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?
Answer & step-by-step solution
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.
डीज़ल जनरेटर (DG) सेट के संबंध में निम्नलिखित पर विचार कीजिए:
1. मुख्य बिजली विफल होने पर DG सेट को स्वचालित रूप से चालू करने के लिए AMF (Auto Mains Failure) पैनल आवश्यक है।
2. दहन सुनिश्चित करने और ऊष्मा निकालने के लिए DG सेट कक्ष में पर्याप्त वेंटिलेशन आवश्यक है।
3. सर्कुलेटिंग धाराओं से बचने के लिए DG सेट का न्यूट्रल कभी अर्थ नहीं करना चाहिए।
ऊपर दिए गए कथनों में से कौन-सा/से सही है/हैं?
उत्तर और चरणबद्ध हल
A — केवल 1 और 2। AMF पैनल मेन्स फेल होने पर DG स्वतः चालू करता है और DG कक्ष में दहन वायु व ऊष्मा निकासी के लिए वेंटिलेशन चाहिए। DG न्यूट्रल को सुरक्षा और फॉल्ट-धारा पथ के लिए उचित रूप से अर्थ किया जाता है।
विस्तृत हल (मूल भाषा में)
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.
ડીઝલ જનરેટર (DG) સેટ અંગે નીચેનું ધ્યાનમાં લો:
1. મુખ્ય વીજળી નિષ્ફળ જાય ત્યારે DG સેટને આપમેળે ચાલુ કરવા AMF (Auto Mains Failure) પેનલ જરૂરી છે.
2. દહન સુનિશ્ચિત કરવા અને ઉષ્મા દૂર કરવા DG સેટ રૂમમાં પૂરતું વેન્ટિલેશન જરૂરી છે.
3. સર્ક્યુલેટિંગ પ્રવાહો ટાળવા DG સેટના ન્યુટ્રલને ક્યારેય અર્થ ન કરવો જોઈએ.
ઉપર આપેલાં વિધાનોમાંથી કયું/કયાં સાચું/સાચાં છે?
જવાબ અને પગલાવાર ઉકેલ
A — ફક્ત 1 અને 2. AMF પેનલ મેઇન્સ નિષ્ફળ જાય ત્યારે DG આપમેળે ચાલુ કરે છે અને DG રૂમમાં દહન હવા અને ઉષ્મા નિકાલ માટે વેન્ટિલેશન જોઈએ. DG ન્યુટ્રલને સલામતી અને ફોલ્ટ-પ્રવાહ માર્ગ માટે યોગ્ય રીતે અર્થ કરવામાં આવે છે.
વિગતવાર ઉકેલ (મૂળ ભાષામાં)
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.
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