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SarkariResultOutAdditional Assistant Engineer (Electrical) · 2026

Previous Year Question

Why are three-phase induction machines generally unsuitable for applications requiring rapid acceleration and deceleration due to dynamic performance limitations?
  1. They operate with high slip at all speeds.
  2. Their inherent inertia limits fast speed changes.
  3. They cannot handle variable load conditions.
  4. They produce excessive electromagnetic noise.

Correct answer: B

Explanation

Rapid speed change requires large accelerating/decelerating torque relative to the combined mechanical inertia. The rotor and connected mechanical system therefore limit how quickly speed can change, making option B the best answer among the choices.

Step-by-step solution

Rotor Inertia explanatory diagram

Correct Answer

B — Their inherent inertia limits fast speed changes.

Explanation

Rapid speed change requires large accelerating/decelerating torque relative to the combined mechanical inertia. The rotor and connected mechanical system therefore limit how quickly speed can change, making option B the best answer among the choices.

Key Concept

Rotor Inertia

Exam Point

Dynamic speed response is fundamentally limited by torque-to-inertia ratio.

Exam tip

Dynamic speed response is fundamentally limited by torque-to-inertia ratio.

Quick method

Dynamic speed response is fundamentally limited by torque-to-inertia ratio.