Question

Capacitor is always connected in series with starting winding.

Hint:

In a series RC branch, current leads the voltage. Adding a capacitor in series with the auxiliary winding changes its electrical characteristics from inductive ($R\text{--}L$) to capacitive ($R\text{--}C$), which is the key to creating a phase split.

Answer 1

Step 1: The Phase Split Principle:
Single-phase AC induction motors cannot start by themselves because they generate a pulsating magnetic field rather than a rotating one. To create a rotating field, the single-phase current must be split into two currents with a phase difference of approximately $90^\circ$ electrical.

Step 2: Analyzing Series vs. Parallel Capacitor Connections:
The motor features two windings: the main (running) winding and the auxiliary (starting) winding.

• By wiring a capacitor in series with the starting winding, we introduce a capacitive reactance that shifts the current phase angle, causing it to lead the applied voltage.
• The current in the main winding lags behind the voltage due to its high self-inductance.
• This creates the necessary phase angle displacement between the two magnetic fields, creating a rotating magnetic field.

If the capacitor were placed in parallel, it would act as a simple power factor correction device across the mains supply, and would fail to create any phase difference within the motor windings.

Step 3: Conclusion:
The capacitor must always be placed in series with the starting winding to enable starting torque. The statement is True.