The motor has completed the turning function
In general, two contactors are required for normal rotation is a three-phase AC asynchronous motor. Due to the three-phase AC asynchronous motor, when the phase sequence of the power supply is turned down, it will be rotated. The phase sequence of the power supply is turned off, which is to allow any two phase wires in between. The azimuth inversion is good, for example, the azimuth inversion between the AB phases can be rotated. To complete this arbitrary two-phase inversion, two contactors are required. This is a three-phase asynchronous motor. The left side is the main circuit. After the two contactors are phase-adjusted to complete the positive rotation, for example, when the KM1 is closed, the three-phase power ABC is connected to the three terminals of the motor in sequence. At this time, the motor It's true. When KM2 is pulled in, the three phases of the power supply are connected to the three terminals of the motor according to the BAC sequence. At this time, the motor has completed the turning function. On the right is the control circuit of the two contactors. It is an interlock circuit and a self-protection circuit, and there is also a fuse. KM1 and KM2 cannot be connected together, otherwise there is a danger of short circuit, so the auxiliary contact of the two contactors is used in series with each other's coil. In this way, one contactor is energized and will prevent the other one
The contactor is charged again. There are two forward switches in the loop, but only one stop button is required. Fan system Single-phase motors complete the forward rotation by switching the orientation between the starting capacitor and the main and auxiliary windings. This will form two types of magnetic fields, SNSN and NSNS. Of course, it can also achieve similar interlocking through two contactors or relays. Circuit-controlled. In fact, the two main contacts of the contactor are used to switch the capacitor in series between the main winding and the secondary winding through the main contacts of the two contactors, so that the direction of the magnetic field can be changed and the positive rotation can be completed.
As for the control circuit, it is the same as the three-phase asynchronous motor, and it is also a self-protection and interlock circuit. As for DC motors, servo motors, or stepper motors, there are usually corresponding controllers to control them. It may be better to give a negative signal on the controller through a similar start-stop switch. Of course, there is a brushed DC motor, which can also complete the forward rotation by switching the square armature of the armature or the current through the contactor.
