Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

SKT Book 2 > B2U3 Alternators, Controls, And Protective Devices > Flashcards

B2U3 Alternators, Controls, And Protective Devices Flashcards

1
Q

What are the two distinct poles every magnet has?

A

(1) A North Pole.

(2) A south pole.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the magnetic lines of force?

A

Invisible lines of magnetic force that exist between the poles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What materials make up one very good type of permanent magnet?

A

An alloy of aluminum, nickel, and cobalt.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What three things are required for the generation of AC?

A

(1) A magnetic field.
(2) Conductors.
(3) Relative motion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens when the magnetic field is at 90 degrees during the generator of voltage?

A

The greatest number of magnetic lines of force cut the conductor causing the voltage to peak.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens as the rotation of the north pole of the magnet reaches 225 degrees?

A

The magnetic lines of force begin to cut the conductor again. This time the lines of force move in the opposite direction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is an exciter?

A

A device that provides the alternator electricity needed to produce the electricity you use to operate equipment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the armature?

A

The rotating conductor of the exciter.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the rotor assembly?

A

A device that provides the magnetic field necessary to produce electricity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the purpose of the interpoles?

A

They offer a slight magnetic force that aligns the main magnetic field so it remains most effective.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the biggest difference between the self-exciting and permanent magnetic voltage regulator?

A

The permanent magnetic voltage regulator uses a permanent magnet; the self-exciting voltage regulator uses a soft iron core.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why do most exciters use soft iron cores?

A

Because they retain residual magnetism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens if the voltage level of an alternator begins to drop?

A

The voltage regulator senses the lower than normal level and increases the current to the exciter field windings.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens if you turn the voltage adjustment down?

A

This lowers the reference voltage making the voltage regulator read the output voltage level as too high.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the output of a single set of stator coils on an alternator?

A

There will be a single output voltage induced by the magnetic field.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Since the alternator works over 360 degrees and there are three different phases, how far do they sit?

A

120 degrees apart.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Since there are three legs that all connect in the middle in a wye connected alternator, how many connection points are there?

A

Four

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is an indication of a shorted diode?

A

Low reading in both directions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is used to attach the leads to the diodes?

A

Soldering iron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is used to test the main rotor leads?

A

Multimeter set to ohms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What do you attach the overhead hoist to when lifting the alternator assembly?

A

Lifting eye.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why do you often use one voltmeter connected to a selector switch?

A

To avoid the expense of having a separate voltmeter for each phase of a three-phase alternator.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Why should you never open the secondary winding of a current transformer while the switchgear is energized?

A

Because of the very high buildup of voltage.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the change in the relationship of current and voltage in a purely resistive load?

A

Current and voltage are in phase, and the phase angle is 0.

25
Q

What do switches provide for us?

A

On-off control of the circuit that the switch is associated with.

26
Q

If your generator uses isolation dampeners, what do you inspect them for?

A

Cracking and deterioration.

27
Q

What is the first step to replacing an exciter?

A

Tagging and removing the wiring from the rectifier assembly.

28
Q

What will typically secure the adjustment knob?

A

A setscrew.

29
Q

When does a magnetic-type circuit breaker respond to trip?

A

Instantaneously when an excess of current flows through the breaker.

30
Q

What affects the strength of the magnetic force exerted on the armature?

A

(1) The number of wire windings.
(2) The size of the conductors.
(3) The amount of current applied.

31
Q

What makes SSRs far more reliable than inductive relays?

A

They have no moving parts.

32
Q

When selecting fuses, what must you consider as to which fuse to install?

A

Total current flow and voltage of the circuit.

33
Q

What is the function of an arc chute that surrounds each set of arc (not main) contacts?

A

To extinguish or quench any arcing that takes place when the breaker opens or closes.

34
Q

What does the closing assembly usually contain?

A

A closing coil or motor and a control switch.

35
Q

What is the relay equipped with to align the coil and contact pins to the base?

A

Keyway

36
Q

Where does a magnet have the greatest amount of magnetism?

a. In the center.
b. At the north pole.
c. At the south pole.
d. At each end of the magnet.

A

D. at the end of each magnet

37
Q

What is the small amount of magnetism that remains in an item after removing the magnetic field?

a. Faint.
b. Residual.
c. Reluctant.
d. Specialized.

A

B. Residual

38
Q

Which alternator component offers a slight magnetic force that aligns the main magnetic field so it remains most effective?

a. Rotor.
b. Interpoles.
c. Voltage regulator.
d. Damping windings.

