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NETA 3 (Level III) – Exam 2 EXAM QUESTIONS AND
CORRECT DETAILED ANSWERS LATEST UPDATE THIS
YEAR
Exam Coverage – NETA 3 (Level III) – Exam 2
This exam is for Senior Level certification by the InterNational Electrical Testing Association
(NETA). It covers advanced principles of acceptance and maintenance testing of electrical power
equipment and systems. Key topics include: protective relay testing and
calibration (overcurrent, differential, distance, directional, synchronism, and transfer trip
schemes); high-voltage circuit breaker testing (SF₆, vacuum, air magnetic, oil – timing, travel,
contact resistance, insulation resistance, power factor/ dissipation factor, and gas
analysis); transformer testing (turns ratio (TTR), winding resistance, excitation current,
insulation power factor, sweep frequency response analysis (SFRA), dissolved gas analysis
(DGA), and bushing testing); motor and generator testing (insulation resistance (megger),
polarization index (PI), step-voltage (DC hipot), surge comparison, partial discharge, and
vibration analysis); cable testing and diagnostics (VLF, tan delta, DC hipot, partial discharge, and
fault locating); switchgear and switchboard testing (ground-fault coordination, breaker trip
units, bus bar tests); grounding systems (fall-of-potential, clamp-on testing, soil
resistivity); protective device coordination (time-current characteristic curves (TCC), selectivity
studies, and arc flash analysis); power quality (harmonic analysis, PQ monitoring, transient
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capture); commissioning and field testing (test plans, safety grounding (LOTO), administrative
controls); standards (ANSI/NETA MTS, ATS, IEEE, ASTM); and data analysis, reporting, and
troubleshooting.
200 Randomized, Scenario-Based MCQs for NETA 3 (Level III) Exam 2
1. A senior test technician is performing a Doble power factor test on a 15 kV vacuum circuit
breaker pole assembly. Which condition would most likely indicate moisture contamination
inside the vacuum interrupter?
A) A sharp increase in power factor at the same test voltage
B) A high insulation resistance reading with steady power factor
C) A negative power factor reading due to inductive kickback
D) A power factor value below 0.1% at rated voltage
Answer: A
RATIONALE: An abrupt increase in power factor as voltage rises (unstable tip-up) often indicates
internal moisture, tracking, or contamination within the vacuum interrupter’s external
insulation.
2. During acceptance testing of a new 25 MVA power transformer, the sweep frequency
response analysis (SFRA) shows a significant deviation between phases in the high-frequency
region (>1 MHz). What is the most likely cause?
A) Normal manufacturing variation within acceptable limits
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B) A possible winding deformation or shifting that occurred during shipping
C) Incorrect tap changer position on one phase only
D) Moisture in the oil affecting capacitance
Answer: B
RATIONALE: SFRA deviations at higher frequencies typically indicate mechanical movement or
deformation of transformer windings. Phase-to-phase comparison helps diagnose
shipping/packing damage.
3. Which rule requires that test instruments must be calibrated against certified standards
traceable to NIST and that the calibration interval must be defined based on the manufacturer’s
recommendations?
A) NETA ATS 2007
B) ANSI/NETA MTS Table 100.8
C) ASTM D924
D) IEEE 400.2
Answer: B
RATIONALE: ANSI/NETA MTS includes requirements for calibration traceability and intervals;
Section 100.8 (or similar) specifies that test equipment must be calibrated at defined intervals
by a laboratory with traceability to NIST.
4. A 13.8 kV SF₆ circuit breaker fails a timing test: the “close” operation is 8 milliseconds slower
than the previous test record. The manufacturer’s limit is ±5 milliseconds. What is the most
likely cause?
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A) Decreased SF₆ gas pressure in the operating mechanism
B) Normal aging of the breaker; no action required
C) Misadjusted or worn operating mechanism linkage or dashpot
D) Main contact erosion causing longer contact travel
Answer: C
RATIONALE: A change in close timing beyond tolerance often indicates mechanical issues
(linkage wear, lubrication, or dashpot settings). SF₆ pressure affects dielectric, not close time
(unless hydraulic/pneumatic).
5. When performing a circuit-breaker contact resistance test (micro-ohmmeter method), the
test current should be at least what value to burn through surface oxides?
A) 1 A DC
B) 10 A DC
C) 100 A DC
D) 50 A AC
Answer: C
RATIONALE: NETA standards recommend a minimum of 100 A DC for contact resistance testing
to penetrate film oxides and provide repeatable micro-ohm readings.
