27 Maintenance Practices questions from the Plant & Utility Ops bank, written for Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd.
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A.IS 10593 / IEC 60599 interpretation of gases in transformer oil: hydrogen for partial discharge, ethylene for hot spots, acetylene for arcing, using ratio methods and the Duval triangle
B.bearings cause roughly 40% of motor failures; vibration velocity is judged against ISO 20816 zones and defect frequencies (BPFO, BPFI) are read in the spectrum
C.intervenes when measured indicators such as vibration, thermography, dissolved gases or discharge activity trend toward limits, instead of on fixed calendar intervals
D.Indian code for transformer maintenance covering silica-gel breather colour, oil level and leaks, bushing cleaning, OLTC oil and the schedule of periodic oil and IR tests
Answer + AI explanation with Pro
2. Which term means: "intervenes when measured indicators such as vibration, thermography, dissolved gases or discharge activity trend toward limits, instead of on fixed calendar intervals"?
Junior
A.IS 10028 Part 3
B.Partial discharge measurement
C.SAP Plant Maintenance
D.Condition-based maintenance
Answer + AI explanation with Pro
3. Which statement is correct?
Junior
A.Condition-based maintenance — Indian code for transformer maintenance covering silica-gel breather colour, oil level and leaks, bushing cleaning, OLTC oil and the schedule of periodic oil and IR tests
B.Condition-based maintenance — intervenes when measured indicators such as vibration, thermography, dissolved gases or discharge activity trend toward limits, instead of on fixed calendar intervals
C.Condition-based maintenance — IEC 62271-4 requires recovery with a gas cart rather than venting, checks of moisture, purity and SO2 decomposition products, and density-monitor lockout before work
D.Condition-based maintenance — IS 10593 / IEC 60599 interpretation of gases in transformer oil: hydrogen for partial discharge, ethylene for hot spots, acetylene for arcing, using ratio methods and the Duval triangle
Answer + AI explanation with Pro
4. What is Infrared thermography?
Junior
A.IEC 62271-4 requires recovery with a gas cart rather than venting, checks of moisture, purity and SO2 decomposition products, and density-monitor lockout before work
B.CMMS module where equipment and functional locations carry maintenance plans that generate notifications and work orders, tracked by MTBF and MTTR
C.live-line survey with an IR camera; a joint running more than about 10–15 K hotter than an identical phase under similar load calls for immediate attention
D.bearings cause roughly 40% of motor failures; vibration velocity is judged against ISO 20816 zones and defect frequencies (BPFO, BPFI) are read in the spectrum
Answer + AI explanation with Pro
5. Which term means: "live-line survey with an IR camera; a joint running more than about 10–15 K hotter than an identical phase under similar load calls for immediate attention"?
Junior
A.Motor bearing monitoring
B.Infrared thermography
C.Partial discharge measurement
D.Condition-based maintenance
Answer + AI explanation with Pro
6. Which statement is correct?
Junior
A.Infrared thermography — IS 10593 / IEC 60599 interpretation of gases in transformer oil: hydrogen for partial discharge, ethylene for hot spots, acetylene for arcing, using ratio methods and the Duval triangle
B.Infrared thermography — tested across a 2.5 mm gap; IS 335 needs at least 30 kV as delivered and 70 kV after treatment, while IS 1866 sets 30–50 kV in-service minimums by voltage class
C.Infrared thermography — live-line survey with an IR camera; a joint running more than about 10–15 K hotter than an identical phase under similar load calls for immediate attention
D.Infrared thermography — bearings cause roughly 40% of motor failures; vibration velocity is judged against ISO 20816 zones and defect frequencies (BPFO, BPFI) are read in the spectrum
Answer + AI explanation with Pro
7. What is Dissolved gas analysis?
Mid
A.IS 10593 / IEC 60599 interpretation of gases in transformer oil: hydrogen for partial discharge, ethylene for hot spots, acetylene for arcing, using ratio methods and the Duval triangle
B.tested across a 2.5 mm gap; IS 335 needs at least 30 kV as delivered and 70 kV after treatment, while IS 1866 sets 30–50 kV in-service minimums by voltage class
C.detects localised insulation breakdown that does not bridge the electrodes, quantified in picocoulombs per IEC 60270 offline or by acoustic, TEV and UHF sensors online
D.intervenes when measured indicators such as vibration, thermography, dissolved gases or discharge activity trend toward limits, instead of on fixed calendar intervals
Answer + AI explanation with Pro
8. Which term means: "IS 10593 / IEC 60599 interpretation of gases in transformer oil: hydrogen for partial discharge, ethylene for hot spots, acetylene for arcing, using ratio methods and the Duval triangle"?
