Marine Electrotechnology. Test 1

A 10% reduction in generator speed occurs due to a faulty governor. The likely consequence for each motor powered from this generator is to:

Increase motor power by about 10%
Reduce motor speed by about 10%
Reduce motor volt drop by about 10%
Increase motor speed by about 10%

'Protective discrimination' means the progressive grading of sizes/tripping times of:

Line fuses and overcurrent relays
Magnetic and thermal current transformers.
440 V and 220 V transformers.
Generators and motors.

The earth lamps in a 3-phase system indicate as follows: Red= bright Yellow= dark Blue= dim

no fault - hard earth - light earth
light earth - no fault - hard earth
light earth - hard earth - no fault
hard earth - light earth - no fault

Choose the group of electrical power supplies that best fits the identification of 'Emergency'

Batteries and No 1 diesel
No 1 diesel and No 2 diesel
Shaft generator and emergency diesel
Emergency diesel and batteries

The insulation resistance (IR) to earth of a new galley hot-plate is measured to be 30 Mohm. When three identical hot-plates are tested together their combined IR will be:

3 Mohm
10 Mohm
30 Mohm
90 Mohm

An electrical power emergency source in a ship is required because:

It satisfies the SOLAS requirements for ship safety
It satisfies the need to be environmentally 'friendly'
The main diesel generator(s) can be taken out of service for overhaul or repair
The ship's total load can be shared between main and emergency generators

Check-synchroniser equipment is often installed to:

Allow auto-synchronising to take place
Permit faster paralleling
Prevent manual synchronising outside permitted limits
Ensure fair equal sharing between generators

When a blackout occurs: what should be your first reaction?

Cancel audible alarms
Inform the bridge about the reason for blackout, and expected time to restart.
Inform the Chief Engineer
Investigate the cause of the blackout

Due to failure of one of the carbon brushes the excitation voltage is lost on one alternator that is operating in parallel. Will that alternator then:

Completely loose its share of the load causing the auxiliary engine to speed up
Try to take all the load and so trip the main circuit breaker
Overload due to reduced voltage output and increased current
Continue to share the active load (kW) but have very high reactive load (kVAR)

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Marine Electrotechnology. Test 1

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