Question

Describe the operation of a capacitor-start induction motor.

Answer 1

A capacitor-start induction motor is a type of single-phase induction motor that utilizes a capacitor in its starting circuit to provide an initial phase shift between the main winding and the auxiliary winding. This phase shift helps the motor generate enough starting torque to overcome the inertia of the load and begin its rotation. Once the motor reaches a certain speed, a switch disconnects the capacitor from the circuit, allowing the motor to continue running using only the main winding.

Here's a step-by-step explanation of the operation of a capacitor-start induction motor:

Start Position:

The motor is initially at rest, and the capacitor is connected in parallel with the auxiliary winding.

Power Supply:

When power is applied to the motor, the main winding and the auxiliary winding receive the same voltage. However, due to the capacitance of the capacitor, the current in the auxiliary winding leads the voltage by almost 90 degrees.

Phase Shift:

The current in the auxiliary winding lags behind the voltage in the main winding by approximately 90 degrees. This phase difference creates a rotating magnetic field in the stator, similar to a two-phase motor, even though it's a single-phase system.

Starting Torque:

The rotating magnetic field produced by the phase-shifted current in the auxiliary winding interacts with the rotor's magnetic field, inducing a torque that initiates the motor's rotation. This starting torque is crucial to overcome the initial inertia of the motor and the connected load.

Acceleration:

As the