Mid
A.SF6 gas handling
B.Partial discharge measurement
C.Dissolved gas analysis
D.Infrared thermography
Answer + AI explanation with Pro
9. Which statement is correct?
Mid
A.Dissolved gas analysis — intervenes when measured indicators such as vibration, thermography, dissolved gases or discharge activity trend toward limits, instead of on fixed calendar intervals
B.Dissolved gas analysis — IS 10593 / IEC 60599 interpretation of gases in transformer oil: hydrogen for partial discharge, ethylene for hot spots, acetylene for arcing, using ratio methods and the Duval triangle
C.Dissolved gas analysis — live-line survey with an IR camera; a joint running more than about 10–15 K hotter than an identical phase under similar load calls for immediate attention
D.Dissolved gas analysis — detects localised insulation breakdown that does not bridge the electrodes, quantified in picocoulombs per IEC 60270 offline or by acoustic, TEV and UHF sensors online
Answer + AI explanation with Pro
10. What is Oil breakdown voltage?
Junior
A.intervenes when measured indicators such as vibration, thermography, dissolved gases or discharge activity trend toward limits, instead of on fixed calendar intervals
B.tested across a 2.5 mm gap; IS 335 needs at least 30 kV as delivered and 70 kV after treatment, while IS 1866 sets 30–50 kV in-service minimums by voltage class
C.live-line survey with an IR camera; a joint running more than about 10–15 K hotter than an identical phase under similar load calls for immediate attention
D.IS 10593 / IEC 60599 interpretation of gases in transformer oil: hydrogen for partial discharge, ethylene for hot spots, acetylene for arcing, using ratio methods and the Duval triangle
Answer + AI explanation with Pro
11. Which term means: "tested across a 2.5 mm gap; IS 335 needs at least 30 kV as delivered and 70 kV after treatment, while IS 1866 sets 30–50 kV in-service minimums by voltage class"?
Junior
A.Dissolved gas analysis
B.SF6 gas handling
C.Partial discharge measurement
D.Oil breakdown voltage
Answer + AI explanation with Pro
12. Which statement is correct?
Junior
A.Oil breakdown voltage — detects localised insulation breakdown that does not bridge the electrodes, quantified in picocoulombs per IEC 60270 offline or by acoustic, TEV and UHF sensors online
B.Oil breakdown voltage — tested across a 2.5 mm gap; IS 335 needs at least 30 kV as delivered and 70 kV after treatment, while IS 1866 sets 30–50 kV in-service minimums by voltage class
C.Oil breakdown voltage — live-line survey with an IR camera; a joint running more than about 10–15 K hotter than an identical phase under similar load calls for immediate attention
D.Oil breakdown voltage — bearings cause roughly 40% of motor failures; vibration velocity is judged against ISO 20816 zones and defect frequencies (BPFO, BPFI) are read in the spectrum
Answer + AI explanation with Pro
13. What is Partial discharge measurement?
Senior
A.IS 10593 / IEC 60599 interpretation of gases in transformer oil: hydrogen for partial discharge, ethylene for hot spots, acetylene for arcing, using ratio methods and the Duval triangle
B.CMMS module where equipment and functional locations carry maintenance plans that generate notifications and work orders, tracked by MTBF and MTTR
C.detects localised insulation breakdown that does not bridge the electrodes, quantified in picocoulombs per IEC 60270 offline or by acoustic, TEV and UHF sensors online
D.tested across a 2.5 mm gap; IS 335 needs at least 30 kV as delivered and 70 kV after treatment, while IS 1866 sets 30–50 kV in-service minimums by voltage class
Answer + AI explanation with Pro
14. Which term means: "detects localised insulation breakdown that does not bridge the electrodes, quantified in picocoulombs per IEC 60270 offline or by acoustic, TEV and UHF sensors online"?
