Consider the following regarding Diesel Generator (DG) sets:1.An AMF (Auto Mains Failure) panel is required to automatically start the DG set when the main power fails.2.The DG set room requires adequate ventilation to ensure combustion and to dissipate heat.3.The Neutral of the DG set should never be earthed to avoid circulating currents.Which of the statements given above is/are correct?

Correct Answer: A - 1 and 2 only

Quick Concept Explanation

Protective earthing provides a low-impedance path for fault current and stabilizes exposed conductive parts/neutral references. Earth resistance should be low enough to meet protection requirements and is checked periodically because soil/moisture/corrosion can change electrode performance. Key relation: Touch voltage and disconnection time depend on earthing and protective-device coordination.

Exam focus: Low earth resistance is desirable—not high resistance. Common trap: Never state that high earth resistance improves safety.

Statement-wise Verification

• Statement 1 - Correct.
  An AMF (Auto Mains Failure) panel is required to automatically start the DG set when the main power fails.
  Low earth resistance is desirable—not high resistance.
• Statement 2 - Correct.
  The DG set room requires adequate ventilation to ensure combustion and to dissipate heat.
  Low earth resistance is desirable—not high resistance.
• Statement 3 - Incorrect.
  The Neutral of the DG set should never be earthed to avoid circulating currents.
  Generator neutral earthing is designed to provide a reference and fault-protection path according to the earthing system; it is not categorically prohibited

Core Concept

Protective earthing provides a low-impedance path for fault current and stabilizes exposed conductive parts/neutral references. Earth resistance should be low enough to meet protection requirements and is checked periodically because soil/moisture/corrosion can change electrode performance.

Formula / Key Relationship

Touch voltage and disconnection time depend on earthing and protective-device coordination.

Why the Other Options Are Wrong

Option B is incorrect because it includes incorrect statement(s) 3 and omits correct statement(s) 1. Option C is incorrect because it includes incorrect statement(s) 3 and omits correct statement(s) 2. Option D is incorrect because it includes incorrect statement(s) 3.

Exam Shortcut / Approach

Low earth resistance is desirable—not high resistance.

Common Mistake

Never state that high earth resistance improves safety.

Quick Revision

AMF Ventilation and Neutral Earthing is linked with Diesel Generator Sets, Standby Power and Electrical Building Services. Low earth resistance is desirable—not high resistance.