AC Power Distribution Systems (Ch.3)⛔️

Question 1

What is the function of the switchboard bus ties?

Answer 1

To allow power distribution direct from the generator to the load

Question 2

On small ships, locating distribution panels centrally with respect to the load and feeding them directly from the generators has which of the following advantages?

Answer 2

Simplifies installation
Reduces weight and space requirements
Reduces equipment requirements

Question 3

What information is contained in circuit information panels located on distribution panels?

Answer 3

The circuit number, the name of circuit controlled, space served

Question 4

You are troubleshooting a circuit and you want to know the max allowed current. This information is marked on which of the following plates?

Answer 4

Cable identifications plate

Question 5

For what reason is the phase sequence important to the distribution system aboard ship?

Answer 5

The phase sequence determines the direction of rotation of three phase motors

Question 6

What is the advantage of using an MBT as an alternate power source to a vital load?

Answer 6

The load can be secured faster in an emergency

Question 7

What service is provided by bus transfer equipment?

Answer 7

Two sources of power to equipment that is vital to the ship

Question 8

Aboard ships, switchgear groups are physically separated as much as practical for what reason?

Answer 8

To afford greater protection from damage during battle

Question 9

Which of the following is NOT a function provided by switchboards aboard ships?

Answer 9

Automatic shifting of power to alternate sources if normal power is lost

Question 10

What is the purpose of the disconnect links?

Answer 10

They enable repairs to be conducted to one switchboard without affecting the operation of the whole system

Question 11

If lamp A is out when S is open, what problem is indicated?

Answer 11

Phase A is grounded

Question 12

What indication is given if lamp acid dim when switch S is closed?

Answer 12

Phase C has a ground

Question 13

The output of all AC generators is generated in what winding?

Answer 13

The armature winding

Question 14

Revolving armature generators are seldom used for what reason?

Answer 14

They are subject to arc over at high voltages

Question 15

When dealing with the load rating of AC generators, what factor must be accounted for?

Answer 15

The internal heat the generator can withstand

Question 16

Which of the following statements defines the term power factor?

Answer 16

The expression of the losses within the electrical distribution system

Question 17

AC generator sets may be divided into what two classes?

Answer 17

Low speed, engine driven and high speed, turbine driven

Question 18

What function is provided by AC generator excites?

Answer 18

DC to the load

Question 19

The rotary force used to provide the rotating action in generators may be supplied by which of the following prime movers?

Answer 19

Each of the above

Question 20

What is the magnitude of the voltage across any two phases?

Answer 20

Larger than the voltage across a single phase

Question 21

When you use vectors to analyze AC circuits, what rotation direction represents (a) positive and (b) negative polarity?

Answer 21

(A)counterclockwise

(B)clockwise

Question 22

In a purely capacitive circuit, what is the relationship between voltage and current?

Answer 22

Voltage and current are in phase

Question 23

A generator is operating at 450v AC, 60hertz, supplying a load of 1000amps and 306,000 watts. What is the power factor?

Answer 23

?????

Question 24

When the phase voltage is 100v in a delta connected AC generator, what is the line or load voltage?

Answer 24

173V

Question 25

When the phase current in a balanced delta connector is 20amps, what is the line current?

Answer 25

20amps

Question 26

The output frequency of an AC generator varies directly with which of the following generator characteristics?

Answer 26

Number of poles on rotor

Speed rotation of rotor

Question 27

The line voltage of a eye-connected stator with a balanced load isnt twice the phase voltage for what reason?

Answer 27

The loads seen by the generator are usually inductive

Question 28

at which of the following points will a generator’s output voltage increase?

Answer 28

When the rotating field strength increases

Question 29

A decrease in general terminal voltage caused by an inductive load is partly the result of which of the following actions?

Answer 29

Reduced DC field flux caused by the opposing action of the armature mmf

Question 30

The most practical method to control voltage of an AC generator is to regulate the generator’s speed.

Answer 30

True

Question 31

In transformers, electrical energy is transferred from one circuit to another through which of the following actions?

Answer 31

Electromagnetic induction

Question 32

When a transformer transfers electrical energy, what elements are either increased of decreased by the transformer?

Answer 32

Current and voltage only

Question 33

In a transformer, what winding is designated as the primary?

Answer 33

The one with the highest voltage

Question 34

Which of the following systems makes up the power distribution system?

Answer 34

Casualty power system
Emergency power system
Ship’s service system