Question

The voltage regulation of alternator at lagging power factor will be _______.

• A. positive and more than regulation at unity power factor
• B. less than at unity power factor
• C. remain unchanged
• D. negative and less than regulation at unity power factor

Hint:

At lagging PF, due to inductive nature of load, more reactive drop occurs → higher voltage regulation.

Answer 1

The Correct Option is A

Step 1: Understand voltage regulation.
Voltage regulation = change in terminal voltage when load is removed: \[ \text{VR} = \frac{E - V}{V} \times 100 \] Where: - $E$ = no-load voltage - $V$ = full-load voltage
Step 2: Effect of power factor.
At lagging power factor:
- Armature reaction is demagnetizing
- Causes $E>V$ → higher voltage drop
Step 3: Compare to unity.
At unity PF, armature reaction is purely resistive → less voltage drop
Hence, VR is:
- Positive
- Larger than that at unity PF
Conclusion: $\boxed{\text{Positive and more than at unity PF}}$