Power Generation & Distribution Flashcards
7 cards from real ETO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Power Generation & Distribution flashcards as text
According to classification society rules, what is the maximum allowable voltage drop for main lighting circuits on ships?
Answer: 2.5%
Classification societies typically limit voltage drop in lighting circuits to 2.5% to ensure adequate and consistent illumination levels throughout the vessel and preserve lamp life.
Which source provides emergency electrical power to essential services if all main generators fail on a ship?
Answer: Emergency generator
An emergency generator, required by SOLAS, automatically starts and connects to the emergency switchboard to supply essential services whenever main power is lost.
According to SOLAS requirements, what is the minimum duration for which an emergency generator on a cargo ship must be capable of supplying power?
Answer: 18 hours
SOLAS Chapter II-1 requires the emergency source of electrical power on cargo ships to supply essential services for a minimum of 18 hours without refueling.
What is the primary purpose of performing an insulation resistance test on a ship's electrical equipment?
Answer: To detect deterioration of electrical insulation that may lead to earth faults or electric shock hazards
Insulation resistance testing detects moisture ingress, physical damage, or aging insulation before they cause earth faults, equipment damage, or dangerous electric shock hazards.
Why do ships typically use an IT (Insulated Neutral) earthing system rather than a solidly earthed neutral system?
Answer: To allow continued operation during a single earth fault while crew locates and repairs it
The IT system allows the ship to continue operating safely with a single earth fault present, giving crew time to identify and correct the fault without immediate power interruption to essential services.
What alarm condition is activated on a ship's main switchboard when insulation resistance drops below the minimum acceptable threshold?
Answer: Earth fault alarm
An earth fault alarm is triggered when the insulation monitoring device detects that system insulation resistance has fallen below the set threshold, indicating current leakage to the hull.
What is the minimum insulation resistance value typically required for low-voltage electrical equipment on ships according to classification society standards?
Answer: 1 MΩ
Classification societies require a minimum of 1 MΩ insulation resistance for low-voltage equipment; healthy new installations typically measure considerably higher, with values below 1 MΩ indicating a fault condition.