AC Distribution

Question 1

Split Bus System

Answer 1

Constant 400hz generators
Not parallel so phases do not need to match
Not designed to connect in parallel

Question 2

Generator fail on split bus system

Answer 2

Bus bar can be supplied by one generator via busbar tie breakers

Question 3

AC Distribution Parallel

Answer 3

Generators are on the same busbars. Full load sharing
3 phases need to be synced
Same frequency
Same voltage
Same phase

Question 4

Generator Control Unit (GCU)

Answer 4

Fault sensed GCU opens the generator circuit breaker
Exciter control breaker tripped
Generator disconnected from it bus bar and prevented from producing electricity

Question 5

Generator Control unit protection against

Answer 5

Ac generator over voltage
AC generator under voltage
Under frequency
Over speed
Excess current
Differential fault

Question 6

Load Sharing

Answer 6

Control needed to ensure equal share of load

Real load + reactive load

Question 7

Load Sharing Real Load is

Answer 7

Is the actual working load output - real power
Direct related to mechanical power supplies to alternator drive
CSDU or engine

Question 8

Real Load Sharing is achieved by

Answer 8

Controlling the CSDU and adjusting the torque at its output shaft

Question 9

Load Sharing - Reactive Load

Answer 9

Sum of inductive and capacitive currents and voltages expressed in kVAR

Question 10

Reactive Load Sharing is achieved by

Answer 10

Controlling voltage output of each generator connected in parallel
Voltages identical reactive loads on each generator will be the same

Question 11

Load Shedding

Answer 11

Reducing services when alternator failed

Question 12

Split Bus system

Answer 12

Each generator feeds it own bus run independently

Question 13

Parallel bus systems

Answer 13

Generators can be connected to the same bus

Question 14

What happens in a split bar generator failure

Answer 14

Generator is cut off from it load bus
Bus tie breaker closes
Working generator able to feed to both load buses
APU can then take over

Question 15

Generator failure in a parallel bus system

Answer 15

Generator cut off from system
Load busses will be fed from remaining generators connected to it.

Question 16

Parallel Generators

Answer 16

Frequency/Voltage and phase sequence are the same
Not required on engine start though

Question 17

Generator Control Unit

Answer 17

GCU automatically opens generator circuit breaker
Will trip exciter control breaker/relay

Generator disconnected from bus bar and prevented from producing electricity

Question 18

GCU provides protection for

Answer 18

AC generator over voltage
AC generator under voltage
Under frequency
High frequency
Excess current
Differential faults

GCU connected to each generator and has direct input from fire handle

Question 19

Real load sharing is achieved by

Answer 19

Controlling the constant speed drive unit

Question 20

Reactive load sharing

Answer 20

Achieved by controlling the voltage output