Senior
A.Dissolved gas analysis
B.SF6 gas handling
C.IS 10028 Part 3
D.Partial discharge measurement
Answer + AI explanation with Pro
15. Which statement is correct?
Senior
A.Partial discharge measurement — detects localised insulation breakdown that does not bridge the electrodes, quantified in picocoulombs per IEC 60270 offline or by acoustic, TEV and UHF sensors online
B.Partial discharge measurement — live-line survey with an IR camera; a joint running more than about 10–15 K hotter than an identical phase under similar load calls for immediate attention
C.Partial discharge measurement — IS 10593 / IEC 60599 interpretation of gases in transformer oil: hydrogen for partial discharge, ethylene for hot spots, acetylene for arcing, using ratio methods and the Duval triangle
D.Partial discharge measurement — Indian code for transformer maintenance covering silica-gel breather colour, oil level and leaks, bushing cleaning, OLTC oil and the schedule of periodic oil and IR tests
Answer + AI explanation with Pro
16. What is IS 10028 Part 3?
Junior
A.detects localised insulation breakdown that does not bridge the electrodes, quantified in picocoulombs per IEC 60270 offline or by acoustic, TEV and UHF sensors online
B.live-line survey with an IR camera; a joint running more than about 10–15 K hotter than an identical phase under similar load calls for immediate attention
C.Indian code for transformer maintenance covering silica-gel breather colour, oil level and leaks, bushing cleaning, OLTC oil and the schedule of periodic oil and IR tests
D.IS 10593 / IEC 60599 interpretation of gases in transformer oil: hydrogen for partial discharge, ethylene for hot spots, acetylene for arcing, using ratio methods and the Duval triangle
Answer + AI explanation with Pro
17. Which term means: "Indian code for transformer maintenance covering silica-gel breather colour, oil level and leaks, bushing cleaning, OLTC oil and the schedule of periodic oil and IR tests"?
Junior
A.Infrared thermography
B.Oil breakdown voltage
C.IS 10028 Part 3
D.SAP Plant Maintenance
Answer + AI explanation with Pro
18. Which statement is correct?
Junior
A.IS 10028 Part 3 — IEC 62271-4 requires recovery with a gas cart rather than venting, checks of moisture, purity and SO2 decomposition products, and density-monitor lockout before work
B.IS 10028 Part 3 — Indian code for transformer maintenance covering silica-gel breather colour, oil level and leaks, bushing cleaning, OLTC oil and the schedule of periodic oil and IR tests
C.IS 10028 Part 3 — bearings cause roughly 40% of motor failures; vibration velocity is judged against ISO 20816 zones and defect frequencies (BPFO, BPFI) are read in the spectrum
D.IS 10028 Part 3 — CMMS module where equipment and functional locations carry maintenance plans that generate notifications and work orders, tracked by MTBF and MTTR
Answer + AI explanation with Pro
19. What is Motor bearing monitoring?
Mid
A.bearings cause roughly 40% of motor failures; vibration velocity is judged against ISO 20816 zones and defect frequencies (BPFO, BPFI) are read in the spectrum
B.detects localised insulation breakdown that does not bridge the electrodes, quantified in picocoulombs per IEC 60270 offline or by acoustic, TEV and UHF sensors online
C.Indian code for transformer maintenance covering silica-gel breather colour, oil level and leaks, bushing cleaning, OLTC oil and the schedule of periodic oil and IR tests
D.intervenes when measured indicators such as vibration, thermography, dissolved gases or discharge activity trend toward limits, instead of on fixed calendar intervals
Answer + AI explanation with Pro
20. Which term means: "bearings cause roughly 40% of motor failures; vibration velocity is judged against ISO 20816 zones and defect frequencies (BPFO, BPFI) are read in the spectrum"?
