Electrical level 3 Lt. M1-M2 questions |\ |\ |\ |\ |\ |\
with answers |\
Give the two main reasons for preferring revolving-field alternators
|\ |\ |\ |\ |\ |\ |\ |\ |\
to revolving-armature alternators. - CORRECT ANSWERS ✔✔1.
|\ |\ |\ |\ |\ |\ |\
Higher voltages generated
|\ |\ |\
2. Higher currents can be conducted to the load
|\ |\ |\ |\ |\ |\ |\ |\
What is the purpose of an exciter? - CORRECT ANSWERS ✔✔To
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
supply DC to alternator field circuit
|\ |\ |\ |\ |\
Explain the construction differences between a salient-pole rotor
|\ |\ |\ |\ |\ |\ |\ |\
and a cylindrical rotor. - CORRECT ANSWERS ✔✔Salient pole
|\ |\ |\ |\ |\ |\ |\ |\ |\
rotor, larger diameter, pole pieces protruding
|\ |\ |\ |\ |\
Cylindrical smooth faced |\ |\
What is the purpose of a field-discharge resistor? - CORRECT
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔Eliminate inductive back voltage created by opening
|\ |\ |\ |\ |\ |\ |\ |\
field circuit
|\
, Give two reasons why a brushless exciter may be selected over a
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
brush-type exciter for the field of an alternator. - CORRECT|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔1. When explosive or wet ambient conditions exist |\ |\ |\ |\ |\ |\ |\ |\
2. When it is necessary to have low maintenance
|\ |\ |\ |\ |\ |\ |\ |\
Name two factors that control the frequency output of an alternator.
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
- CORRECT ANSWERS ✔✔1. Rotor speed
|\ |\ |\ |\ |\ |\
2. Number of field poles
|\ |\ |\ |\
The output voltage of an alternator is maintained at a steady level
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
through the use of a(n)? - CORRECT ANSWERS ✔✔Automatic
|\ |\ |\ |\ |\ |\ |\ |\ |\
voltage regulator |\
The voltage regulation of an alternator will be poorest with a
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
__________ (high/low) power factor load. - CORRECT ANSWERS |\ |\ |\ |\ |\ |\ |\ |\
✔✔Low 0% |\
What are the three main reasons for connecting a three-phase
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
alternator in wye? - CORRECT ANSWERS ✔✔1. To obtain two|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
different voltages (Phase and line) |\ |\ |\ |\
2. Insulation requirements are reduced to phase values
|\ |\ |\ |\ |\ |\ |\
3. Provides neutral point for ground system
|\ |\ |\ |\ |\ |\
with answers |\
Give the two main reasons for preferring revolving-field alternators
|\ |\ |\ |\ |\ |\ |\ |\ |\
to revolving-armature alternators. - CORRECT ANSWERS ✔✔1.
|\ |\ |\ |\ |\ |\ |\
Higher voltages generated
|\ |\ |\
2. Higher currents can be conducted to the load
|\ |\ |\ |\ |\ |\ |\ |\
What is the purpose of an exciter? - CORRECT ANSWERS ✔✔To
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
supply DC to alternator field circuit
|\ |\ |\ |\ |\
Explain the construction differences between a salient-pole rotor
|\ |\ |\ |\ |\ |\ |\ |\
and a cylindrical rotor. - CORRECT ANSWERS ✔✔Salient pole
|\ |\ |\ |\ |\ |\ |\ |\ |\
rotor, larger diameter, pole pieces protruding
|\ |\ |\ |\ |\
Cylindrical smooth faced |\ |\
What is the purpose of a field-discharge resistor? - CORRECT
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔Eliminate inductive back voltage created by opening
|\ |\ |\ |\ |\ |\ |\ |\
field circuit
|\
, Give two reasons why a brushless exciter may be selected over a
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
brush-type exciter for the field of an alternator. - CORRECT|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔1. When explosive or wet ambient conditions exist |\ |\ |\ |\ |\ |\ |\ |\
2. When it is necessary to have low maintenance
|\ |\ |\ |\ |\ |\ |\ |\
Name two factors that control the frequency output of an alternator.
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
- CORRECT ANSWERS ✔✔1. Rotor speed
|\ |\ |\ |\ |\ |\
2. Number of field poles
|\ |\ |\ |\
The output voltage of an alternator is maintained at a steady level
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
through the use of a(n)? - CORRECT ANSWERS ✔✔Automatic
|\ |\ |\ |\ |\ |\ |\ |\ |\
voltage regulator |\
The voltage regulation of an alternator will be poorest with a
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
__________ (high/low) power factor load. - CORRECT ANSWERS |\ |\ |\ |\ |\ |\ |\ |\
✔✔Low 0% |\
What are the three main reasons for connecting a three-phase
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
alternator in wye? - CORRECT ANSWERS ✔✔1. To obtain two|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
different voltages (Phase and line) |\ |\ |\ |\
2. Insulation requirements are reduced to phase values
|\ |\ |\ |\ |\ |\ |\
3. Provides neutral point for ground system
|\ |\ |\ |\ |\ |\
