Motor step-down starting loop

Abstract

The utility model discloses a motor step-down starting loop. The motor step-down starting loop comprises a main circuit, a motor starting circuit, a star connection circuit, a delay circuit, a step-down starting triangular connection circuit, a soft starting triangular connection circuit, a soft starting condition circuit and a soft starting circuit. After a star-shaped connection contactor breaks down, an original star-delta voltage reduction starting related loop is disconnected in time, so that the motor is powered off immediately, direct starting of triangular connection is prevented, and burning of the motor is avoided. And when star-triangle voltage reduction starting cannot be carried out, triangular connection of the soft starter is switched to continue operation, and continuous production is ensured.

Description

Technical field:

[0001] The utility model relates to the field of motor control circuits, in particular to a motor voltage reduction starting circuit. Background technology:

[0002] Star-delta starting is a step-down starting method for large motors, that is, when the motor is started, the motor is connected in star connection to reduce the instantaneous current of the motor starting, and the motor is changed to delta connection during normal operation to increase the motor operating power. During the star-delta starting process, the switching of the two connection methods is essentially to connect the motor stator winding into a delta or star shape through the normally open contacts of the two contactors. Since the star-connected contactor will be attracted first every time the motor is started and stopped, the running time is short. After long-term operation, the contactor coil will be damaged and cannot be discovered in time. The star connection stage will be skipped during startup, and the delta connection full-voltage start will be performed directly, resulting in the motor being unable to start and the main switch being tripped. In severe cases, the motor will be burned due to excessive load. Utility model content:

[0003] The utility model aims to provide a motor voltage reduction starting circuit.

[0004] The utility model is implemented by the following technical solutions:

[0005] A motor step-down starting circuit comprises a main circuit, a motor starting circuit, a star connection circuit, a delay circuit, a step-down starting delta connection circuit, a soft starting delta connection circuit, a soft starting condition circuit and a soft starting circuit;

[0006] The main circuit includes a normally open contact of a motor contactor and a motor connected to a power source in sequence, wherein the U1, V1, and W1 ends of the motor are respectively connected to one end of the normally open contact of the star-connected contactor, and the other end of the normally open contact of the star-connected contactor is short-circuited; the U1, V1, and W1 ends of the motor are respectively connected to one end of the normally open contact of the delta-connected contactor, and the other end of the normally open contact of the delta-connected contactor is connected to the W2, U2, and V2 ends of the motor; the normally open contact of the motor contactor is connected in parallel with a soft starter;

[0007] The motor starting circuit comprises a stop button, a start button, a normally closed contact of the second relay and a coil of the motor contactor which are connected in series in sequence to form a closed loop;

[0008] The star connection circuit comprises a normally closed contact of a second relay, a normally closed contact of a time relay and a coil of a star connection contactor which are connected in series in sequence; the star connection circuit is connected in parallel with the normally closed contact of the second relay and the coil of the motor contactor which are connected in series in the motor starting circuit; the coil of the star connection contactor is connected in parallel with the coil of the first relay;

[0009] The delay circuit comprises a time relay, and the normally closed contact of the time relay and the coil of the first relay are connected in series and then connected in parallel with the delay circuit;

[0010] The step-down starting delta connection circuit comprises a normally closed contact of the star connection contactor, a normally open contact of the time delay relay and a coil of the delta connection contactor; the delta connection loop is connected in parallel with the star connection circuit;

[0011] The soft-start delta connection circuit is composed of a normally open contact loop of a third relay; the soft-start delta connection circuit is connected in series with the coil of the delta connection contactor in the step-down starting delta connection circuit to form a closed loop;

[0012] The soft start condition circuit comprises a normally open contact of a first relay, a normally closed contact of a star connection contactor and a coil of a second relay which are sequentially connected in series to form a closed loop;

[0013] The soft start circuit comprises a normally open contact of a second relay and a coil of a third relay which are sequentially connected in series to form a closed loop;

[0014] The RUN end of the soft starter is connected in series with a normally open contact of a delta connection contactor and a normally open contact of a second relay to form a closed loop; the STOP end of the soft starter is connected in series with a soft start stop button to form a closed loop.

