A dual power supply circuit and device

Abstract

The present invention provides a dual power supply circuit and device, the power supply circuit includes a first phase sequence relay, a second phase sequence relay, a double position relay, a closing circuit and a front circuit, the coils of the first and second phase sequence relays are respectively connected to the first and second three-phase power supplies to detect their phase sequence, the front circuit includes the first normally open contact of the first phase sequence relay, the first normally open contact of the second phase sequence relay and the first coil of the double position relay connected in series, and the closing circuit includes the first branch and the second branch connected in parallel, the normally open contact of the double position relay connected in series with the first and second branches after the parallel connection, and the closing coil of the circuit breaker. The present invention first detects the phase sequence of the first and second three-phase power supplies to avoid the situation where the circuit breaker is still closed when the phase sequence is inconsistent, thereby ensuring the safety of power supply.

Description

Technical Field

[0001] The invention relates to a dual power supply circuit and a device. Background Art

[0002] With the development of society, users have higher and higher requirements for power supply continuity. In the existing low-voltage power distribution system, there are usually two power supplies. Under normal circumstances, the two power supplies supply power to the loads they are responsible for. When one power supply is accidentally cut off, the other power supply can be used as an emergency power supply and provide emergency power to all loads at the same time. This ensures that the power supply that is cut off will not be affected during the maintenance process.

[0003] However, in the existing power supply switching technology, the phase sequence of the two power supplies is not detected. The phase sequence of the two power supplies is easily different due to the influence of factors such as transformer manufacturing and line impedance. If the phase sequence is inconsistent when using the emergency power supply, it will cause a closed-loop current, causing damage to the distribution system and affecting the normal use of users. Summary of the invention

[0004] The present invention provides a dual-power supply circuit and device, which detect the phase sequence of the first and second three-phase power supplies to avoid the situation where the circuit breaker is still closed when the phase sequence is inconsistent, thereby ensuring the safety of power supply.

[0005] The present invention is achieved through the following technical solutions:

[0006] A dual-power supply circuit comprises a three-phase bus, a first three-phase power supply and a second three-phase power supply respectively connected to the three-phase bus, and a circuit breaker arranged on the three-phase bus and located between the first and second three-phase power supplies. The power supply circuit also comprises a first phase sequence relay, a second phase sequence relay, a double-position relay, a closing circuit and a front circuit. The coils of the first and second phase sequence relays are respectively connected to the first and second three-phase power supplies to detect their phase sequences. The front circuit comprises a first normally open contact of the first phase sequence relay, a first normally open contact of the second phase sequence relay and a first coil of the double-position relay connected in series. The closing circuit comprises a first branch and a second branch connected in parallel, a normally open contact of the double-position relay connected in series with the first and second branches after being connected in parallel, and a closing coil of the circuit breaker. The first branch comprises a second normally open contact of the first phase sequence relay and a normally closed contact of the second phase sequence relay connected in series, and the second branch comprises a normally closed contact of the first phase sequence relay and a second normally open contact of the second phase sequence relay connected in series.

[0007] Furthermore, it also includes a tripping circuit, which includes a second coil of a double-position relay and a tripping button connected in series, and a normally open contact of the tripping button and a tripping coil of the relay connected in series.

[0008] Furthermore, the closing circuit also includes a closing button connected in series with the closing coil.

[0009] Furthermore, it also includes a first DC power supply, the first and second branches are connected in parallel with one end connected to the positive electrode of the first DC power supply, and the closing coil is connected to the negative electrode of the first DC power supply.

[0010] Furthermore, it also includes a second DC power supply, the second coil of the double-position relay is connected to the positive electrode of the second DC power supply, and one end of the opening button is connected to the negative electrode of the second DC power supply.

[0011] Furthermore, it also includes a third DC power supply, one end of the normally open contact of the opening button is connected to the positive electrode of the third DC power supply, and the opening coil is connected to the negative electrode of the third DC power supply.

[0012] Furthermore, the first and second three-phase power supplies are both 400V low-voltage power supplies after being stepped down by a transformer.

[0013] The present invention is also achieved through the following technical solutions:

[0014] A dual power supply device comprises a cabinet and any of the dual power supply circuits as described above arranged in the cabinet.

