How to write the principle of forward and reverse rotation of three phase motor

Two contactors are used for positive and negative control, and the main circuit outlet only needs to be adjusted to the two sides. The control line is a positive auxiliary normally closed control positive coil, and an anti-auxiliary normally closed control positive coil.

Commutation with two contactors for positive and negative conversion!

In order to realize forward and reverse rotation adjustment of the motor, any two of the phase sequence of its power supply can be adjusted (called commutation).

In order to ensure that the phase sequence of the motor can be reliably changed when the two contactors are moving, the upper wiring of the contactor should be consistent, and the lower port of the contactor should be phase-adjusted.

Due to the reversal of the two-phase phase sequence, it is necessary to ensure that the two km coils cannot be energized at the same time, otherwise a serious phase-to-phase short-circuit fault will occur, so interlocking must be adopted. For the sake of safety, the double interlocking forward and reverse control line of button interlocking (mechanical) and contactor interlocking (as shown in the figure below) is often used

With the use of button interlock, even if the forward and reverse buttons are pressed at the same time, the two contactors used for phase adjustment cannot be energized at the same time, and the phase-to-phase short circuit is mechanically avoided.

In addition, due to the interlocking of the contactor of the application, as long as one of the contactors is energized, its long closed contact will not be closed, so that in the application of mechanical and electrical double interlocking, the power supply system of the motor can not be short-circuited between phases, which effectively protects the motor, and also avoids the accident caused by the interphase short circuit and burns out the contactor when the phase is adjusted.

The voltage between the L1 and L3 phases of the three-phase power supply is completely short-circuited by reversing the main contact of the electromagnetic contactor, so there will be a large short-circuit current flowing through and burning out the circuit.

Therefore, in order to prevent the short-circuit accident of the two-phase power supply, the main contacts of the contactor KM1 and KM2 are never allowed to close at the same time.

As shown in the figure above, the electrical schematic diagram of the forward and reverse control of the interlocking contactor of the three-phase asynchronous motor, in order to ensure that when one contactor is energized, the other contactor cannot be energized, so as to avoid the interphase short circuit of the power supply, the normally closed auxiliary contact of the reverse contactor KM2 is connected in series in the forward rotation control circuit, and the normally closed auxiliary contact of the forward rotation contactor KM1 is connected in series in the reverse control circuit.

When the contactor KM1 is energized, the normally closed contact of KM1 stringed in the reversal control circuit is broken, the reversal control circuit is cut off, and the main contact of KM2 cannot be closed when the main contact of KM1 is closed. Similarly, when the contactor KM2 is energized, the normally closed contact of KM2 is broken, cutting off the forward rotation control circuit, and reliably avoiding the occurrence of the two-phase power supply short circuit accident.

The forward and reverse rotation of the motor is simple and effective, and it will be visible at a glance.

Good evening 1, the three-phase asynchronous motor can achieve forward and reverse rotation as long as the phase sequence of the three-phase electricity is changed, and the two AC contactors are configured to be wired in different phase sequences, and the forward and reverse rotation of the motor is controlled by controlling and switching the suction of the two AC contactors. 2. The two phase wires can be reversed, and the three-phase asynchronous motor can also be reversed. 3. Careful return often requires forward and reverse operation, and forward and reverse switches can be installed.

4. Reverse contactors and frequency converters can be installed to realize the forward and reverse rotation of three-phase asynchronous motors. 5. The phase sequence can be changed by exchanging any cuckoo phase line, so as to realize the reversal of the three-phase asynchronous motor. 6. You can go to the electromechanical company and buy a three-phase reverse switch to replace the original load switch, and you can realize forward and reverse reversal.

<>1. Single-phase motor generally refers to a low-power single-phase asynchronous motor powered by a single-phase AC power supply. The single-phase motor has two coils, three heads, one end of the two coils is connected together as a head (common end), one head of the starting coil, one head of the running coil, the starting capacitor is connected between the running coil and the starting coil, the motor rotates when the power supply is connected to the common end and the running coil, and the motor reverses when the power supply is connected to the common end and the starting coil. By changing the connection method of the capacitor with a switch or relay, the forward and reverse rotation of the single-phase motor can be realized.

2. For the forward and reverse rotation of the three-phase motor, only need to change the wiring position of any two of the three power cords of the three-phase motor.