Control circuit for cold-state operation of soft starter after starting of motor

Abstract

The utility model discloses a control circuit for cold-state operation of a soft starter after a motor is started, and relates to the technical field of electrical control. According to the utility model, through improvement of a traditional soft start control circuit, after a contactor bypass in a starting stage of the soft starter is completed, the soft starter can control voltage to be cut off through disconnection of a bypass contactor auxiliary normally-closed point, and in addition, a self-locking function is realized through a bypass contactor normally-open auxiliary point, so that a bypass contactor coil is kept to be electrified continuously; the control panel of the soft starter is in a cold-state no-power state, so that the problems that the soft starter is shut down due to malfunction and electrified elements are aged for a long time in the equipment operation process are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of electrical control, in particular to a control circuit for a soft starter to run in cold state after a motor is started. Background Art

[0002] With the development of electronic technology, thyristor solid-state soft starters are widely used. The reliability and service life of solid-state thyristor soft starters are important factors related to the continuous and stable operation of equipment. The main function of solid-state thyristors is to achieve smooth starting of the motor when the motor starts. After the motor reaches full speed, it is bypassed by the contactor and has no substantial effect on the normal operation of the motor. However, in actual use, the soft start control board is still involved in the self-holding control of the contactor coil of the motor control circuit. As a result, the soft start control device will be powered on for a long time in industrial production, which will accelerate the aging of the soft start electronic components and shorten the service life of the soft start. Utility Model Content

[0003] In view of the above technical problems, the utility model provides a control circuit for cold operation of a soft starter after motor start-up, which is used to solve the problem that the soft start control device runs with power for a long time in industrial production after motor start-up, which accelerates the aging of soft start electronic components and shortens the service life of the soft starter.

[0004] In order to achieve the above purpose, the technical solution of the utility model is as follows:

[0005] A control circuit for cold operation of a soft starter after motor starting, comprising a three-phase power supply, power phase lines L1, L2, and L3 of the three-phase power supply are connected to upper wiring terminals of a three-phase circuit breaker, the three-phase lower wiring terminals of the three-phase circuit breaker are connected in series with the three-phase input terminals of the soft starter, the three-phase normally open main contacts of a bypass contactor are connected in parallel to the three-phase input terminal of the soft starter, the three-phase lower terminals of the three-phase normally open main contacts of the bypass contactor are connected in series with the three-phase thermal element of a thermal protection relay, the other end of the three-phase thermal element of the thermal protection relay is connected to the three-phase output terminal of the soft starter and connected to the three-phase asynchronous motor, the power phase line of the three-phase power supply L3 is connected in series with a fuse, the other end of the fuse is connected to the shutdown normally open contactor, and the three-phase normally open main contacts of the bypass contactor are connected in series with the three-phase normally open main contacts of the three-phase circuit breaker. The soft starter connects one end of the common terminal E and the start input terminal Q in series with the normally open start button, and the common terminal E and the stop input terminal S are short-circuited by a wire; the working power supply L of the soft starter is connected in series with the auxiliary normally closed point of the bypass contactor, and the working power supply N of the soft starter is connected to the power neutral line as required.

[0006] Compared with the prior art, the utility model has the following beneficial effects: the utility model improves the traditional soft start control circuit. After the soft starter completes the contactor bypass in the startup phase, the soft starter control voltage can be cut off by disconnecting the auxiliary normally closed point of the bypass contactor. In addition, the self-locking function is realized by the normally open auxiliary point of the bypass contactor to keep the bypass contactor coil energized, so that the soft starter control board is in a cold and power-free state, thus solving the problems of malfunction and shutdown of the soft starter during equipment operation and aging of long-term live components. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a circuit schematic diagram of the utility model. Description of the drawings:

[0009] 1. Three-phase circuit breaker; 2. Soft starter; 3. Three-phase normally open main contact of bypass contactor; 4. Three-phase thermal element of thermal protection relay; 5. Three-phase asynchronous motor; 6. Fuse; 7. Normally closed button for shutdown; 8. Auxiliary normally open point of bypass contactor; 9. Normally open point for start and stop of soft starter; 10. Normally closed point of thermal relay; 11. Bypass contactor coil; 12. Normally open start button; 13. Auxiliary normally closed point of bypass contactor. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is further described in detail below in combination with specific implementation methods and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the utility model. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the utility model.

