Basic structure of interlocking start-stop control circuit for two three-phase AC motors

The control circuit of two three-phase AC motor interlocking refers to the control circuit in which two or more motors in the circuit start sequentially and stop in reverse order. In the circuit, the start sequence and stop sequence of the motors are controlled by the control buttons.

Basic structure of interlocking start-stop control circuit for two three-phase AC motors

1. Turn on the main power switch QS and press the start button SB2.

2. The coil of AC contactor KM1 is energized and the corresponding contacts operate.

The 2-1 moving-close auxiliary contact KM1-1 is connected to realize the self-locking function.

The 2-2 moving main contact KM1-2 is connected, and the motor M1 starts to run.

The normally closed auxiliary contacts KM1-3 are connected to prepare for the start of the motor M2. It is also used to prevent the contactor KM2 coil from being energized first, causing the motor M2 to run first, thus playing the role of sequential start.

3. When the motor M2 needs to be started, press the start button SB3. The coil of the AC contactor KM2 is energized.

The 3-1 moving-close auxiliary contact KM2-1 is connected to realize the self-locking function.

3-2 The main contact KM2-2 is connected, and the motor M2 starts to run.

3-3 The normally closed auxiliary contact KM2-3 is connected, locking the stop button SB1 to prevent the stop button SB1 of the motor M1 from being pressed when the motor M2 is started, thereby shutting down the motor M1 and achieving the reverse sequence shutdown effect.

The PLC control circuit for interlocking start and stop of two three-phase AC motors refers to the control of starting and stopping the two motors in sequence and in reverse order through the cooperation of PLC and external electrical components.

PLC-based control of two three-phase AC motors starting and stopping

1. Sequential starting process of two three-phase AC motors

The process of using Mitsubishi FX2N series PLC to control the sequential starting of two three-phase AC motors:

Close the main power switch QS, press the start button SB2 of motor M1, and set the input relay make contact X2 in the PLC program to "1", that is, the make contact X2 is closed, the output relay Y0 coil is energized, and its self-locking make contact Y0 is closed to achieve self-locking; at the same time, the make contact Y0 of the output relay Y1 is controlled to close, preparing for Y1 to be energized; the PLC external AC contactor KM1 coil is energized, the main contact KM1-1 in the main circuit is closed, the power of motor M1 is turned on, and M1 starts to run.

When the start button SB4 of motor M2 is pressed, the input relay normally closed contact X4 in the PLC program is set to "1", that is, the normally closed contact X4 is closed, the output relay Y1 coil is energized, and its self-locking normally closed contact Y1 is closed to realize the self-locking function; the normally closed contact Y1 of the output relay Y0 is controlled to close and the normally open contact X1 is locked, that is, the stop button SB1 is locked to prevent the stop button SB1 of motor M1 from being pressed by mistake when starting motor M2, thereby shutting down motor M1, which does not meet the control requirements of reverse sequence shutdown.

The coil of the PLC external AC contactor KM2 is energized, the main contact KM2-1 in the main circuit is closed, the power supply of the motor M2 is turned on, and M2 starts running after M1.

2. The reverse sequence shutdown process of two three-phase AC motors

The process of using Mitsubishi FX2N series PLC to control the reverse sequence shutdown of two three-phase AC motors:

Press the stop button SB3 of the motor M2, and set the input relay break contact X3 in the PLC program to "1", that is, the break contact X3 is disconnected, the output relay Y1 coil loses power, and its self-locking make contact Y1 is reset and disconnected, releasing the self-locking function;

At the same time, the interlocking make contact Y1 is reset and disconnected, releasing the lock on the break contact X1, that is, releasing the lock on the stop button SB1, preparing for the operable stop button SB1 to disconnect the contactor KM1, thereby realizing the control requirement of reverse sequence shutdown.

After the Y1 coil loses power, the AC contactor KM2 coil connected to the PLC loses power, the main contact KM2-1 in the main circuit is reset and disconnected, the power supply to the motor M2 is cut off, and M2 stops rotating.

According to the control requirements of reverse sequence shutdown, press the stop button SB1, set the input relay break contact X1 in the PLC program to "1", that is, the break contact X1 is disconnected, the output relay Y0 coil is de-energized, and its self-locking make contact Y0 is reset and disconnected, releasing the self-locking function;

At the same time, the normally closed contact Y0 of the control output relay Y1 is reset and disconnected to prevent Y1 from being energized before Y0 is energized, which does not meet the sequential start control requirements.

After the Y0 coil loses power, the AC contactor KM1 coil connected to the PLC loses power, the main contact KM1-1 in the main circuit resets and disconnects, the power supply of the motor M1 is cut off, and M1 stops after M2.