Motor positive and negative rotation control circuit for preventing interphase short circuit

Abstract

The utility model discloses a motor forward and reverse rotation control circuit capable of preventing interphase short circuit. The motor forward and reverse rotation control circuit comprises a master control switch QF1, a stop button SB1, a forward rotation start button SB2, a reverse rotation start button SB3, a forward rotation contactor KM1, a reverse rotation contactor KM2, a time relay KT, a first relay KA, a start permission indication lamp HL1 and a start dispermission indication lamp HL2. Through mutual cooperation of a stop button SB1, a time relay KT and a start-not-allowed indicating lamp HL2, a set time interval exists between stopping of the motor and restarting of the motor, and through lighting of the start-not-allowed indicating lamp HL2, it is clearly indicated that a forward rotation start button SB2 or a reverse rotation start button SB3 is forbidden to be pressed down, so that the situation that forward rotation of the motor is not completely stopped, and the motor cannot be started again is avoided. When the motor rotates, the motor rotates reversely, or the motor rotates forwards if the reverse rotation is not stopped completely, and when the rotating direction of the motor is switched, the set time of the time relay KT can ensure that the motor is stopped completely, so that the problem of inter-phase short circuit is avoided, and safe production is ensured.

Description

Technical Field:

[0001] The utility model relates to the technical field of motor control, and particularly relates to a forward and reverse rotation control circuit of a motor for preventing phase-to-phase short circuit. Background Art:

[0002] In manufacturing enterprises, due to the requirements of production processes, some motors are in a working mode of frequent forward and reverse rotation for a long time. During the operation process, it often occurs that the motor starts to reverse before it completely stops in the forward rotation, or starts to rotate forward before it completely stops in the reverse rotation. This has a relatively large impact on the motor and is prone to cause phase-to-phase short circuit. If the motor is not fixed firmly and the anchor bolts become loose, it will lead to line faults or motor burnout problems. Content of the Utility Model:

[0003] The purpose of the utility model is to provide a forward and reverse rotation control circuit of a motor for preventing phase-to-phase short circuit.

[0004] The purpose of the utility model is implemented by the following technical solution: A forward and reverse rotation control circuit of a motor for preventing phase-to-phase short circuit, which includes a main control switch QF1, a stop button SB1, a forward rotation start button SB2, a reverse rotation start button SB3, a forward rotation contactor KM1, a reverse rotation contactor KM2, a time relay KT, a first relay KA, an allow start indicator light HL1, and a non-allow start indicator light HL2;

[0005] The forward rotation start button SB2, the normally closed contact of the reverse rotation contactor KM2, and the forward rotation contactor KM1 coil are connected in series to form a first control circuit, and the forward rotation start button SB2 is connected in parallel with the normally open contact of the forward rotation contactor KM1; the reverse rotation start button SB3, the normally closed contact of the forward rotation contactor KM1, and the reverse rotation contactor KM2 coil are connected in series to form a second control circuit, and the reverse rotation start button SB3 is connected in parallel with the normally open contact of the reverse rotation contactor KM2; after the first control circuit, the second control circuit, and the allow start indicator light HL1 are connected in parallel, they are connected in series with the main control switch QF1, the normally closed contact of the stop button SB1, and the normally closed contact of the first relay KA to form a closed loop;

[0006] The normally open contact of the stop button SB1, the normally closed contact with delayed disconnection of the time relay KT, and the first relay KA coil are connected in series to form a third control circuit, the normally open contact of the first relay KA and the time relay KT coil are connected in series to form a fourth control circuit. After the normally closed contact with delayed disconnection of the time relay KT and the first relay KA coil are connected in series, they are connected in parallel with the non-allow start indicator light HL2 and the time relay KT coil; after the third control circuit and the fourth control circuit are connected in parallel, they are connected in series with the main control switch QF1 to form a closed loop.

[0007] Preferably, an auxiliary normally-closed contact of a thermal relay FR is connected in series between the main control switch QF1 and the normally-closed contact of the stop button SB1, and after the third control line and the fourth control line are connected in parallel, they are connected in series with the auxiliary normally-closed contact of the thermal relay FR.

[0008] Advantages of the present utility model: According to the actual production requirements on site, by setting the stop button SB1, the time relay KT, and the non-start allowable indicator light HL2 to cooperate with each other, a set time interval exists between the motor stop and the motor restart, and by turning on the non-start allowable indicator light HL2, it clearly indicates that it is prohibited to press the forward start button SB2 or the reverse start button SB3, avoiding the situation where the motor starts to reverse before it has completely stopped in the forward direction, or starts to rotate forward before it has completely stopped in the reverse direction. When switching the rotation direction of the motor, the set time of the time relay KT can ensure that the motor completely stops, avoiding the problem of interphase short circuit and ensuring safe production. Description of the drawings:

[0009] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following-described drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative labor, other drawings can also be obtained based on these drawings.