[0011] A control circuit for cold operation of a soft starter after a motor is started, comprising a three-phase power supply, wherein power phase lines L1, L2 and L3 of the three-phase power supply are connected to the upper wiring terminal of a three-phase circuit breaker 1, and the three-phase lower wiring terminals of the three-phase circuit breaker 1 are connected in series with the three-phase input terminals of a soft starter 2. At the same time, a three-phase normally open main contact 3 of a bypass contactor is connected in parallel to the three-phase input terminal of the soft starter 2, and the three-phase lower terminals of the three-phase normally open main contact 3 of the bypass contactor are connected in series with a three-phase thermal element 4 of a thermal protection relay, and the other end of the three-phase thermal element 4 of the thermal protection relay is connected to the three-phase output terminal of the soft starter 2 and connected to a three-phase asynchronous motor 5, and a power phase line of the three-phase power supply L3 is connected in series with a fuse 6, and the other end of the fuse 6 is connected to one end of a normally closed button 7 for shutdown. , the other end of the shutdown normally closed button 7 is connected to one end of the soft starter start and stop normally open point 9, and is connected to one end of the bypass contactor auxiliary normally open point 8. The other end of the soft starter start and stop normally open point 9 is connected in parallel with one end of the bypass contactor auxiliary normally open point 8, and is connected in series to one end of the thermal relay normally closed point 10. The other end of the thermal relay normally closed point 10 is connected to one end of the bypass contactor coil 11, and the other end of the bypass contactor coil 11 is connected to the power supply N neutral line. In addition, the common terminal E and the start input terminal Q of the soft starter 2 are connected in series to the normally open start button 12, and the common terminal E and the stop input terminal S are connected in series to the normally closed button and are directly short-circuited with a wire; the working power supply L of the soft starter 2 is connected in series with the bypass contactor auxiliary normally closed point 13, and the working power supply N of the soft starter 2 is connected to the power supply neutral line as required.

[0012] During operation, after closing the three-phase circuit breaker 1, press the normally open start button 12, such as the soft starter 2 starts to work (the input voltage of the soft starter 2 is gradually increased to full voltage by controlling the conduction angle, and the three-phase asynchronous motor 5 runs at full speed), the three-phase asynchronous motor 5 gradually runs at full speed through the soft starter 2, and the soft starter start-stop normally open point 9 is closed, so that the bypass contactor coil 11 forms a path through the terminal L, the fuse 6, the shutdown normally closed button 7, the soft starter start-stop normally open point 9, the thermal relay normally closed point 10, the bypass contactor coil 11 and the power supply N terminal, the bypass contactor coil 11 is energized and attracted, and the bypass contactor three-phase normally open main contact 3 is connected, and the main circuit of the soft starter 2 is bypassed and short-circuited; the bypass contactor auxiliary normally open point 8 is closed to complete the energized self-locking function of the contactor, and the bypass contactor auxiliary normally closed point 13 is disconnected, so that the soft starter 2 The control voltage loses pressure, so that the control circuit of the soft starter 2 is in a cold running state. When the shutdown normally closed button 7 is pressed, the branch of the bypass contactor coil 11 is disconnected, the bypass contactor coil 11 loses power, and the motor stops while the bypass contactor auxiliary normally closed point 13 is restored to be connected, the soft starter 2 control power supply L is connected, and the soft starter 2 is in a ready-to-start state again. Through the improvement of the traditional soft starter control circuit, after the soft starter 2 completes the contactor bypass in the startup phase, the control voltage of the soft starter 2 can be cut off by disconnecting the bypass contactor auxiliary normally closed point 13. In addition, through the bypass contactor auxiliary normally open point 8, the self-locking function is realized to keep the bypass contactor coil 11 powered on, so that the control board of the soft starter 2 is in a cold and power-free state, which solves the problem of malfunction shutdown of the soft starter during equipment operation and aging of long-term live components.

[0013] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A control circuit for cold operation of a soft starter after a motor is started, characterized in that: The invention comprises a three-phase power supply, wherein power phase lines L1, L2 and L3 of the three-phase power supply are connected to the upper wiring terminal of a three-phase circuit breaker (1), the three-phase lower wiring terminals of the three-phase circuit breaker (1) are connected in series with the three-phase input terminals of a soft starter (2), the three-phase normally open main contact (3) of a bypass contactor is connected in parallel to the three-phase input terminal of the soft starter (2), the three-phase lower terminals of the three-phase normally open main contact (3) of the bypass contactor are connected in series with the three-phase thermal element (4) of a thermal protection relay, the other end of the three-phase thermal element (4) of the thermal protection relay is connected to the three-phase output terminal of the soft starter (2) and connected to a three-phase asynchronous motor (5), the power phase line of the three-phase power supply L3 is connected in series with a fuse (6), the other end of the fuse (6) is connected to one end of a normally closed stop button (7), and the normally closed stop button (7) The other end is connected to one end of the soft starter start / stop normally open point (9), and is connected to one end of the bypass contactor auxiliary normally open point (8). The other end of the soft starter start / stop normally open point (9) is connected in parallel with one end of the bypass contactor auxiliary normally open point (8), and is connected in series to one end of the thermal relay normally closed point (10). The other end of the thermal relay normally closed point (10) is connected to one end of the bypass contactor coil (11). The other end of the bypass contactor coil (11) is connected to the power supply N neutral line. The soft starter (2) connects the common terminal E and the start input terminal Q in series to the normally open start button (12), and the common terminal E and the stop input terminal S are short-circuited through a wire. The working power supply L of the soft starter (2) is connected in series to the bypass contactor auxiliary normally closed point (13). The working power supply N of the soft starter (2) is connected to the power supply neutral line as required.

Images