Capacitor Start-Capacitor Run Motor

CAPACITOR START-CAPACITOR RUN MOTOR

In this type of motor, two capacitors are used. One capacitor (Cs) is used for starting purpose and the another capacitor (Cr) is used for running purpose. In this motor, high starting torque is achieved. Fig 3.80 shows the schematic of capacitor start capacitor-run motor.

The value of starting capacitor Cs is large and the value of running capacitor Cr is small. The running capacitor is permanently connected in series with auxiliary winding. When the motor speed picks upto 75% of synchronous speed. The centrifugal switch is opened and the stating capacitor Cs is disconnected from the circuit.

Speed torque characteristics

Fig.3.81 shows the speed-torque characteristics of capacitor start capacitor run motor.

This motors have the following advantages

i) High starting torque

ii) High efficiency

iii) High power factor

Characteristics

i) The percentage of rated starting torque is 200% to 300%.

ii) The rated breakdown torque is upto 250%.

iii) The power factor of the motor is in the range of 0.75 to 0.9.

iv) The efficiency is 60 to 70%

v) The power rating is 1/8 to 1 HP.

Applications

i) Compressors,

ii) Pumps,

iii) Conveyors,

iv) Refrigerators.