The Starting Method Of Single-phase Motor

The starting methods of a 220V AC single-phase motor can be roughly divided into the following types:
The first type is the phase separated starting type, which is assisted by the auxiliary starting winding for starting. Its starting torque is not large. The operating speed remains roughly constant. Mainly used in electric fans, air conditioning fan motors, washing machines and other motors.
The second type is that the centrifugal switch is turned on when the motor is stationary, and the starting capacitor participates in the starting work after being powered on. When the rotor speed reaches 70% to 80% of the rated value, the centrifugal switch will automatically trip, and the starting capacitor will complete the task and be disconnected. The starting winding does not participate in the operation work, while the motor continues to operate with the running winding coil.
The third type is that the centrifugal switch is turned on when the motor is stationary, and the starting capacitor participates in the starting work after being powered on. When the rotor speed reaches 70% to 80% of the rated value, the centrifugal switch will automatically trip, and the starting capacitor will complete the task and be disconnected. And the running capacitor is connected in series to the starting winding to participate in the operation work. This connection method is generally used in places with large and unstable loads such as air compressors, cutting machines, woodworking machines, etc.
If a motor with a centrifugal switch cannot be successfully started in a short period of time, the winding coils will quickly burn out.
Capacitance value: Dual value capacitor motors have a large starting capacitance and a small operating capacitance, with a withstand voltage generally greater than 400 V.
2. Forward and reverse control:
Figure D is a wiring diagram with forward and reverse switches. Usually, the resistance values of the starting winding and running winding of this type of motor are the same, which means that the wire diameter and number of coils of the starting winding and running winding of the motor are exactly the same. This type of motor is commonly used in washing machines. This forward and reverse control method is simple and does not require complex conversion switches.
The judgment of starting and running windings usually shows that the starting winding has a much higher DC resistance than the running winding, which can be measured with a multimeter. The DC resistance of a typical operating winding is a few ohms, while the DC resistance of a starting winding ranges from tens of ohms to several tens of ohms.