6. A technician analyzes dissolved gas analysis (DGA) results on a 69 kV transformer and finds
elevated acetylene (C₂H₂) along with hydrogen and methane. This gas combination is most
indicative of:
A) Cellulose insulation overheating (thermal fault)
NETA 3 (Level III) – Exam 2 EXAM QUESTIONS AND
CORRECT DETAILED ANSWERS LATEST UPDATE THIS
YEAR
Exam Coverage – NETA 3 (Level III) – Exam 2
This exam is for Senior Level certification by the InterNational Electrical Testing Association
(NETA). It covers advanced principles of acceptance and maintenance testing of electrical power
equipment and systems. Key topics include: protective relay testing and
calibration (overcurrent, differential, distance, directional, synchronism, and transfer trip
schemes); high-voltage circuit breaker testing (SF₆, vacuum, air magnetic, oil – timing, travel,
contact resistance, insulation resistance, power factor/ dissipation factor, and gas
analysis); transformer testing (turns ratio (TTR), winding resistance, excitation current,
insulation power factor, sweep frequency response analysis (SFRA), dissolved gas analysis
(DGA), and bushing testing); motor and generator testing (insulation resistance (megger),
polarization index (PI), step-voltage (DC hipot), surge comparison, partial discharge, and
vibration analysis); cable testing and diagnostics (VLF, tan delta, DC hipot, partial discharge, and
fault locating); switchgear and switchboard testing (ground-fault coordination, breaker trip
units, bus bar tests); grounding systems (fall-of-potential, clamp-on testing, soil
resistivity); protective device coordination (time-current characteristic curves (TCC), selectivity
studies, and arc flash analysis); power quality (harmonic analysis, PQ monitoring, transient
, Page 2 of 91
capture); commissioning and field testing (test plans, safety grounding (LOTO), administrative
controls); standards (ANSI/NETA MTS, ATS, IEEE, ASTM); and data analysis, reporting, and
troubleshooting.
200 Randomized, Scenario-Based MCQs for NETA 3 (Level III) Exam 2
1. A senior test technician is performing a Doble power factor test on a 15 kV vacuum circuit
breaker pole assembly. Which condition would most likely indicate moisture contamination
inside the vacuum interrupter?
A) A sharp increase in power factor at the same test voltage
B) A high insulation resistance reading with steady power factor
C) A negative power factor reading due to inductive kickback
D) A power factor value below 0.1% at rated voltage
Answer: A
RATIONALE: An abrupt increase in power factor as voltage rises (unstable tip-up) often indicates
internal moisture, tracking, or contamination within the vacuum interrupter’s external
insulation.
2. During acceptance testing of a new 25 MVA power transformer, the sweep frequency
response analysis (SFRA) shows a significant deviation between phases in the high-frequency
region (>1 MHz). What is the most likely cause?
A) Normal manufacturing variation within acceptable limits
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B) A possible winding deformation or shifting that occurred during shipping
C) Incorrect tap changer position on one phase only
D) Moisture in the oil affecting capacitance
Answer: B
RATIONALE: SFRA deviations at higher frequencies typically indicate mechanical movement or
deformation of transformer windings. Phase-to-phase comparison helps diagnose
shipping/packing damage.
3. Which rule requires that test instruments must be calibrated against certified standards
traceable to NIST and that the calibration interval must be defined based on the manufacturer’s
recommendations?
A) NETA ATS 2007
B) ANSI/NETA MTS Table 100.8
C) ASTM D924
D) IEEE 400.2
Answer: B
RATIONALE: ANSI/NETA MTS includes requirements for calibration traceability and intervals;
Section 100.8 (or similar) specifies that test equipment must be calibrated at defined intervals
by a laboratory with traceability to NIST.
4. A 13.8 kV SF₆ circuit breaker fails a timing test: the “close” operation is 8 milliseconds slower
than the previous test record. The manufacturer’s limit is ±5 milliseconds. What is the most
likely cause?
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A) Decreased SF₆ gas pressure in the operating mechanism
B) Normal aging of the breaker; no action required
C) Misadjusted or worn operating mechanism linkage or dashpot
D) Main contact erosion causing longer contact travel
Answer: C
RATIONALE: A change in close timing beyond tolerance often indicates mechanical issues
(linkage wear, lubrication, or dashpot settings). SF₆ pressure affects dielectric, not close time
(unless hydraulic/pneumatic).
5. When performing a circuit-breaker contact resistance test (micro-ohmmeter method), the
test current should be at least what value to burn through surface oxides?
A) 1 A DC
B) 10 A DC
C) 100 A DC
D) 50 A AC
Answer: C
RATIONALE: NETA standards recommend a minimum of 100 A DC for contact resistance testing
to penetrate film oxides and provide repeatable micro-ohm readings.
6. A technician analyzes dissolved gas analysis (DGA) results on a 69 kV transformer and finds
elevated acetylene (C₂H₂) along with hydrogen and methane. This gas combination is most
indicative of:
A) Cellulose insulation overheating (thermal fault)