Mid
A.IS 10028 Part 3
B.Motor bearing monitoring
C.SF6 gas handling
D.Partial discharge measurement
Answer + AI explanation with Pro
21. Which statement is correct?
Mid
A.Motor bearing monitoring — tested across a 2.5 mm gap; IS 335 needs at least 30 kV as delivered and 70 kV after treatment, while IS 1866 sets 30–50 kV in-service minimums by voltage class
B.Motor bearing monitoring — detects localised insulation breakdown that does not bridge the electrodes, quantified in picocoulombs per IEC 60270 offline or by acoustic, TEV and UHF sensors online
C.Motor bearing monitoring — IS 10593 / IEC 60599 interpretation of gases in transformer oil: hydrogen for partial discharge, ethylene for hot spots, acetylene for arcing, using ratio methods and the Duval triangle
D.Motor bearing monitoring — bearings cause roughly 40% of motor failures; vibration velocity is judged against ISO 20816 zones and defect frequencies (BPFO, BPFI) are read in the spectrum
Answer + AI explanation with Pro
22. What is SF6 gas handling?
Senior
A.detects localised insulation breakdown that does not bridge the electrodes, quantified in picocoulombs per IEC 60270 offline or by acoustic, TEV and UHF sensors online
B.IEC 62271-4 requires recovery with a gas cart rather than venting, checks of moisture, purity and SO2 decomposition products, and density-monitor lockout before work
C.tested across a 2.5 mm gap; IS 335 needs at least 30 kV as delivered and 70 kV after treatment, while IS 1866 sets 30–50 kV in-service minimums by voltage class
D.live-line survey with an IR camera; a joint running more than about 10–15 K hotter than an identical phase under similar load calls for immediate attention
Answer + AI explanation with Pro
23. Which term means: "IEC 62271-4 requires recovery with a gas cart rather than venting, checks of moisture, purity and SO2 decomposition products, and density-monitor lockout before work"?
Senior
A.Partial discharge measurement
B.Motor bearing monitoring
C.SF6 gas handling
D.Dissolved gas analysis
Answer + AI explanation with Pro
24. Which statement is correct?
Senior
A.SF6 gas handling — intervenes when measured indicators such as vibration, thermography, dissolved gases or discharge activity trend toward limits, instead of on fixed calendar intervals
B.SF6 gas handling — IEC 62271-4 requires recovery with a gas cart rather than venting, checks of moisture, purity and SO2 decomposition products, and density-monitor lockout before work
C.SF6 gas handling — Indian code for transformer maintenance covering silica-gel breather colour, oil level and leaks, bushing cleaning, OLTC oil and the schedule of periodic oil and IR tests
D.SF6 gas handling — bearings cause roughly 40% of motor failures; vibration velocity is judged against ISO 20816 zones and defect frequencies (BPFO, BPFI) are read in the spectrum
Answer + AI explanation with Pro
25. What is SAP Plant Maintenance?
Junior
A.detects localised insulation breakdown that does not bridge the electrodes, quantified in picocoulombs per IEC 60270 offline or by acoustic, TEV and UHF sensors online
B.Indian code for transformer maintenance covering silica-gel breather colour, oil level and leaks, bushing cleaning, OLTC oil and the schedule of periodic oil and IR tests
C.IEC 62271-4 requires recovery with a gas cart rather than venting, checks of moisture, purity and SO2 decomposition products, and density-monitor lockout before work
D.CMMS module where equipment and functional locations carry maintenance plans that generate notifications and work orders, tracked by MTBF and MTTR
Answer + AI explanation with Pro
26. Which term means: "CMMS module where equipment and functional locations carry maintenance plans that generate notifications and work orders, tracked by MTBF and MTTR"?
Junior
A.SF6 gas handling
B.SAP Plant Maintenance
C.Condition-based maintenance
D.Oil breakdown voltage
Answer + AI explanation with Pro
27. Which statement is correct?
Junior
A.SAP Plant Maintenance — CMMS module where equipment and functional locations carry maintenance plans that generate notifications and work orders, tracked by MTBF and MTTR
B.SAP Plant Maintenance — IEC 62271-4 requires recovery with a gas cart rather than venting, checks of moisture, purity and SO2 decomposition products, and density-monitor lockout before work
C.SAP Plant Maintenance — Indian code for transformer maintenance covering silica-gel breather colour, oil level and leaks, bushing cleaning, OLTC oil and the schedule of periodic oil and IR tests
D.SAP Plant Maintenance — live-line survey with an IR camera; a joint running more than about 10–15 K hotter than an identical phase under similar load calls for immediate attention
Answer + AI explanation with Pro
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