Ship Service Switchboard

Front 1

What are type ACB circuit breakers used for?

Back 1

- to connect ship’s service and emergency generators to the power distribution system, bus ties, shore connection circuits, and some feeder circuits from the ship’s service

-normally applied where heavy loads and high short-circuit currents are available.

Front 2

What is the formula for apparent power factor?

Back 2

=current * voltage *1.73/1000

power factor = kW/kVA

Front 3

What is kW?

Back 3

True power as read on the wattmeter

Front 4

When working on draw-out circuit breakers, make sure __________

Back 4

they are switched to the open position.

Front 5

Modern circuit breakers have contacts coated with _________________

Back 5

silver, silver and cadmium oxide, or silver and tungsten

Front 6

What should you clean silver contacts on circuit breakers with?

Back 6

inhibited methyl chloroform or a fine file with sandpaper No 00

Front 7

What does the red switchboard light indicator mean?

Back 7

Danger or emergency condition requiring

immediate attention or corrective action

Front 8

What does the green switchboard light indicator mean?

Back 8

Normal Condition

Front 9

What does the white switchboard light indicator mean?

Back 9

Power available or power on

Front 10

What does the blue switchboard light indicator mean?

Back 10

Closed, advisory circuit

Front 11

What does the clear switchboard light indicator mean?

Back 11

Synchronizing or ground detector lights

Front 12

What does the yellow switchboard light indicator mean?

Back 12

Abnormal, but not requiring immediate attention

Front 13

A meter movement is:

Back 13

- The part of a meter that moves.

- A meter movement converts electrical energy into mechanical energy.

Front 14

What is a permanent-magnet moving-coil movement?

Back 14

based upon a fixed permanent magnet and a coil of wire that is able to move.

Front 15

What is the basic movement in most measuring instruments?

Back 15

- permanent-magnet moving-coil meter movement

- also known as the d'Arsonval movement

Front 16

In order to use a d'Arsonval meter (or permanent-magnet moving-coil) what must the circuit be?

Back 16

- Either rectified AC ( at effective value or rms value) or DC with the correct polarity lined up

- Only works in one direction

Front 17

In what meter is there a moving coil, to which the meter pointer is attached, suspended

between two field coils and connected in series with these coils?

Back 17

electrodynamic meter

Front 18

Which meter is most known for using the electrodynamic meter movement?

Back 18

wattmeter

Front 19

What is the most commonly used movement for AC meters?

Back 19

Moving Vane/Iron Meter Movement

Front 20

On what principle does the moving vane meter operate on?

Back 20

magnetic repulsion between like poles

Front 21

Which meter movements use the heating effect of current flowing through a resistance to cause meter deflection?

Back 21

Thermocouple and Hot-wire meter movements

Front 22

Switchboard ammeters and portable ammeters for use primarily on AC are usually of the __________?

Back 22

Moving-iron/vane type

Front 23

Ammeters for use on AC may be either:

Back 23

- Moving-iron/vane

- Electrodynamometer

Front 24

The secondary of a current transformer should never be _________ while the primary is carrying current.

Back 24

open

Front 25

The secondary of a current transformer should always be _______ when not connected to a current coil.

Back 25

short circuited

Front 26

Current measuring instruments, shunts, and primaries of current transformers must always be connected in _________ with the line carrying the current to be measured.

Back 26

series

Front 27

Both DC and AC voltmeters determine voltage by ________

Back 27

measuring current

Front 28

Voltmeters for DC only are almost invariably of the ___________

Back 28

permanent-magnet moving-coil type

Front 29

Switchboard and portable voltmeters primarily for AC are usually ______________

Back 29

moving iron/vane type

Front 30

Potential transformers are designed for a rated secondary voltage of _______ and for primary voltages ranging from ______________

Back 30

110 volts

230 to 6,600 volts.

Front 31

Voltmeters and potential coils of wattmeters

are connected either _____________

Back 31

across the voltage to be measured or to the secondary of a potential transformer (PT).

Front 32

Never short-circuit the secondary of _________

Back 32

a potential transformer

Front 33

Wattmeters are used to indicate _____, not including _____

Back 33

true power, reactive power

Front 34

The power actually being used in a circuit is called what?

Back 34

True power

Front 35

Apparent power is:

Back 35

- the total load on the source and is derived by the product of the readings from the voltmeter and ammeter.

- the combination of true power and reactive power

Front 36

In a DC circuit, true power is the product of _______

Back 36

voltage (through the voltmeter) and current (through the ammeter)

Front 37

In an AC circuit, true power is the product of __________

Back 37

voltage (through the voltmeter), current (through the ammeter) and power factor (through the power factor meter)

Front 38

What three parts make of a frequency meter?

Back 38

- Fixed and moving coils

- Fixed coils and moving iron

- Resonant circuits

Front 39

The frequency meter operates on what principle?

Back 39

mutual induction

Front 40

The frequency meter most often uses what type of meter movement?

Back 40

electrodynamometer

Front 41

What is a series resonant circuit made up of?

Back 41

an impedor, which provides a combination of inductance and capacitive reactance, connected in series with the field coil of the meter

Front 42

The power factor formula is

Back 42

useful power/√ (useful power^2+reactive power^2)

Front 43

What is reactive power?

Back 43

inductive and capacitive power in the circuit, serving no purpose but contributing to the load

Front 44

The difference between the two fields should be within _________ for a synchroscope to operate properly

Back 44

2.5 cycles

Front 45

The function of a phase sequence indicator is ________

Back 45

to indicate whether shore power is of correct or incorrect phase sequence prior to connecting

Front 46

The set point of a reverse power relay is commonly set at ______% for a duration of _________ seconds

Back 46

5 percent of rated generator current for a maximum duration of 10 seconds.

Front 47

What does a reverse power relay measure to determine power level?

Back 47

current and power factor but not voltage

Front 48

What is a speed control unit designed to control?

Back 48

The speed of the prime mover (diesel, gas engines, gas turbines, etc)

Front 49

What is the recommended percent drop in speed to maintain prime mover stability?

Back 49

3 to 5 % drop in speed

Front 50

What is isochronous operation?

Back 50

no change in speed with change in load.

Front 51

The droop mode is used for

Back 51

- parallel operation of gens

- Single-prime-mover operation on an infinite bus

Front 52

Sensor frequency in hz =

Back 52

[(number of teeth on speed sensing gear)*rated primer moving speeed rpms]/60

Front 53

What does a synchronizer do?

Back 53

A synchronizer automatically generates a signal to bias the speed of the prime mover of an off-line generator so that its frequency and phase match those of the bus.

Front 54

What four basic sections make up a voltage regulator?

Back 54

- voltage sensing circuit

- power controlling circuit

- parallel compensation circuit (for parallel generator operation)

- printed circuit board.

Front 55

An over voltage condition is defined as what?

An under voltage condition?

Back 55

15% over rated voltage

15% below rated voltage