A permanent split capacitor (PSC) motor is a type of single-phase induction motor. The circuit diagram of a permanent split-phase motor is shown in the figure below. The permanent split-phase induction motor consists of a squirrel cage rotor and the stator has two windings, viz. starting or auxiliary winding and main or running winding. This motor has one capacitor "C" which is connected in series with the starting winding of the motor. This capacitor is permanently connected in the circuit both at starting and running conditions of the motor.
As the capacitor is permanently connected in the circuit and it splits the single-phase supply into two phase supply for making the motor self-starting, that is why, it is known as permanent-split capacitor induction motor. There is only one capacitor used for the operation of the motor, hence, the permanent split capacitor motor is also known as single-value capacitor motor.
The capacitor C and the starting winding are always in the circuit, hence, this type of motor has no centrifugal switch. Therefore, the permanent split capacitor motor operates in the same way as a balanced 2-phase motor. Consequently, it produces a uniform torque and hence less noisy during the operation.
A permanent split-phase induction motor possesses the following advantages −
The limitations of a permanent split capacitor motor are given as follows −
The permanent-split capacitor motor has a low starting torque which is usually less than the full-load torque.
An electrolytic capacitor cannot be used for continuous operation, hence, oil-filled paper capacitor is used which is larger in size and more expensive.
Some of the applications of permanent split capacitor motors are given below −
Used in fans, blowers, heaters, and air-conditioners.
Used to drive refrigerator compressors.
Also used to drive office machineries, etc.