A

B. Interpoles

39
Q

Which alternator component helps the generator maintain a stable voltage under varying load conditions?

a. Rotor.
b. Interpoles.
c. Stator.
d. Damping windings.

A

D. Damping Windings

40
Q

What type of cores do most exciters use that retain residual magnetism?

a. Galvanized.
b. Soft iron.
c. Mica.
d. Air.

A

B. Soft iron

41
Q

What does a voltage regulator sense if it decreases the current to the exciter field windings causing the magnetic field to get weaker?

a. A drop in the load.
b. A drop in the current.
c. An increase in the frequency.
d. An increase in the voltage level.

A

D. An increase in the voltage level

42
Q

Which type of alternator consists of a rotating magnetic field and a single set of stator coils?

a. Wye.
b. Delta.
c. Three phase.
d. Single phase.

A

D. Single Phase

43
Q

Which alternator configuration has three legs that all connect in the middle?

a. Wye.
b. Beta.
c. Delta.
d. Gamma.

A

A. Wye.

44
Q

What is the multiplier you use to determine the line voltage if you know the phase voltage?

a. .707.
b. 1.73.
c. 2.00.
d. 3.14.

A

B. 1.73

45
Q

Which alternator configuration has no neutral that is common to all three phases?

a. Wye.
b. Beta.
c. Delta.
d. Gamma.

A

C. Delta

46
Q

In a rotating rectifier test, what does it indicate if a diode has a low reading in both directions?

a. Open.
b. Closed.
c. Shorted.
d. Reversed.

A

C. Shorted

47
Q

Which test instrument do you use when testing the main rotor leads?

a. Voltmeter.
b. Ammeter.
c. Ground tester.
d. Multimeter set to ohms.

A

D. Multimeter set to ohms.

48
Q

Which component is used with a voltmeter for a three-phase alternator to save money?

a. Multi-tap transformers.
b. Multiple pointers.
c. Cheaper meters.
d. Selector switch.

A

D. Selector switch

49
Q

Which meter indicates the true power load in an alternating current (AC) circuit?

a. Ammeter.
b. Voltmeter.
c. Wattmeter.
d. Power factor meter.

A

C. Wattmeter

50
Q

On the power factor meter, what will an inductive load cause?

a. Current and voltage in phase.
b. Current to lead voltage.
c. Current to lag voltage.
d. Will have no effect.

A

C. current to lag voltage

51
Q

What devices provide variable amounts of resistance to provide a circuit with different levels of output?

a. Rheostats.
b. Inductors.
c. Capacitors.
d. Selector switches.

A

A. Rheostats

52
Q

When you inspect the voltage regulator vibration dampeners, look for

a. cracking and deterioration.
b. security and discoloration.
c. lubrication and dry rot.
d. staining and wear.

A

A. Cracking and deterioration

53
Q

Where should you look for any signs of rubbing on an exciter?

a. At the diode ring.
b. Around the bearing.
c. Between the rotor and stator.
d. Where the shaft meets the diode.

A

C. Between the rotor and the stator

54
Q

What color will a transformer turn if it gets too hot?

a. Bright red.
b. Dark gray or black.
c. Lighter than normal.
d. Shade of yellow or brown.

A

A. Bright Red.

55
Q

Which type of circuit breaker responds instantaneously when an excess of current flows through the breaker?

a. Coil.
b. Heat.
c. Magnetic.
d. Secondary trip.

A

C. Magnetic

56
Q

Which relay component provides a constant restraining force keeping the armature in the normal (deenergized) position?

a. Coil.
b. Spring.
c. Plunger.
d. Contact.

A

B. Spring

57
Q

Which relay component is completely self-contained and has no moving parts?

a. Capacitive.
b. Solid-state.
c. Inductive.
d. Isolation.

A

B. Solid-state

58
Q

The closing assembly of a circuit breaker usually consists of

a. arc chutes and a tripping coil.
b. advancing motor and distribution points.
c. closing coil or motor and a control switch.
d. closing transformer and adjustable resistors.

A

C. Closing coil or motor and a control switch.

59
Q

Which ohmmeter reading indicates that a fuse is good and no further testing is necessary?

a. Zero.
b. Infinity.
c. Below 250 ohms.
d. Above 500 ohms.

A

A. Zero

SKT Book 2 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions