Oral Electrical questions

Question 1

Explain how you would parallel two generators and load share.

Answer 1

a

Question 2

What is the frequency of the incoming generator?

Answer 2

a

Question 3

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?

Answer 3

. (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

Question 4

Why would you send the crew member to the hospital after an electric shock?

Answer 4

Examiner not only wanted to hear about the ecg, but also wanted to know how an electric shock can cause defibrillation.

Question 5

How can you detect an earth fault?

Answer 5

Using the earth leakage lights

Question 6

How do you find an earth fault?

Answer 6

A systematic approach of elimination

Question 7

Explain how a RCD works

Answer 7

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.

Question 8

Why do you have RCDs aboard a DCV?

Answer 8

To protect life

Question 9

Why don’t you have them on big ships (RAVs)?

Answer 9

Insulated neutral

Question 10

How do you isolate an electric motor?

Answer 10

Risk assessment

electrical permit

Question 11

Would you obtain an electrical isolation permit to isolate an electrical motor?

Answer 11

Yes

Question 12

The incoming generator isn’t taking any load, what do you do?

Answer 12

. (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)…

Question 13

How do you electrically isolate the generator?

Answer 13

a

Question 14

How do you test your multimeter when checking electrical isolation?

Answer 14

a

Question 15

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?

Answer 15

No

Question 16

Why have a Residual Current Device as well as fuses and breakers?

Answer 16

RCD to protect life

Fuses and breakers to protect equipment

Question 17

Which switchboard supplies power for battery charging

Answer 17

Emergency bus

Question 18

General arrangements of switchboards

Answer 18

Candidate had 2 diesel alternators to main switchboard, two bus ties to emergency switchboard with emergency diesel alternator ready to supply this board

Question 19

What are the immediate checks you would do once 2 generators are synchronised?

Answer 19

Volts
hetz’s
load distribution

Question 20

Briefly explain how earth lamps work.

Answer 20

a

Question 21

When disconnecting an electric motor, what wire do you disconnect last?

Answer 21

(Examiner wanted to hear “earth wire”.)

Question 22

How do you leave the electrical connections after disconnecting an electric motor?

Answer 22

1. Sealed and covered
2. Information tag as to where the isolation has be carried out
   3.

Question 23

On a large electric motor, what other considerations about it regarding isolation?

Answer 23

It could have a separate circuit for motor heating – this will need to be isolated and disconnected

Question 24

What services does the emergency switchboard supply?

Answer 24

a

Question 25

How long should the emergency supply last for?

Answer 25

My vessel 3 hours

Candidate answered “18 hours for a general vessel and 36 hours for a passenger vessel”.

Question 26

What is an AVR and what does it do?

Answer 26

Automatic voltage regulator, and it supplies DC current to the generator exciter stator to control the generator out put.