[0015] The present invention has the following beneficial effects:

[0016] 1. The first and second phase sequence relays of the present invention are respectively connected to the first and second three-phase power supplies to detect their phase sequences. When the power is normally supplied, the circuit breaker is opened, and the first and second three-phase power supplies are both powered. If the phase sequences of the first and third three-phase power supplies are consistent, the first and second phase sequence relay coils are respectively powered, and the pre-circuit is turned on, and the first coil of the double-position relay is powered, so that the normally open contact of the double-position relay is closed, providing a precondition for the closing of the circuit breaker. Otherwise, the normally open contact of the double-position relay will not be closed, and the closing circuit of the circuit breaker cannot be turned on, thereby avoiding the situation where the circuit breaker is still closed when the phase sequence is inconsistent, and further avoiding the normal use of the power distribution system or the user due to the generation of the closing current; furthermore, when the power is normally supplied and the phase sequence is consistent, the first branch and the second branch are not conductive. When the first three-phase power supply or the second three-phase power supply is powered off, the normally open contact of the double-position relay is still closed because the double-position relay does not lose its position when the power is off. At this time, one of the first branch or the second branch can be conductive, so the closing circuit is conductive and the circuit breaker can be closed. After closing, the double-position relay will be reset and its normally open contact will be disconnected. If the circuit breaker needs to be closed again, the first coil of the double-position relay must be energized again after the first and second three-phase power supplies are powered again. Therefore, in the present invention, when only one three-phase power supply is used (i.e.), the circuit breaker can only be closed once, which can effectively avoid wrong closing and is safer. The present invention can realize opening and closing control by only using the phase sequence relay and the double-position relay, and the circuit is simple and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is further described in detail below with reference to the accompanying drawings.

[0018] Figure 1 The schematic diagram of the circuit of the present invention is shown in FIG.

[0019] Among them, 1. transformer; 2. three-phase bus; 3. first three-phase power supply; 4. second three-phase power supply; K1. circuit breaker; K2. main transformer circuit breaker; Y1. first phase sequence relay coil; Y2. second phase sequence relay coil; J1. first coil of double-position relay; J2. second coil of double-position relay; HA. closing button; HQ. closing coil; TA. opening button; TQ. opening coil; DC1. first DC power supply; DC2. second DC power supply; DC3. third DC power supply. DETAILED DESCRIPTION

[0020] The dual power supply device includes a cabinet and a dual power supply circuit arranged in the cabinet, wherein the dual power supply circuit includes a three-phase bus, a first three-phase power supply 3, a second three-phase power supply 4, a circuit breaker K1, a first phase sequence relay, a second phase sequence relay, a double-position relay, a closing circuit, an opening circuit and a front circuit. The first three-phase power supply 3 and the second three-phase power supply 4 are both 400V low-voltage power supplies after the 10kV high-voltage power supply is stepped down by a transformer 1. The first three-phase power supply 3 and the second three-phase power supply 4 are respectively connected to the three-phase bus through two main transformer circuit breakers K2. The circuit breaker K1 is arranged on the three-phase bus and is located between the first three-phase power supply 3 and the second three-phase power supply 4. Under normal circumstances, the circuit breaker K1 is in an opening state, and the first three-phase power supply 3 and the second three-phase power supply 4 respectively supply power to their corresponding loads.

[0021] The first phase sequence relay coil Y1 and the second phase sequence relay coil Y2 are respectively connected to the first three-phase power supply 3 and the second three-phase power supply 4 to detect their phase sequence. The pre-circuit includes the first normally open contact Y1-1 of the first phase sequence relay, the first normally open contact Y2-1 of the second phase sequence relay and the first coil J1J1 of the double-position relay. One end of the first normally open contact Y1-1 of the first phase sequence relay is connected to the positive pole of the first DC power supply DC1, and the other end is connected to one end of the first normally open contact Y2-1 of the second phase sequence relay. The other end of the first normally open contact Y2-1 of the second phase sequence relay is connected to one end of the first coil J1 of the double-position relay, and the other end of the first coil J1 of the double-position relay is connected to the negative pole of the first DC power supply DC1. When the first three-phase power supply 3 and the second three-phase power supply 4 are both powered and the phase sequence is consistent, the pre-circuit will be turned on, and the first coil J1 of the double-position relay will be powered, so that the normally open contact J1-1 of the double-position relay is closed, providing a precondition for the conduction of the closing circuit.