[0015] Preferably, it also includes a star connection normal indication circuit and a star connection abnormal indication circuit;

[0016] The star connection normal indication circuit comprises a normally open contact of a star connection contactor and a star connection normal indicator light connected in series, and the star connection normal indication circuit is connected in series with the normally open contact of the first relay in the soft start condition circuit to form a closed circuit;

[0017] The star connection abnormality indication circuit includes a star connection abnormality indicator light, and the star connection abnormality indication circuit is connected in parallel with the coil of the second relay in the soft start condition circuit.

[0018] Preferably, in the motor starting circuit, both ends of the start button are connected in parallel with a normally open contact of a motor contactor;

[0019] Two ends of the normally open contacts of the second relay in the soft start circuit are connected in parallel with a normally open contact of a third relay;

[0020] A step-down starting self-locking circuit is connected in parallel at both ends of the normally open contacts of the time delay relay of the step-down starting delta connection circuit. The step-down starting self-locking circuit includes a normally open contact of a delta connection contactor and a normally closed contact of a third relay connected in series.

[0021] The utility model has the advantages that after a star-connected contactor fails, the original star-delta step-down starting-related circuit is disconnected in time, so that the motor is immediately powered off, and direct starting with a delta connection is prevented, thereby avoiding burning of the motor; when star-delta step-down starting is not possible, the soft starter is switched to a delta connection to continue operation, ensuring continued production. Description of the drawings:

[0022] Figure 1 It is a schematic diagram of the main circuit of the utility model;

[0023] Figure 2 It is a schematic diagram of a control circuit of the utility model.

[0024] In the figure: motor M, motor contactor KM1, delta connection contactor KM2, star connection contactor KM3, stop button SB1, start button SB2, soft start stop button SB3, first relay KA1, second relay KA2, third relay KA3, delay relay KT, star connection normal indicator light HL1, star connection abnormal indicator light HL2, thermal relay FR. Specific implementation method:

[0025] like Figure 1 and Figure 2 As shown, a motor step-down starting circuit includes a main circuit, a motor starting circuit, a star connection circuit, a delay circuit, a step-down starting delta connection circuit, a soft starting delta connection circuit, a soft starting condition circuit and a soft starting circuit;

[0026] The main circuit includes the normally open contact of the motor contactor KM1 and the motor M which are connected to the power supply in sequence. The U1, V1 and W1 ends of the motor M are respectively connected to one end of the normally open contact of the star connection contactor KM3, and the other end of the normally open contact of the star connection contactor KM3 is short-circuited; the U1, V1 and W1 ends of the motor M are respectively connected to one end of the normally open contact of the delta connection contactor KM2, and the other end of the normally open contact of the delta connection contactor KM2 is connected to the W2, U2 and V2 ends of the motor M; the normally open contact of the motor contactor KM1 is connected in parallel with the soft starter;

[0027] The motor starting circuit includes a stop button SB1, a start button SB2, a normally closed contact of the second relay KA2 and a coil of the motor contactor KM1 which are connected in series to form a closed loop. A normally open contact of the motor contactor KM1 is connected in parallel at both ends of the start button SB2 of the motor starting circuit to form a self-locking function. A thermal relay FR protection circuit is installed in the motor starting circuit.

[0028] The star connection circuit includes a normally closed contact of the second relay KA2, a normally closed contact of the time relay and the coil of the star connection contactor KM3 which are connected in series in sequence; the star connection circuit is connected in parallel with the normally closed contact of the second relay KA2 and the coil of the motor contactor KM1 which are connected in series in the motor starting circuit; the coil of the star connection contactor KM3 is connected in parallel with the coil of the first relay KA1;

[0029] The delay circuit includes a time relay, and the normally closed contact of the time relay and the coil of the first relay KA1 are connected in series and then in parallel with the delay circuit;

[0030] The step-down starting delta connection circuit includes a normally closed contact of the star connection contactor KM3, a normally open contact of the time delay relay KT, and a coil of the delta connection contactor KM2; the delta connection circuit is connected in parallel with the star connection circuit, and a step-down starting self-locking circuit is connected in parallel at both ends of the normally open contact of the time delay relay KT of the step-down starting delta connection circuit, and the step-down starting self-locking circuit includes a normally open contact of the delta connection contactor KM2 and a normally closed contact of the third relay KA3 connected in series;