[0010] Figure 1 is the circuit diagram of the present utility model.

[0011] Figure 2 is the circuit diagram of the main circuit controlled by the present utility model.

[0012] The markings of each component in the drawings are as follows: main control switch QF1, stop button SB1, forward start button SB2, reverse start button SB3, forward contactor KM1, reverse contactor KM2, time relay KT, first relay KA, start allowable indicator light HL1, non-start allowable indicator light HL2, main switch QF, thermal relay FR, motor M3, first control line 1, second control line 2, third control line 3, fourth control line 4. Detailed implementation manners:

[0013] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0014] As Figure 1 - Figure 2 shown, a forward and reverse control circuit for a motor to prevent phase-to-phase short circuit includes a main control switch QF1, a stop button SB1, a forward start button SB2, a reverse start button SB3, a forward contactor KM1, a reverse contactor KM2, a time relay KT, a first relay KA, an allow start indicator light HL1, and a non-allow start indicator light HL2; the main circuit controlled by the present invention is of an existing structure, which includes a main switch QF, normally open contacts of the forward contactor KM1, normally open contacts of the reverse contactor KM2, a thermal relay FR, and a motor M3. The three-phase power supply lines of the motor M3 are sequentially connected in series to the main switch QF, the normally open contacts of the forward contactor KM1, and the thermal relay FR and then connected to the motor M3. The normally open contacts of the reverse contactor KM2 are connected in phase change at both ends of the normally open contacts of the forward contactor KM1 to form the main circuit controlled by the present invention.

[0015] The forward start button SB2, the normally closed contact of the reverse contactor KM2, and the forward contactor KM1 coil are connected in series to form a first control circuit 1, and the forward start button SB2 is connected in parallel with the normally open contact of the forward contactor KM1.

[0016] The reverse start button SB3, the normally closed contact of the forward contactor KM1, and the reverse contactor KM2 coil are connected in series to form a second control circuit 2, and the reverse start button SB3 is connected in parallel with the normally open contact of the reverse contactor KM2.

[0017] After the first control circuit 1, the second control circuit 2, and the allow start indicator light HL1 are connected in parallel, they are connected in series with the main control switch QF1, the auxiliary normally closed contact of the thermal relay FR, the normally closed contact of the stop button SB1, and the normally closed contact of the first relay KA to form a closed loop. When the allow start indicator light HL1 is on, it is allowed to press the forward start button SB2 or the reverse start button SB3.

[0018] The normally open contact of the stop button SB1, the normally closed contact of the time relay KT that is delayed to open, and the coil of the first relay KA are connected in series to form the third control circuit 3. The normally open contact of the first relay KA and the coil of the time relay KT are connected in series to form the fourth control circuit 4. After the normally closed contact of the time relay KT that is delayed to open and the coil of the first relay KA are connected in series, they are connected in parallel with the no-start indicator light HL2 and the coil of the time relay KT. When the no-start indicator light HL2 is on, pressing the forward start button SB2 or the reverse start button SB3 is prohibited; after the third control circuit 3 and the fourth control circuit 4 are connected in parallel, they are connected in series with the main control switch QF1 and the auxiliary normally closed contact of the thermal relay FR to form a closed loop.

[0019] Working principle: First, close the main control switch QF1, and the start-allowed indicator light HL1 is on, indicating that it is allowed to press the forward start button SB2 or the reverse start button SB3;

[0020] Second, when the forward start button SB2 is pressed, the first control circuit 1 is instantaneously connected, the coil of the forward contactor KM1 is energized and attracted, and the normally open contact of the forward contactor KM1 is closed to form self-locking, and the motor M3 runs forward; even if the forward start button SB2 is released, due to the self-locking of the forward contactor KM1, the motor M3 still runs forward;

[0021] Third, press the stop button SB1, the coil of the forward contactor KM1 loses power, the motor M3 stops running forward, and the start-allowed indicator light HL1 goes out; at the same time, the normally open contact of the stop button SB1 is instantaneously closed, the third control circuit 3 is instantaneously connected, the coil of the first relay KA is energized and attracted, and the normally open contact of the first relay KA is attracted to form self-locking, so that the fourth control circuit 4 is connected, the coil of the time relay KT is energized and starts timing. At the same time, the no-start indicator light HL2 is on, indicating that pressing the forward start button SB2 or the reverse start button SB3 is prohibited; even if the stop button SB1 is released, due to the self-locking of the first relay KA, the coil of the time relay KT still remains energized and timing; at the same time, the normally closed contact of the first relay KA is disconnected, and the start-allowed indicator light HL1 still remains off;

