MTC Marine Technician Electrical & Electronics 2 — Questions and Answers
Question 1: What is the purpose of a marine alternator's voltage regulator?
- To convert AC output to DC
- To maintain a constant output voltage regardless of engine RPM (Correct answer)
- To prevent reverse current flow from the battery
- To step up voltage for high-draw accessories
Correct answer: To maintain a constant output voltage regardless of engine RPM
The voltage regulator keeps alternator output at a stable voltage (typically 13.8–14.4V) across varying engine speeds.
Question 2: A marine VHF radio suddenly displays 'LOW VOLTAGE' during operation. The most likely cause is:
- A blown antenna fuse
- Insufficient battery charge or poor wiring connections (Correct answer)
- A defective squelch circuit
- Overheating of the RF amplifier
Correct answer: Insufficient battery charge or poor wiring connections
Low voltage warnings on marine electronics typically indicate battery depletion or high-resistance connections in the supply circuit.
Question 3: Which wire color is standardized for DC negative (ground) in ABYC marine wiring?
- White or black with yellow stripe
- Yellow
- Black or yellow (Correct answer)
- Green
Correct answer: Black or yellow
ABYC standards designate black or yellow as the color for DC negative conductors in marine electrical systems.
Question 4: What does a marine GFCI (Ground Fault Circuit Interrupter) protect against?
- Overloading of AC circuits only
- Reverse polarity at shore power connections
- Electric shock by detecting small current leakage to ground (Correct answer)
- Corrosion of underwater metal fittings
Correct answer: Electric shock by detecting small current leakage to ground
A GFCI monitors the difference in current between hot and neutral conductors, tripping when leakage current (as low as 4–6 mA) flows to ground.
Question 5: On a marine depth sounder, the transducer sends and receives which type of energy?
- Radio frequency waves
- Infrared light pulses
- Ultrasonic sound waves (Correct answer)
- Microwave signals
Correct answer: Ultrasonic sound waves
Depth sounders use ultrasonic (high-frequency sound) pulses that travel through water and reflect off the bottom to calculate depth.
Question 6: Why should marine electrical wire be tinned (tin-coated) rather than bare copper?
- Tinned wire carries higher current capacity
- Tinning prevents corrosion in the marine environment (Correct answer)
- Tinned wire is lighter weight
- Tinning improves flexibility in cold temperatures
Correct answer: Tinning prevents corrosion in the marine environment
Tinning copper strands protects against oxidation and corrosion caused by the salt-air and humidity typical in marine environments.
Question 7: A bilge pump float switch that is stuck in the 'ON' position will:
- Cause the pump to cycle rapidly
- Run the pump continuously, potentially draining the battery (Correct answer)
- Blow the bilge pump fuse immediately
- Activate the high-water alarm only
Correct answer: Run the pump continuously, potentially draining the battery
A stuck-closed float switch energizes the pump relay continuously, running the pump until the battery is discharged.
MTC Marine Technician Electrical & Electronics 2
What is the purpose of a marine alternator's voltage regulator?