[0031] The soft-start delta connection circuit is composed of a normally open contact circuit of a third relay KA3; the soft-start delta connection circuit is connected in series with the coil of the delta connection contactor KM2 in the step-down starting delta connection circuit to form a closed circuit;

[0032] The soft start condition circuit includes a normally open contact of a first relay KA1, a normally closed contact of a star connection contactor KM3 and a coil of a second relay KA2 which are connected in series to form a closed loop;

[0033] The soft start circuit includes a normally open contact of a second relay KA2 and a coil of a third relay KA3 which are connected in series to form a closed loop. A normally open contact of the third relay KA3 is connected in parallel at both ends of the normally open contact of the second relay KA2 in the soft start circuit to form a self-locking;

[0034] The RUN terminal of the soft starter is connected in series with the normally open contact of a delta connection contactor KM2 and the normally open contact of a second relay KA2 to form a closed loop; the STOP terminal of the soft starter is connected in series with the soft start stop button SB3 to form a closed loop;

[0035] During normal operation:

[0036] Press the start button SB2, the coils of the motor contactor KM1, the star connection contactor KM3, the first relay KA1 and the delay relay KT are energized, the normally open contacts of the motor contactor KM1 and the star connection contactor KM3 in the main circuit are closed, the stator of the motor M is star-connected, and the motor M is started in star connection. At this time, the normally open contact of the motor contactor KM1 connected in parallel with the start button SB2 is closed to form a self-locking. This process is a star connection start; after running for a period of time, the normally open contact of the delay relay KT is closed, and the normally closed contact is disconnected, that is, the star connection circuit The normally closed contact of the middle delay relay KT is disconnected, the star connection circuit is disconnected, the coil of the star connection contactor KM3 loses power, the normally open contact of the star connection contactor KM3 in the main circuit is disconnected, and at the same time, the normally open contact of the delay relay KT in the step-down starting delta connection circuit is closed, the step-down starting delta connection circuit is connected, the coil of the delta connection contactor KM2 is energized, the normally open contact of the delta connection contactor KM2 in the main circuit is closed, and the connection mode of the motor M is switched from star connection to delta connection; after the delta connection, the motor M operates normally and the equipment starts successfully;

[0037] When shutting down, just press the stop button SB1, the motor starting circuit will be disconnected, the motor contactor KM1 coil will lose power, the motor M will stop running, and the other related circuits will be disconnected together.

[0038] In case of a fault in the star connection contactor KM3:

[0039] When the start button SB2 is pressed, the coils of the motor contactor KM1, the star connection contactor KM3, the first relay KA1 and the delay relay KT are energized, and the normally open contact of the first relay KA1 in the soft start condition circuit is closed, while the star connection contactor KM3 that should have been energized is not energized. At this time, the soft start condition circuit is connected, the coil of the second relay KA2 is energized, the normally open contact of the second relay KA2 in the soft start circuit is closed, the normally closed contact of the second relay KA2 in the motor start circuit is disconnected, the motor start circuit is disconnected, and the corresponding motor start circuit, star connection circuit, delay circuit and step-down start delta connection circuit are all disconnected; and the soft start circuit is connected, the relay of the third relay KA3 is energized, and is connected to the normally open contact of the second relay KA2 in the soft start circuit. The normally open contact of the third relay KA3 with parallel contacts is closed to form a self-locking state; the normally open contact of the third relay KA3 in the soft start delta connection circuit is closed, the soft start delta connection circuit is connected, the coil of the delta connection contactor KM2 is energized, the normally closed contact of the delta connection contactor KM2 in the main circuit is closed, and the motor M is connected in a delta shape; and at the moment when the second relay KA2 and the delta connection contactor KM2 are energized, the normally closed contact of the delta connection contactor KM2 at the RUN end of the soft starter is disconnected, and the normally open contact of the second relay KA2 is closed, so the RUN end of the soft starter will instantly input a high level, the soft starter intervenes, and the motor M is started by the soft starter; when shutting down, press the soft start stop button SB3, the STOP input of the soft starter is high, and the soft starter is cut off.