[0022] The closing circuit includes a first branch, a second branch, a normally open contact J1-1 of a double-position relay, a closing button HA and a closing coil HQ of a circuit breaker K1. The first branch and the second branch are connected in parallel. The first branch includes a second normally open contact Y1-2 of a first phase sequence relay and a normally closed contact Y2-3 of a second phase sequence relay connected in series in sequence. The second branch includes a normally closed contact Y1-3 of a first phase sequence relay and a second normally open contact Y2-2 of a second phase sequence relay connected in series in sequence. One end of the first branch and the second branch after being connected in parallel is connected to the positive pole of the first DC power supply DC1, and the other end is connected to one end of the normally open contact J1-1 of the double-position relay. The other end of the normally open contact J1-1 of the double-position relay is connected to the closing coil HQ of the circuit breaker K1 through the closing button HA, and the closing coil HQ is connected to the negative pole of the first DC power supply DC1. When the first three-phase power supply 3 or the second three-phase power supply 4 cannot supply power, press the closing button HA to send a closing signal. At this time, the first phase sequence relay coil Y1 or the second phase sequence relay coil Y2 loses power, the first branch or the second branch is turned on, the closing circuit is turned on, and the closing coil HQ is energized, so the circuit breaker K1 can be closed.

[0023] The opening circuit includes the second coil J2 of the double-position relay and the opening button TA connected in series, as well as the normally open contact of the opening button TA and the opening coil TQ of the relay connected in series. The second coil J2 of the double-position relay is connected to the positive pole of the second DC power supply DC2, one end of the opening button TA is connected to the negative pole of the second DC power supply DC2, one end of the normally open contact of the opening button TA is connected to the positive pole of the third DC power supply DC3, and the opening coil TQ is connected to the negative pole of the third DC power supply DC3. When the power supply that cannot be supplied is restored, the opening button TA is pressed to send an opening signal. At this time, the second coil J2 of the double-position relay is energized, so that the normally open contact of the double-position relay is disconnected, ensuring that the closing circuit cannot be turned on again, and then the opening button TA is closed, so that the normally open contact of the opening button TA is closed, and the opening coil TQ of the circuit breaker K1 is energized, so that the circuit breaker K1 can be opened.

[0024] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of implementation of the present invention. That is, equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the specification should still fall within the scope covered by the patent of the present invention.

Claims

1. A dual power supply circuit, comprising a three-phase bus, a first three-phase power supply and a second three-phase power supply respectively connected to the three-phase bus, and a circuit breaker arranged on the three-phase bus and located between the first and second three-phase power supplies, characterized in that: The power supply circuit also includes a first phase sequence relay, a second phase sequence relay, a double position relay, a closing circuit and a front circuit. The coils of the first and second phase sequence relays are respectively connected to the first and second three-phase power supplies to detect their phase sequences. The front circuit includes a first normally open contact of the first phase sequence relay, a first normally open contact of the second phase sequence relay and a first coil of the double position relay connected in series. The closing circuit includes a first branch and a second branch connected in parallel, a normally open contact of the double position relay connected in series with the first and second branches after being connected in parallel, and a closing coil of the circuit breaker. The first branch includes a second normally open contact of the first phase sequence relay and a normally closed contact of the second phase sequence relay connected in series, and the second branch includes a normally closed contact of the first phase sequence relay and a second normally open contact of the second phase sequence relay connected in series. It also includes an opening circuit, which includes a second coil of the double position relay and an opening button connected in series, and a normally open contact of the opening button and an opening coil of the relay connected in series.

2. A dual power supply circuit according to claim 1, characterized in that: The closing circuit also includes a closing button connected in series with the closing coil.

3. A dual power supply circuit according to claim 1 or 2, characterized in that: It also includes a first DC power supply, wherein the first and second branches are connected in parallel with one end thereof connected to the positive electrode of the first DC power supply, and the closing coil is connected to the negative electrode of the first DC power supply.

4. A dual power supply circuit according to claim 3, characterized in that: It also includes a second DC power supply, the second coil of the double-position relay is connected to the positive electrode of the second DC power supply, and one end of the opening button is connected to the negative electrode of the second DC power supply.

5. The dual power supply circuit according to claim 1, characterized in that: It also includes a third DC power supply, one end of the normally open contact of the opening button is connected to the positive electrode of the third DC power supply, and the opening coil is connected to the negative electrode of the third DC power supply.

6. A dual power supply circuit according to claim 1 or 2, characterized in that: The first and second three-phase power supplies are both 400V low-voltage power supplies after being stepped down by a transformer.

7. A dual power supply device, characterized in that: It comprises a cabinet and a dual power supply circuit as claimed in any one of claims 1 to 6 arranged in the cabinet.

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