ETO Power Generation & Distribution

Question 1

What is the typical operating voltage for main power distribution on large commercial vessels?

Accepted Answer

440V AC

Answer

440V AC is the standard main distribution voltage on large commercial vessels, balancing transmission efficiency with manageable safety risks for shipboard systems.

Question 2

What type of alternator is most commonly used in a ship's power generation system?

Accepted Answer

Salient pole synchronous generator

Answer

Salient pole synchronous generators are used on ships because they provide stable voltage and frequency control through adjustable field excitation, essential for reliable shipboard power.

Question 3

What is the primary purpose of a bus tie breaker in a ship's electrical distribution system?

Accepted Answer

To connect two separate busbars enabling parallel generator operation

Answer

A bus tie breaker connects two busbars so generators can operate in parallel, increasing total power capacity and allowing load sharing between machines.

Question 4

Which protection relay prevents a generator from absorbing power from the busbar when operating in parallel?

Accepted Answer

Reverse power relay

Answer

The reverse power relay detects when a generator is consuming power from the busbar instead of supplying it, preventing motoring of the prime mover which could cause mechanical damage.

Question 5

What is the standard frequency used for electrical power generation on US-flagged commercial vessels?

Accepted Answer

60 Hz

Answer

US-flagged commercial vessels use 60 Hz, consistent with the US shore power standard, while vessels from many European and Asian countries use 50 Hz.

ETO - Electro-Technical Officer Practice Test

ETO - Electro-Technical Officer Practice Test

ETO Power Generation & Distribution