Electrical

Question 1

How do you measure the charge of a lead acid battery?

Answer 1

Use a hydrometer to check the specific gravity
Full = 1.25-1.28
Empty = 1.1

Question 2

What is a battery?

Answer 2

A battery is a DC power storage device made of electro-chemical cells used to provide DC electrical power

Question 3

Why is ventilation important in a battery room?

Answer 3

To prevent buildup of hydrogen

Question 4

Name one publication that deals with the storage of batteries

Answer 4

COSWP Ch20

Question 5

Types of secondary cell batteries (rechargeable batteries)

Answer 5

Lead acid
Alkaline
Lithium-ion

Question 6

Why do we need batteries?

Answer 6

They are used onboard as a backup power supply for essential consumers, where in case of main power failure, they are fed from an emergency source of power
(During time between blackout and emergency generator startup)

Question 7

What does a battery UPS cover?

Answer 7

Fire detection systems
Fixed gas detection systems
Emergency and navigation lights
Alarm and monitoring systems
Radar and ECDIS

Question 8

Battery checks

Answer 8

Check condition and tightness of the cable and battery terminals, nuts and intercell connectors

Question 9

Can lead-acid cells and and alkaline cells be stored together?

Answer 9

No they should never be stored together.
There is a risk of rapid electrolyte corrosion to metalwork and damage to both batteries.

Question 10

Checks on motor when running/starting up? (Already in service (no overhaul))

Answer 10

Earth cables
Loose covers
Condition of fan for damage and dirt

Question 11

Why do we use batteries on ships

Answer 11

We use batteries as a backup for essential machinery

They are fed from an emergency source of power in the event of main power failure.

Question 12

Paralleling generators

Answer 12

PPE, tag out book
Engine local
Engine checks (Pre-heat, CW, LO, Start Air, FO, turning gear) slow turn then turn with air
Start and monitor locally off-load then stop
Go to ECR, have SOP at hand
Switch to manual, select incoming generator, turn on meters, start generator.
Observe Voltage and frequency rise
Voltage should be equal
Adjust frequency up and down 1Hz to prove control
Turn on synchroscope
Adjust governor to get a slow clockwise rotation on synchroscope
Close breaker at 5 to 12
Bring the new generator load up slowly while decreasing load on other
Balance out the load
Wait and monitor
Once satisfied, put back on auto and turn off synchroscope or else it will overheat of run continuously

Question 13

What does a synchroscope measure? And what happens if you try to parallel out of phase?

Answer 13

It measures the phase difference. The engine will try to ‘jump’ to that phase and it will cause catastrophic damage to the engine

Question 14

Main switchboard safeties

Answer 14

Circuit breaker
Fuses
Overcurrent trip
Reverse power trip
Under voltage trip
Overspeed trip
Preferential trip
Earthing

Question 15

Taking generator off load

Answer 15

Before stopping a gen make sure that the load is small enough for one gen to handle.
-Put the selector from auto to manual of gen that going off.
-Use governor to control speed so you can slowly reduce load.
-Monitor the parameters, the frequency will automatically maintain 60hz.
-Once gen has reached safe load level, open the circuit breaker by turning ACB control to open.
-Readjust speed to 60hz
-Check gen that is running is maintaining speed.
-Let gen run idle to cool down.
-Stop engine by turning control knob to stop on switchboard.
-Isolation of prime mover and alternator can now begin.

Question 16

How do we find the source of an earth fault on the switch board

Answer 16

We go through each piece of machinery one by one turning them off and off again and check each time to see if the fault is resolved