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HV exit exam questions and answers — Set 1

Set 1 of the High Voltage Safety Officer & Switchgear Operations (HV) exit exam bank — 30 of 193 questions, with the correct option marked and a one-line explanation for every one. Read it end to end, jump to a single set, or search it — then sit the same bank as a timed paper. The real DG Shipping exit exam is 30 marks with 15 to pass.

These are the bank's original groupings. Practising deals the whole bank out again every time you reshuffle, so a practice “Set 3” is a different 30 questions each time — the set numbers below are the source file's, and are only used here so the key stays navigable. Options are listed in their original order with fixed letters; when you practise, those move too.

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Set 1 — 30 HV exit exam questions with answers

1. What voltage level is defined as High Voltage (HV) under marine SOLAS and STCW regulations?

  • A. AC voltage exceeding 1,000 Volts (1 kV) between conductors, or >600V to earth
  • B. > 24V
  • C. > 100,000V
  • D. > 110V
Answer: A — AC voltage exceeding 1,000 Volts (1 kV) between conductors, or >600V to earth
In marine electrical engineering, voltages exceeding 1,000V AC (e.g. 3.3 kV, 6.6 kV, 11 kV) are classified as High Voltage.

2. What is the primary hazard of working on High Voltage marine equipment compared to Low Voltage?

  • A. Magnetic tool attraction
  • B. Low sound
  • C. Severe electric arc flash explosion, high-energy blast, and arcing across air gaps
  • D. Slightly warm wires
Answer: C — Severe electric arc flash explosion, high-energy blast, and arcing across air gaps
High Voltage can ionize air and jump across gaps, creating explosive arc flashes with temperatures exceeding 10,000°C.

3. What safety document MUST be issued before performing maintenance on High Voltage switchgear?

  • A. Verbal approval
  • B. Deck log entry
  • C. High Voltage Permit to Work (PTW) and Sanction to Test
  • D. Hot Work Permit only
Answer: C — High Voltage Permit to Work (PTW) and Sanction to Test
HV PTWs enforce formal isolation, proving dead, earthing, key interlocking, and authorized signatures.

4. What mandatory step must be taken immediately after opening an HV circuit breaker and isolator?

  • A. Touch with bare hand
  • B. Spray water
  • C. Prove equipment dead using approved calibrated HV voltage detector, then apply safety earths
  • D. Turn on generator
Answer: C — Prove equipment dead using approved calibrated HV voltage detector, then apply safety earths
Testing with a certified HV voltage indicator ('prove dead') is mandatory before touching conductors or earthing.

5. What medium is commonly used inside modern High Voltage marine circuit breakers for arc quenching?

  • A. Water bath
  • B. Compressed oxygen
  • C. Vacuum (VCB) or Sulfur Hexafluoride gas (SF6)
  • D. Mineral oil
Answer: C — Vacuum (VCB) or Sulfur Hexafluoride gas (SF6)
Vacuum Circuit Breakers (VCB) and SF6 gas breakers rapidly extinguish high-energy electrical arcs.

6. What safety equipment must be worn when racking in or out an HV circuit breaker truck?

  • A. Leather apron
  • B. T-shirt and glasses
  • C. Cotton coveralls
  • D. Arc flash protection suit (rated cal/cm2), arc flash visor/hood, HV insulating gloves, and ear protection
Answer: D — Arc flash protection suit (rated cal/cm2), arc flash visor/hood, HV insulating gloves, and ear protection
Racking operations carry high risk of arc flash; full arc flash PPE suite is mandatory.

7. What is the purpose of earthing switches or portable earthing leads on isolated HV equipment?

  • A. Discharge residual capacitive charge and short-circuit conductors to ground for safety
  • B. Charge batteries
  • C. Increase voltage
  • D. Improve power factor
Answer: A — Discharge residual capacitive charge and short-circuit conductors to ground for safety
Earthing guarantees that conductors remain at ground potential even if accidentally re-energized.

8. What key interlock system is used to enforce strict mechanical sequence during HV switching operations?

  • A. Combination lock
  • B. Card swipe
  • C. Master padlock
  • D. Castell Key Interlock System
Answer: D — Castell Key Interlock System
Castell key interlocks physically prevent incorrect switching operations (e.g. earthing a live busbar).

9. What instrument is used to measure insulation resistance of High Voltage cables and machinery?

  • A. Hydrometer
  • B. High Voltage Megohmmeter (Megger - 2.5 kV or 5 kV DC test voltage)
  • C. Oscilloscope
  • D. Low voltage multimeter
Answer: B — High Voltage Megohmmeter (Megger - 2.5 kV or 5 kV DC test voltage)
HV insulation testing requires 2500V or 5000V DC test voltages to detect dielectric insulation weakness.

