Consider the following statements regarding Preventive Maintenance of industrial electrical systems:
1. Thermography is used to detect "hot spots" in electrical connections and panels.
2. Measurement of Earth Resistance should be done periodically using an Earth Tester.
3. Dielectric strength testing is performed only on cables and never on transformer oil.
Which of the statements given above is/are correct?
Answer & step-by-step solution
Preventive maintenance aims to detect deterioration before failure. Electrical programs combine thermal inspection, insulation testing, earth-continuity/resistance checks, contact tightening, protection testing and oil diagnostics where applicable. Key relation: Thermal principle: abnormal I²R heating reveals high-resistance connections. Dielectric-strength tests determine the electric stress at which insulation breaks down under the specified test method.
Exam focus: Thermography = hot spots; earth tester = grounding health; BDV test = transformer oil insulation quality. Common trap: Believing dielectric testing applies only to solid cable insulation.
Statement-wise Verification
- Statement 1 - Correct.
Thermography is used to detect "hot spots" in electrical connections and panels.
Thermography identifies temperature rise caused by loose joints, overload, imbalance, poor contacts and other high-resistance defects without shutting equipment down in many cases. - Statement 2 - Correct.
Measurement of Earth Resistance should be done periodically using an Earth Tester.
Earth-electrode/earthing-system resistance is checked periodically with suitable earth-resistance test methods/instruments as part of electrical safety maintenance. - Statement 3 - Incorrect.
Dielectric strength testing is performed only on cables and never on transformer oil.
Breakdown-voltage/dielectric-strength testing is a standard condition test for transformer insulating oil as well as for other insulation systems.
Core Concept
Preventive maintenance aims to detect deterioration before failure. Electrical programs combine thermal inspection, insulation testing, earth-continuity/resistance checks, contact tightening, protection testing and oil diagnostics where applicable.
Formula / Key Relationship
Thermal principle: abnormal I²R heating reveals high-resistance connections. Dielectric-strength tests determine the electric stress at which insulation breaks down under the specified test method.
Step-by-Step Check
Established maintenance practices confirm 1 and 2. Transformer-oil dielectric testing provides a direct counterexample to statement 3. Option A.
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.
Answer-Key Verification Note
The uploaded provisional key marks C . After independent technical verification, the defensible answer is A . This discrepancy is stated explicitly rather than silently copying the provisional key.
Exam Shortcut / Approach
Thermography = hot spots; earth tester = grounding health; BDV test = transformer oil insulation quality.
Common Mistake
Believing dielectric testing applies only to solid cable insulation.
Quick Revision
Thermography Earthing and Dielectric Tests is linked with Preventive Maintenance, Maintenance and Industrial Electrical Systems. Thermography = hot spots; earth tester = grounding health; BDV test = transformer oil insulation quality.
औद्योगिक विद्युत प्रणालियों के निवारक रखरखाव (Preventive Maintenance) के संबंध में निम्नलिखित कथनों पर विचार कीजिए:
1. विद्युत कनेक्शनों और पैनलों में "हॉट स्पॉट" का पता लगाने के लिए थर्मोग्राफी का उपयोग होता है।
2. अर्थ प्रतिरोध का मापन अर्थ टेस्टर से समय-समय पर किया जाना चाहिए।
3. डाइइलेक्ट्रिक स्ट्रेंथ परीक्षण केवल केबलों पर किया जाता है, ट्रांसफार्मर तेल पर कभी नहीं।
ऊपर दिए गए कथनों में से कौन-सा/से सही है/हैं?
उत्तर और चरणबद्ध हल
A — केवल 1 और 2। थर्मोग्राफी असामान्य I²R तापन से हॉट स्पॉट पकड़ती है और अर्थ टेस्टर अर्थिंग की स्थिति जाँचता है। ट्रांसफार्मर तेल का भी BDV (डाइइलेक्ट्रिक स्ट्रेंथ) परीक्षण होता है, इसलिए कथन 3 गलत है।
विस्तृत हल (मूल भाषा में)
Statement-wise Verification
- Statement 1 - Correct.
Thermography is used to detect "hot spots" in electrical connections and panels.
Thermography identifies temperature rise caused by loose joints, overload, imbalance, poor contacts and other high-resistance defects without shutting equipment down in many cases. - Statement 2 - Correct.
Measurement of Earth Resistance should be done periodically using an Earth Tester.
Earth-electrode/earthing-system resistance is checked periodically with suitable earth-resistance test methods/instruments as part of electrical safety maintenance. - Statement 3 - Incorrect.
Dielectric strength testing is performed only on cables and never on transformer oil.
