Oral Electrical questions Flashcards
Explain how you would parallel two generators and load share.
a
What is the frequency of the incoming generator?
a
A crew member advises you that another crew member received an electric shock and has gone to bed to have a sleep. What do you do?
. (Examiner wanted ‘report the situation to the Master, sent the crew member to hospital, electrically isolate the equipment.)
. (As a WHS/OHS inspection would be likely, I would isolate but then quarantine the scene to preserve any evidence
Why would you send the crew member to the hospital after an electric shock?
Examiner not only wanted to hear about the ecg, but also wanted to know how an electric shock can cause defibrillation.
How can you detect an earth fault?
Using the earth leakage lights
How do you find an earth fault?
A systematic approach of elimination
Explain how a RCD works
using a coil to detect the current flow in the active and out the neutral, if that is different the coil will detect the difference and trip a switch on the active and neutral circuits.
Why do you have RCDs aboard a DCV?
To protect life
Why don’t you have them on big ships (RAVs)?
Insulated neutral
How do you isolate an electric motor?
Risk assessment
electrical permit
Would you obtain an electrical isolation permit to isolate an electrical motor?
Yes
The incoming generator isn’t taking any load, what do you do?
. (Examiner wanted to hear that the generator would be shut down and isolated.)
. (I would drop the generator off the board to avoid reverse power and investigate before I shut down and isolate – such as can I raise and lower the engine speed?, is the fuel rack jammed, is the governor working correctly and its settings correct, is there a lack of fuel to the engine (choked filter)…
How do you electrically isolate the generator?
a
How do you test your multimeter when checking electrical isolation?
a
After an electric shock, the crew member said he was tired and wanted to go to bed for a rest, would you let the person go to sleep?
No
Why have a Residual Current Device as well as fuses and breakers?
RCD to protect life
Fuses and breakers to protect equipment
Which switchboard supplies power for battery charging
Emergency bus
General arrangements of switchboards
Candidate had 2 diesel alternators to main switchboard, two bus ties to emergency switchboard with emergency diesel alternator ready to supply this board
What are the immediate checks you would do once 2 generators are synchronised?
Volts
hetz’s
load distribution
Briefly explain how earth lamps work.
a
When disconnecting an electric motor, what wire do you disconnect last?
(Examiner wanted to hear “earth wire”.)
How do you leave the electrical connections after disconnecting an electric motor?
- Sealed and covered
- Information tag as to where the isolation has be carried out
3.
On a large electric motor, what other considerations about it regarding isolation?
It could have a separate circuit for motor heating – this will need to be isolated and disconnected
What services does the emergency switchboard supply?
a
