How to label the wiring number of the unidirectional operation and continuous operation control circuit of three-phase asynchronous motor?

Controlled by 220V or 380V AC power supply, line numbers are marked from left to right and from top to bottom. Start from one end of the power supply (for example, from the left) and mark to the other end of the power supply.

Starting from 1, it is marked with odd numbers, and each passing element is incremented by one line number until there is a voltage drop element (such as contactor coil); Then, from the other end of the power supply (for example, from the right side) to the other end of the power supply.

Parts with voltage drop (such as contactor coil) from 2 to the last are marked with even numbers. It is worth noting that there cannot be duplicate numbers in the whole picture.

Compared with single-phase asynchronous motor, three-phase asynchronous motor has good running performance and can save various materials. According to the different rotor structure, three-phase asynchronous motor can be divided into cage type and wound type. Cage rotor asynchronous motor is widely used because of its simple structure, reliable operation, light weight and low price. Its main disadvantage is the difficulty of speed regulation.

The rotor and stator of wound three-phase asynchronous motor also have three-phase windings, which are connected with external rheostat through slip rings and brushes. Adjusting the resistance of rheostat can improve the starting performance of motor and adjust the speed of motor.

Extended data

When symmetrical three-phase alternating current is applied to the three-phase stator winding, the rotating magnetic field rotates clockwise along the inner circular space of the stator and rotor at the synchronous speed n 1. Because the rotating magnetic field rotates at the speed of n 1, the rotor conductor is stationary at first, so the rotor conductor will cut the stator rotating magnetic field and produce induced electromotive force (the direction of induced electromotive force is determined by the right-hand rule).

Because both ends of the rotor conductor are short-circuited by short-circuit rings, induced current will be generated in the rotor conductor under the action of induced electromotive force, which is basically consistent with the direction of induced electromotive force. The current-carrying conductor of the rotor is acted by electromagnetic force in the stator magnetic field (the direction of the force is determined by the left-handed rule). The electromagnetic force generates electromagnetic torque on the rotor shaft, which drives the rotor to rotate in the direction of rotating magnetic field.

Through the above analysis, it can be concluded that the working principle of the motor is as follows:

When the three-phase stator winding of the motor is energized with three-phase symmetrical alternating current, it will generate a rotating magnetic field and cut the rotor winding, thus generating an induced current in the rotor winding, and the current-carrying rotor conductor will generate electromagnetic force under the action of the stator rotating magnetic field, thus forming an electromagnetic torque on the motor rotating shaft to drive the motor to rotate, and the motor rotating direction is the same as that of the rotating magnetic field.

Baidu Encyclopedia-Three-phase Asynchronous Motor