[0040] It also includes a star connection normal indication circuit and a star connection abnormal indication circuit;

[0041] The star connection normal indication circuit includes a normally open contact of the star connection contactor KM3 and the star connection normal indicator light HL1 connected in series. The star connection normal indication circuit is connected in series with the normally open contact of the first relay KA1 in the soft start condition circuit to form a closed circuit. In use, when the star connection circuit is connected, if the star connection contactor KM3 is normal, the normally open contact of the star connection contactor KM3 in the star connection normal indication circuit will be closed, the star connection normal indication circuit will be connected, and the star connection normal indicator light HL1 will light up.

[0042] The star connection abnormality indication circuit includes the star connection abnormality indicator light HL2. The star connection abnormality indication circuit is connected in parallel with the coil of the second relay KA2 in the soft start condition circuit. If the star connection contactor KM3 fails, the normally open contact of the star connection contactor KM3 in the star connection normal indication circuit of the soft start circuit will be closed, the star connection normal indication circuit will be connected, and the star connection normal indicator light HL1 will light up.

[0043] 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 motor step-down starting circuit, characterized in that: It includes a main circuit, a motor starting circuit, a star connection circuit, a delay circuit, a step-down starting delta connection circuit, a soft starting delta connection circuit, a soft starting condition circuit and a soft starting circuit; The main circuit includes a normally open contact of a motor contactor and a motor connected to a power source in sequence, wherein the U1, V1, and W1 ends of the motor are respectively connected to one end of the normally open contact of the star-connected contactor, and the other end of the normally open contact of the star-connected contactor is short-circuited; the U1, V1, and W1 ends of the motor are respectively connected to one end of the normally open contact of the delta-connected contactor, and the other end of the normally open contact of the delta-connected contactor is connected to the W2, U2, and V2 ends of the motor; the normally open contact of the motor contactor is connected in parallel with a soft starter; The motor starting circuit comprises a stop button, a start button, a normally closed contact of the second relay and a coil of the motor contactor which are connected in series in sequence to form a closed loop; The star connection circuit comprises a normally closed contact of a second relay, a normally closed contact of a time relay and a coil of a star connection contactor which are connected in series in sequence; the star connection circuit is connected in parallel with the normally closed contact of the second relay and the coil of the motor contactor which are connected in series in the motor starting circuit; the coil of the star connection contactor is connected in parallel with the coil of the first relay; The delay circuit comprises a time relay, and the normally closed contact of the time relay and the coil of the first relay are connected in series and then connected in parallel with the delay circuit; The step-down starting delta connection circuit comprises a normally closed contact of the star connection contactor, a normally open contact of the time delay relay and a coil of the delta connection contactor; the delta connection loop is connected in parallel with the star connection circuit; The soft-start delta connection circuit is composed of a normally open contact loop of a third relay; the soft-start delta connection circuit is connected in series with the coil of the delta connection contactor in the step-down starting delta connection circuit to form a closed loop; The soft start condition circuit comprises a normally open contact of a first relay, a normally closed contact of a star connection contactor and a coil of a second relay which are sequentially connected in series to form a closed loop; The soft start circuit comprises a normally open contact of a second relay and a coil of a third relay which are sequentially connected in series to form a closed loop; The RUN end of the soft starter is connected in series with a normally open contact of a delta connection contactor and a normally open contact of a second relay to form a closed loop; the STOP end of the soft starter is connected in series with a soft start stop button to form a closed loop.

2. A motor step-down starting circuit according to claim 1, characterized in that: It also includes a star connection normal indication circuit and a star connection abnormal indication circuit; The star connection normal indication circuit comprises a normally open contact of a star connection contactor and a star connection normal indicator light connected in series, and the star connection normal indication circuit is connected in series with the normally open contact of the first relay in the soft start condition circuit to form a closed circuit; The star connection abnormality indication circuit includes a star connection abnormality indicator light, and the star connection abnormality indication circuit is connected in parallel with the coil of the second relay in the soft start condition circuit.

3. A motor step-down starting circuit according to claim 1 or 2, characterized in that: In the motor starting circuit, two ends of the start button are connected in parallel with a normally open contact of a motor contactor; Two ends of the normally open contacts of the second relay in the soft start circuit are connected in parallel with a normally open contact of a third relay; A step-down starting self-locking circuit is connected in parallel at both ends of the normally open contacts of the time delay relay of the step-down starting delta connection circuit. The step-down starting self-locking circuit includes a normally open contact of a delta connection contactor and a normally closed contact of a third relay connected in series.

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