[0022] When the time relay KT reaches the set time, the normally closed contact of the time relay KT that is delayed to open is disconnected, cutting off the third control circuit 3, the coil of the first relay KA loses power, the already closed normally open contact of the first relay KA is disconnected, the no-start indicator light HL2 goes out, and the already disconnected normally closed contact of the first relay KA is closed, and the start-allowed indicator light HL1 is on, indicating that it is allowed to press the forward start button SB2 or the reverse start button SB3 again;

[0023] Fourth, when the reverse start button SB3 is pressed, the second control circuit 2 is instantaneously connected, the coil of the reverse contactor KM2 is energized and attracted, and the normally open contact of the reverse contactor KM2 is closed to form self-locking, and the motor M3 runs in reverse; even if the reverse start button SB3 is released, due to the self-locking of the reverse contactor KM2, the motor M3 still runs in reverse;

[0024] Fifth, when the stop button SB1 is pressed, similarly, the coil of the reverse contactor KM2 loses power, the motor M3 stops reversing, and the allow start indicator light HL1 goes out; at the same time, the normally open contact of the stop button SB1 is instantaneously closed, the third control circuit 3 is instantaneously connected, the coil of the first relay KA is energized and attracted, and the normally open contact of the first relay KA is closed to form self-locking, so that the fourth control circuit 4 is connected, the coil of the time relay KT is energized to start timing, and at the same time, the not allow start indicator light HL2 is on, indicating that it is prohibited to press the forward start button SB2 or the reverse start button SB3 at this time; even if the stop button SB1 is released, due to the self-locking of the first relay KA, the coil of the time relay KT is still energized and timing; at the same time, the normally closed contact of the first relay KA is disconnected, and the allow start indicator light HL1 still remains off;

[0025] When the time relay KT reaches the set time, the normally closed delay-disconnecting contact of the time relay KT is disconnected, cutting off the third control circuit 3, the coil of the first relay KA loses power, the already closed normally open contact of the first relay KA is disconnected, the not allow start indicator light HL2 goes out, the already disconnected normally closed contact of the first relay KA is closed, and the allow start indicator light HL1 is on, completing a forward and reverse switching of the motor M3.

[0026] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A motor forward and reverse control circuit for preventing interphase short circuit, characterized in that: It includes a main control switch QF1, a stop button SB1, a forward start button SB2, a reverse start button SB3, a forward contactor KM1, a reverse contactor KM2, a time relay KT, a first relay KA, a start permission indicator light HL1 and a start not allowed indicator light HL2; The forward start button SB2, the normally closed contact of the reverse contactor KM2, and the coil of the forward contactor KM1 are connected in series to form a first control circuit, and the forward start button SB2 is connected in parallel with the normally open contact of the forward contactor KM1; the reverse start button SB3, the normally closed contact of the forward contactor KM1, and the coil of the reverse contactor KM2 are connected in series to form a second control circuit, and the reverse start button SB3 is connected in parallel with the normally open contact of the reverse contactor KM2; The first control circuit, the second control circuit, and the start permission indicator light HL1 are connected in parallel and then connected in series with the main control switch QF1, the normally closed contact of the stop button SB1, and the normally closed contact of the first relay KA to form a closed loop; The normally open contact of the stop button SB1, the delayed-off normally closed contact of the time relay KT, and the coil of the first relay KA are connected in series to form a third control circuit, the normally open contact of the first relay KA and the coil of the time relay KT are connected in series to form a fourth control circuit, the delayed-off normally closed contact of the time relay KT and the coil of the first relay KA are connected in series and then connected in parallel with the start-not-allowed indicator light HL2 and the coil of the time relay KT; after the third control circuit and the fourth control circuit are connected in parallel, they are connected in series with the main control switch QF1 to form a closed loop.

2. A motor forward and reverse rotation control circuit for preventing interphase short circuit according to claim 1, characterized in that: An auxiliary normally closed contact of a thermal relay FR is connected in series between the main control switch QF1 and the normally closed contact of the stop button SB1, and after the third control circuit and the fourth control circuit are connected in parallel, they are connected in series with the auxiliary normally closed contact of the thermal relay FR.

Images