Control loop for rapid switching of low-voltage equipment

Abstract

The utility model provides a control loop for rapid switching of low-voltage equipment, a terminal of a main equipment control loop is connected with a main power supply cabinet, a terminal of a standby equipment control loop is connected with a standby power supply cabinet, and a terminal strip of the main equipment control loop is connected with a normally closed point of an intermediate relay after being dismounted. A normally open contact of the intermediate relay is connected with a standby equipment control loop terminal, a standby equipment control loop is sequentially connected with a 2P circuit breaker, a two-position change-over switch and the intermediate relay from a wire outlet end of a standby power supply cabinet, one end of the two-position change-over switch is connected with an L wire of the 2P circuit breaker, and the other end of the two-position change-over switch is connected with a coil wiring end of the intermediate relay. The N line end of the 2P circuit breaker is connected with the coil wiring end of the intermediate relay; the leading-out ends of the main equipment control loop and the standby equipment control loop are in same-phase short circuit and then are connected with a load; according to the utility model, through a normally open / normally closed switching control principle of the change-over switch and the intermediate relay, rapid switching of a main loop and a standby loop is realized, and fault processing time is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of circuit control, and particularly relates to a control circuit for rapid switching of low-voltage equipment. Background Art

[0002] During the production process of metallurgical furnaces, the smoke exhaust and dust collection fan, as a key safety production equipment, must not fail. Therefore, it is necessary to minimize the risk of the fan tripping due to failure. Existing methods, such as adding a set of standby control circuits, require re-laying relevant cables, installing a standby control cabinet, DCS control screens, etc. These methods are cumbersome and costly. Moreover, the wiring of the terminal block of the main control circuit of the equipment is simple and the function is single. When a failure occurs in the equipment control cabinet, it will cause passive repair, and the main control circuit needs to be powered off before repair, affecting the overall operation of the production system. Content of the Utility Model

[0003] Aiming at the problems and safety risk factors caused by the tripping of key equipment in metallurgical furnaces to the production system, the utility model provides a control circuit for rapid switching of low-voltage equipment, which realizes the rapid switching of the smoke exhaust fan to the standby control circuit, and performs fault troubleshooting under the normal opening state of the smoke exhaust fan to eliminate safety risks.

[0004] The utility model is realized through the following technical solutions:

[0005] A control circuit for rapid switching of low-voltage equipment includes a main equipment control circuit and a standby equipment control circuit. The wiring terminal of the main equipment control circuit is connected to the main power supply cabinet, and the wiring terminal of the standby equipment control circuit is connected to the standby power supply cabinet;

[0006] The outgoing ends of the main equipment control circuit and the standby equipment control circuit are short-circuited in the same phase and then connected to the load;

[0007] After the terminal block of the main equipment control circuit is removed, it is connected to the normally closed point of the intermediate relay, and the normally open point of the intermediate relay is connected to the terminal of the standby equipment control circuit;

[0008] The standby equipment control circuit sequentially connects a 2P circuit breaker, a two-position switch, and an intermediate relay from the outgoing end of the standby power supply cabinet; one end of the two-position switch is connected to the L line of the 2P circuit breaker, and the other end is connected to the coil terminal of the intermediate relay; the N line terminal of the 2P circuit breaker is connected to the coil terminal of the intermediate relay.

[0009] Preferably, a main frequency converter and a secondary frequency converter are respectively arranged on the main equipment control circuit and the standby equipment control circuit;

[0010] Molded case circuit breakers a and b are respectively arranged at the output ends of the main frequency converter and the secondary frequency converter;

[0011] The outgoing terminals of molded case circuit breaker a and molded case circuit breaker b are short-circuited in the same phase and then connected to the load.

[0012] The working principle of the present utility model is as follows:

[0013] First, confirm that the control circuits of the primary and standby devices are de-energized. Then, close the control power switch of the intermediate relay, and switch the transfer switch to the control circuit of the standby device for control. At this time, all normally open points of the intermediate relay are closed, the control circuit of the standby device is powered on, the control circuit of the primary device is de-energized, and the load is powered through the control circuit of the standby device without stopping the machine. After confirming that the DCS background signal and the on-site control box signal are both normal, the smoke exhaust fan can be started. When troubleshooting the primary control circuit, isolation protection should be done at the intermediate relay position.

