting off the power supply from power supply III to the transformer cooling system. At this time, power supply II supplies power to the transformer cooling system. Abnormalities refer to overvoltage, undervoltage, and phase loss, etc. This utility model can realize the automatic switching of backup power and can automatically reset after the power supply returns to normal.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A main / standby power switching circuit for a transformer cooling system, characterized in that: It includes three power supplies: power supply I, power supply II, and power supply III. Each of the three power supplies is equipped with a first circuit breaker, a phase sequence relay, a contactor, an intermediate relay, and a surge protector on its live wire. The phase sequence relay is located between the contactor and the circuit breaker, and supplies power to the transformer cooling system after the contactor is turned on. A first live wire is led out from the live wire between the circuit breaker and the phase sequence relay of each power supply. The first live wire is connected to the neutral wire after being connected in series with the normally open contact of the surge protector, the phase sequence relay, and the coil of the intermediate relay. A second live wire is drawn between the surge protector and the neutral wire. In power supply circuits I and II, the second live wire is connected in series with the control switch, the normally open contact of the intermediate relay of the respective power supply circuit, the normally closed contact of the contactor of the other two power supply circuits, and the coil of the contactor of the respective power supply circuit. In power supply circuit III, the second live wire is connected in series with the control switch, the normally open contact of the intermediate relay of the respective power supply circuit, the normally closed contact of the intermediate relay of the other two power supply circuits, and the coil of the contactor of the respective power supply circuit.

2. The main / standby power switching circuit of the transformer cooling system according to claim 1, characterized in that: The live wire between the surge protector and the normally open contact of the intermediate relay on power supply circuit I and power supply circuit II is divided into two paths. One path is directly connected to the control switch, and the other path is connected in series with the control switch and the normally closed contact of the intermediate relay on the other power supply circuit. The other power supply circuit includes only power supply I and power supply II.

3. The main / standby power switching circuit of the transformer cooling system according to claim 1 or claim 2, characterized in that: The control switch for power supply I has a first contact, a second contact, a third contact, and a fourth contact; the control switch for power supply II has a fifth contact, a sixth contact, a seventh contact, and an eighth contact; and the control switch for power supply III has a ninth contact and a tenth contact. When power supply I is working, contacts 1 and 2, 5 and 6, and 9 and 10 are connected respectively; The third and fourth contacts, as well as the seventh and eighth contacts, remain open. When the II power supply is working, the third and fourth contacts, the seventh and eighth contacts, and the ninth and tenth contacts are turned on respectively; The first and second contacts, as well as the fifth and sixth contacts, remain open.

4. The main / standby power switching circuit of the transformer cooling system according to claim 1, characterized in that: It also includes a second circuit breaker, which is installed on each of the three power supplies. The normally open contact of the second circuit breaker is located between the first circuit breaker and the surge protector.

5. The main / standby power switching circuit of the transformer cooling system according to claim 1, characterized in that: Each of the three power supplies has three live wires, one of which is connected to the normally open contact of the phase sequence relay and the circuit breaker.

6. The main / standby power switching circuit of the transformer cooling system according to claim 1, characterized in that: The normally closed contacts of the phase sequence relays for each power supply are connected to the alarm system.

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