Power & Distribution Flashcards
how many diesel generators are fitted to a distribution system
four
what does EDC stand for
Electrical distribution centre
how many EDC’s are fitted to a distribution system
four
What does MCCB stand for
moulded case circuit breaker
list the 5 main breakers fitted to a distribution system
- supply breaker
- shore/supply breaker
- busbar linking breaker
- interconnector
- feeder breaker
what is the power book
shows the distribution for all 440v services
what is the lighting book
- includes low power
- shows postcode / layout for lighting circuits
- 115v/230v
what is the reference books
books provide images and information covering the ships systems and equipment fitted
what is the ratio for 440v fuses
(fuse discrimination)
3:1
what is the ratio for 115v fuses
(fuse discrimination)
2:1
explain breaker discrimination
- First breaker to trip is the MCCB
- Last breaker to trip is the supply breaker (otherwise all power will go out)
- Breaker nearest the fault is the first to trip
- Breaker furthest from the fault is the last to trip
(kettle wont trip a generator)
what does MCR stand for
machinery control room
What does PCP stand for
primary control position
What does SCP stand for
secondary control positions
what are the three basic items that a distribution system needs
prime mover
generator
switchboard
list the meters fitted to a switchboard generator section
6 in total
- voltmeter
- ammeter
- kw meter
- frequency meter
- syncroscope
- earth meter
where are breaker operating switches found and what are they called
- dicrepency switch
- located in pcp
describe the connection of shore supply
what are the rules regarding eathing the ship when connecting shore supply
- ship must be earthed to either the jetty or ship along side
- by at least 2 points, not less then half the ships length
- ganway needs to be earthed
what is used to confirm correct phase rotation
- the phase sequence indicator (2 lamps)
- the right one should be brighter
what would happen to a motor if phase rotation is wrong
motors would run backwards
list 3 types of hand changeover switches
- normal/alternative
- normal/emergancy
- normal/alternative/emergancy
list 3 kinds of changeover switches
- ACOS
- HCOS
- ROCOS
what & where are the 440v earth testing facilities found
- earth indicator light located on the switchboard
- some also have audible alarms
why are there seperate 115v testing facilities
115v is a transformed supply and the secondary winding (output side) is not physically connected to the primary wiring
what does C&C stand for
control and communications (switchboard)
define what a converted supply is
has its voltage and/or frequency changed from 450v, 60Hz
what are the main voltage & frequency used in the C&C switchboard
- 24v DC
- 115v, 400HZ
what are the 2 catagories for batteries
- primary
- secondary
what are the characteristics of the 2 batteries
primary - dry - not rechargable, usually small
secondary - wet - rechargeable, vary in sizes
how many diesels generators are fitted to a type 23
four
what is the output of the generators fitted to a type 23
- 600v
- 61.2HZ
- 62.3 phase
- 63.13mw
why do we produce the 600V for a type 23
440v system would not have given a large enough range of speed
what are the 7 breakers fitted to a type 23 P&D system
- generator supply breaker
- interconnector breaker
- shore supply breaker
- electric motor air circuit breaker
- motor generator feeder breaker
- motor generator supply breaker
- 450v supply breaker
what does the converter regulator do
converts and regulates the voltage at 750v DC
what is the voltage required for the ships services and how is it produced
the 450v required for ships services is generated by a motor generator
what are EDC’s and many types are fitted
electrical distribution panels
there are 3 types