[0014] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0015] Through the normally open / normally closed conversion control principle of the transfer switch and the intermediate relay, the present utility model realizes the rapid switching of the primary and standby dual circuits, reduces the fault handling time, provides guarantee for the safe production of metallurgical furnaces, and greatly reduces the safety risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the control schematic diagram of the present utility model.

[0017] Figure 2 It is the connection diagram of the control circuits of the primary and standby devices.

[0018] Reference numerals: 1 - 2P circuit breaker, 2 - transfer switch, 3 - intermediate relay, 4 - main frequency converter, 5 - auxiliary frequency converter, 6 - molded case circuit breaker a, 7 - molded case circuit breaker b. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The following further describes the present utility model with reference to the drawings. In the embodiments, unless otherwise specified, the technical means used are all conventional technical means in the art. Embodiment 1

[0020] As Figure 1 shown, a control circuit for rapid switching of low-voltage devices includes a control circuit of a primary device and a control circuit of a standby device. The terminal of the control circuit of the primary device is connected to the primary power cabinet, and the terminal of the control circuit of the standby device is connected to the standby power cabinet;

[0021] As Figure 2As shown in the figure, a main frequency converter 4 and a secondary frequency converter 5 are respectively provided on the main equipment control loop and the standby equipment control loop; molded case circuit breakers a6 and b7 are respectively provided at the output ends of the main frequency converter 4 and the secondary frequency converter 5; the outgoing line ends of the molded case circuit breakers a6 and b7 are short-circuited in the same phase and then connected to the load;

[0022] After the terminal block of the main equipment control loop is removed, it is connected to the normally closed point of the intermediate relay 3, and the normally open point of the intermediate relay 3 is connected to the terminal of the standby equipment control loop;

[0023] The control loop of the standby equipment sequentially connects a 2P circuit breaker 1, a two-position switch 2, and an intermediate relay 3 from the outgoing line end of the standby power supply cabinet; one end of the two-position switch 2 is connected to the L line of the 2P circuit breaker 1, and the other end is connected to the coil terminal of the intermediate relay 3; the N line terminal of the 2P circuit breaker 1 is connected to the coil terminal of the intermediate relay 3.

[0024] The working principle of this embodiment is as follows:

[0025] First, confirm that the main and standby equipment control loops are powered off. Close the control power switch of the intermediate relay 3, and switch the switch 2 to the standby equipment control loop for control. At this time, all the normally open points of the intermediate relay 3 are closed, the standby control equipment loop is powered on, the main equipment control loop is powered off, and the load is powered by the standby equipment control loop without shutdown. After confirming that the DCS background signal and the on-site control box signal are both normal, the smoke exhaust fan can be started. When troubleshooting the main control loop, isolation protection should be done at the intermediate relay 3.

[0026] The above embodiments are only exemplary embodiments of the present invention and are not used to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent replacements should also be regarded as falling within the protection scope of the present invention.

Claims

1. A control circuit for rapid switching of low-voltage equipment, including a control circuit for the primary equipment and a control circuit for the standby equipment, characterized in that: The wiring terminal of the main equipment control circuit is connected to the main power supply cabinet, and the wiring terminal of the standby equipment control circuit is connected to the standby power supply cabinet; The outgoing line ends of the main equipment control circuit and the standby equipment control circuit are short-circuited in the same phase and then connected to the load; After the terminal block of the main equipment control circuit is removed, it is connected to the normally closed point of the intermediate relay (3), and the normally open point of the intermediate relay (3) is connected to the standby equipment control circuit terminal; The control circuit of the standby equipment is sequentially connected with a 2P circuit breaker (1), a two-position switch (2), and an intermediate relay (3) starting from the outgoing line end of the standby power supply cabinet; one end of the two-position switch (2) is connected to the L line of the 2P circuit breaker (1), and the other end is connected to the coil terminal of the intermediate relay (3); the N line terminal of the 2P circuit breaker (1) is connected to the coil terminal of the intermediate relay (3).

2. The control circuit for rapid switching of low-voltage equipment according to claim 1, characterized in that: A main frequency converter (4) and a sub-frequency converter (5) are respectively provided on the main equipment control circuit and the standby equipment control circuit; Molded case circuit breakers a (6) and molded case circuit breakers b (7) are respectively provided at the output ends of the main frequency converter (4) and the sub-frequency converter (5); The outgoing line ends of the molded case circuit breaker a (6) and the molded case circuit breaker b (7) are short-circuited in the same phase and then connected to the load.

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