10. Who is authorized to issue a High Voltage Permit to Work on a ship?

  • A. Any deck rating
  • B. Certified High Voltage Authorised Person (HVAP) / Chief Engineer / Senior Electrical Officer
  • C. Chief Steward
  • D. Port Watchman
Answer: B — Certified High Voltage Authorised Person (HVAP) / Chief Engineer / Senior Electrical Officer
Only formally trained and certified Authorised Persons (HVAP) can issue HV permits and approve switching schedules.

11. Under STCW Code Table A-III/1-HV, what is the mandatory requirement regarding regulatory compliance and STCW code requirements during High Voltage Safety & Switchgear operations?

  • A. Strict compliance with approved safety procedures and flag state regulations
  • B. Verbal recommendation without documentation
  • C. Optional adherence based on vessel size
  • D. Applicable only during drydock operations
Answer: A — Strict compliance with approved safety procedures and flag state regulations
STCW Code Table A-III/1-HV mandates strict compliance with approved safety protocols for High Voltage Safety & Switchgear.

12. What specific safety precaution must be observed when managing regulatory compliance and STCW code requirements for High Voltage Safety & Switchgear on board?

  • A. Disabling automated safety alarms to save time
  • B. Conducting a thorough risk assessment and briefing all involved personnel prior to starting work
  • C. Delegating tasks exclusively to untrained crew members
  • D. Proceeding without informing the officer on watch
Answer: B — Conducting a thorough risk assessment and briefing all involved personnel prior to starting work
Risk assessments and pre-job briefings ensure all team members understand hazards during High Voltage Safety & Switchgear operations.

13. What is creepage distance on High Voltage insulators?

  • A. Distance between bow and stern
  • B. Cable length
  • C. Busbar thickness
  • D. Shortest distance along outer surface of insulating material between two conductive parts
Answer: D — Shortest distance along outer surface of insulating material between two conductive parts
Insulators use corrugated fins to increase creepage surface distance, preventing surface flashover tracking.

14. What condition occurs when electrical stress breaks down insulating properties of air or solid insulation?

  • A. Magnetic hysteresis
  • B. Phase sync
  • C. Dielectric breakdown / Flashover
  • D. Resistance increase
Answer: C — Dielectric breakdown / Flashover
Dielectric breakdown creates conductive plasma paths, resulting in violent short-circuit arc flashes.

15. What is the function of a Potential Transformer (PT) / Voltage Transformer (VT) in HV switchboards?

  • A. Step up to 100 kV
  • B. Cool generators
  • C. Step down High Voltage (e.g. 6.6 kV) to safe Low Voltage (e.g. 110V) for metering and relays
  • D. Convert AC to DC
Answer: C — Step down High Voltage (e.g. 6.6 kV) to safe Low Voltage (e.g. 110V) for metering and relays
VTs provide accurate low-voltage signals for instruments and protective relays without exposing meters to HV.

16. What is the function of a Current Transformer (CT) in HV switchgear?

  • A. Store energy
  • B. Step up to 10,000A
  • C. Measure water temp
  • D. Step down high primary currents (e.g. 1000A) to standard low secondary currents (1A or 5A) for relays
Answer: D — Step down high primary currents (e.g. 1000A) to standard low secondary currents (1A or 5A) for relays
CTs isolate measurement circuits while converting heavy busbar currents into safe relay inputs.

17. What protective relay detects imbalances between incoming and outgoing currents in HV generator windings?

  • A. Differential Protection Relay (87G)
  • B. Under Voltage Relay (27)
  • C. Reverse Power Relay (32)
  • D. Over Frequency Relay (81)
Answer: A — Differential Protection Relay (87G)
Differential relays trip instantaneously if internal winding insulation fails, clearing internal generator faults.

18. What is the function of a Neutral Grounding Resistor (NGR) in marine HV electrical systems?

  • A. Ground antenna
  • B. Limit earth fault current to a safe value (e.g. 10A - 20A), preventing core damage during single phase-to-ground faults
  • C. Increase fault current
  • D. Heat engine room
Answer: B — Limit earth fault current to a safe value (e.g. 10A - 20A), preventing core damage during single phase-to-ground faults
NGRs restrict phase-to-ground fault currents to manageable levels while maintaining system protection tripping.

19. What hazard is associated with opening the secondary circuit of an energized Current Transformer (CT)?

  • A. Fuse blows
  • B. Extremely high induced open-circuit voltage causing lethal electric shock and explosive CT failure
  • C. CT cools down
  • D. Voltage drops to zero
Answer: B — Extremely high induced open-circuit voltage causing lethal electric shock and explosive CT failure
NEVER open-circuit a live CT secondary; high induced voltage spikes (> 1000V) cause fatal shocks.

20. What testing device is used to check insulation integrity of HV rubber gloves before use?

  • A. Manual air inflation pump / glove tester to check for pinhole leaks, plus visual inspection
  • B. Seawater dip
  • C. Pliers stretch
  • D. Flame check
Answer: A — Manual air inflation pump / glove tester to check for pinhole leaks, plus visual inspection
Air testing inflates gloves to reveal microscopic punctures that could pass high voltage currents.