Breakdown-voltage/dielectric-strength testing is a standard condition test for transformer insulating oil as well as for other insulation systems.
Core Concept
Preventive maintenance aims to detect deterioration before failure. Electrical programs combine thermal inspection, insulation testing, earth-continuity/resistance checks, contact tightening, protection testing and oil diagnostics where applicable.
Formula / Key Relationship
Thermal principle: abnormal I²R heating reveals high-resistance connections. Dielectric-strength tests determine the electric stress at which insulation breaks down under the specified test method.
Step-by-Step Check
Established maintenance practices confirm 1 and 2. Transformer-oil dielectric testing provides a direct counterexample to statement 3. Option A.
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.
Answer-Key Verification Note
The uploaded provisional key marks C . After independent technical verification, the defensible answer is A . This discrepancy is stated explicitly rather than silently copying the provisional key.
Exam Shortcut / Approach
Thermography = hot spots; earth tester = grounding health; BDV test = transformer oil insulation quality.
Common Mistake
Believing dielectric testing applies only to solid cable insulation.
Quick Revision
Thermography Earthing and Dielectric Tests is linked with Preventive Maintenance, Maintenance and Industrial Electrical Systems. Thermography = hot spots; earth tester = grounding health; BDV test = transformer oil insulation quality.
ઔદ્યોગિક વિદ્યુત પ્રણાલીઓની નિવારક જાળવણી (Preventive Maintenance) અંગે નીચેનાં વિધાનો ધ્યાનમાં લો:
1. વિદ્યુત જોડાણો અને પેનલોમાં "હોટ સ્પોટ" શોધવા થર્મોગ્રાફીનો ઉપયોગ થાય છે.
2. અર્થ અવરોધનું માપન અર્થ ટેસ્ટરથી સમયાંતરે થવું જોઈએ.
3. ડાઇઇલેક્ટ્રિક સ્ટ્રેન્થ પરીક્ષણ ફક્ત કેબલ પર જ થાય છે, ટ્રાન્સફોર્મર તેલ પર ક્યારેય નહીં.
ઉપર આપેલાં વિધાનોમાંથી કયું/કયાં સાચું/સાચાં છે?
જવાબ અને પગલાવાર ઉકેલ
A — ફક્ત 1 અને 2. થર્મોગ્રાફી અસામાન્ય I²R ગરમીથી હોટ સ્પોટ પકડે છે અને અર્થ ટેસ્ટર અર્થિંગની સ્થિતિ ચકાસે છે. ટ્રાન્સફોર્મર તેલનું પણ BDV (ડાઇઇલેક્ટ્રિક સ્ટ્રેન્થ) પરીક્ષણ થાય છે, તેથી વિધાન 3 ખોટું છે.
વિગતવાર ઉકેલ (મૂળ ભાષામાં)
Statement-wise Verification
- Statement 1 - Correct.
Thermography is used to detect "hot spots" in electrical connections and panels.
Thermography identifies temperature rise caused by loose joints, overload, imbalance, poor contacts and other high-resistance defects without shutting equipment down in many cases. - Statement 2 - Correct.
Measurement of Earth Resistance should be done periodically using an Earth Tester.
Earth-electrode/earthing-system resistance is checked periodically with suitable earth-resistance test methods/instruments as part of electrical safety maintenance. - Statement 3 - Incorrect.
Dielectric strength testing is performed only on cables and never on transformer oil.
Breakdown-voltage/dielectric-strength testing is a standard condition test for transformer insulating oil as well as for other insulation systems.
Core Concept
Preventive maintenance aims to detect deterioration before failure. Electrical programs combine thermal inspection, insulation testing, earth-continuity/resistance checks, contact tightening, protection testing and oil diagnostics where applicable.
Formula / Key Relationship
Thermal principle: abnormal I²R heating reveals high-resistance connections. Dielectric-strength tests determine the electric stress at which insulation breaks down under the specified test method.
Step-by-Step Check
Established maintenance practices confirm 1 and 2. Transformer-oil dielectric testing provides a direct counterexample to statement 3. Option A.
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.
Answer-Key Verification Note
The uploaded provisional key marks C . After independent technical verification, the defensible answer is A . This discrepancy is stated explicitly rather than silently copying the provisional key.
Exam Shortcut / Approach
Thermography = hot spots; earth tester = grounding health; BDV test = transformer oil insulation quality.
Common Mistake
Believing dielectric testing applies only to solid cable insulation.
Quick Revision
Thermography Earthing and Dielectric Tests is linked with Preventive Maintenance, Maintenance and Industrial Electrical Systems. Thermography = hot spots; earth tester = grounding health; BDV test = transformer oil insulation quality.
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