AC Power Supply Systems

Question 1

Twin freq wild system

Answer 1

Comes form 2 engines

2 separate bus bars

Question 2

Constant freq systems can be subdivided into

Answer 2

Spilt busbar systems

Parallel busbar systems

Question 3

Before external power can be applied it is checked for

Answer 3

Correct voltage
Correct freq (400Hz)
Correct freq ABC
No other power sources feeding AC busbar (dead busbar sensing)

Can’t have ships power and external power

Question 4

GCU houses

Answer 4

Generator control unit

Houses - voltage regulator,freq control, protection circuits

Question 5

Differential protection

Answer 5

Hoops transformers will isolate the AC generators if the differential fault occurs - gets grounded

Question 6

GCB

Answer 6

Connects generator to its individual busbar

Big switch, mechanically latched

Question 7

BTB

Answer 7

Bus tie breakers - tie each busbar to each other - connects them together

Question 8

GFR

Answer 8

Generator field relay - generates current to the exciter - generator on/off switch

Question 9

Spilt busbar has no paralleling

Answer 9

AC power

Source of the system does not enter automatically - when it reaches the correct voltage and frequency - must be manually switched on

Question 10

Spilt busbar system - what takes priority

Answer 10

Source AC power being connected to a generator bus takes priority