21. What color is standard for High Voltage warning hazard signs on marine switchboards?

  • A. Green sign
  • B. Yellow background with black skull/lightning symbol and 'DANGER - HIGH VOLTAGE' text
  • C. Pink sign
  • D. White sign with blue text
Answer: B — Yellow background with black skull/lightning symbol and 'DANGER - HIGH VOLTAGE' text
High Voltage enclosures require high-visibility danger signs specifying operating voltage (e.g. DANGER 6.6 kV).

22. What protection is provided by a Reverse Power Relay (32) on a marine HV generator?

  • A. Protects high temp
  • B. Protects low oil
  • C. Trips generator breaker if electrical power flows BACK into generator (motoring the prime mover)
  • D. Protects low frequency
Answer: C — Trips generator breaker if electrical power flows BACK into generator (motoring the prime mover)
Reverse power relays prevent a failed engine from being driven as an electric motor by parallel generators.

23. Which international regulation specifies the minimum standard for regulatory compliance and STCW code requirements concerning High Voltage Safety & Switchgear?

  • A. Port State Control advisory note only
  • B. Tonnage Measurement Convention 1969
  • C. International Load Line Certificate Annex 3
  • D. STCW Code Section A-III/1-HV and relevant SOLAS/MARPOL conventions
Answer: D — STCW Code Section A-III/1-HV and relevant SOLAS/MARPOL conventions
STCW Code Section A-III/1-HV sets international standards for training and operational competency in High Voltage Safety & Switchgear.

24. In the event of an emergency involving regulatory compliance and STCW code requirements during High Voltage Safety & Switchgear tasks, what immediate action is required?

  • A. Attempt to resolve the incident silently without raising the alarm
  • B. Evacuate the vessel immediately without informing the bridge
  • C. Raise the alarm, notify the Officer of the Watch, and execute assigned muster list duties
  • D. Wait until the end of the watch to log the issue
Answer: C — Raise the alarm, notify the Officer of the Watch, and execute assigned muster list duties
Prompt alarm activation ensures emergency response teams can mobilize immediately.

25. What is the purpose of an Arc Flash Detection system inside HV switchboard cubicles?

  • A. Turn on cabin lights
  • B. Detect smoke
  • C. Take photos
  • D. Detect light flash via fiber-optic sensors and trip main breaker in milliseconds before pressure explosion develops
Answer: D — Detect light flash via fiber-optic sensors and trip main breaker in milliseconds before pressure explosion develops
Optical arc sensors combined with overcurrent relays trip switchgear in under 2–5 milliseconds to minimize arc flash damage.

26. What is partial discharge (PD) in High Voltage electrical apparatus?

  • A. Battery charge
  • B. Load shedding
  • C. Microscopic electrical sparks inside insulation voids that gradually erode dielectric strength
  • D. Complete breaker trip
Answer: C — Microscopic electrical sparks inside insulation voids that gradually erode dielectric strength
Partial discharge monitoring detects insulation degradation early, preventing catastrophic breakdown.

27. What insulation class is standard for marine HV electric motor windings (Class F or Class H)?

  • A. Wood insulation
  • B. Paper insulation
  • C. Cotton thread
  • D. Class F (155°C max temp) or Class H (180°C max temp) with vacuum pressure impregnation (VPI)
Answer: D — Class F (155°C max temp) or Class H (180°C max temp) with vacuum pressure impregnation (VPI)
Class F/H resin impregnation provides high dielectric strength and thermal resistance for marine motor windings.

28. What device is used to safely discharge stored electrical energy in large HV capacitor banks before maintenance?

  • A. Water spray
  • B. Screwdriver touch
  • C. Fan
  • D. Built-in discharge resistors and portable earthing/shorting probe
Answer: D — Built-in discharge resistors and portable earthing/shorting probe
Capacitors retain lethal charges long after power is disconnected; earthing probes ensure complete discharge.

29. What safety distance (air clearance) must be maintained from exposed un-insulated 6.6 kV conductors?

  • A. 1 mm
  • B. Minimum safe clearance distance (~150 mm to 250 mm depending on standard, plus safety margin)
  • C. Zero
  • D. 10 meters
Answer: B — Minimum safe clearance distance (~150 mm to 250 mm depending on standard, plus safety margin)
High Voltage requires minimum physical air clearance gaps to prevent flashover ionization.

30. What test is performed to measure moisture and gas breakdown in SF6 circuit breaker gas?

  • A. Titration
  • B. SF6 gas purity, dew point, and decomposition product analysis
  • C. Salt water test
  • D. Smoke test
Answer: B — SF6 gas purity, dew point, and decomposition product analysis
SF6 gas purity and moisture content must be verified to ensure high dielectric breakdown strength.

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