11 - 28 Flashcards
The voltage output of an AC generator is controlled by:
A) regulating the speed of the prime mover
B) varying the DC exciter voltage
C) Varying the reluctance of the air gap
D) Shorting out part of the armature windings
B) varying the DC exciter voltage
PHEP Ch28 p. 1
The major difference between various voltage regulator systems is merely the method by which…
A) field circuit resistance and current is controlled
B) Armature circuit resistance is controlled
C) Load circuit resistance is controlled
D) Armature current and load resistance is controlled
A) field circuit resistance and current is controlled
PHEP Ch28 p. 40
The voltage held by the vibrating type voltage regulator can be adjusted by:
A) Varying the weight W.
B) Adjusting the tension of the DC solenoid spring
C) varying the weight W and adjusting the tension of the DC solenoid spring
D) Adjusting the action of the oil dash-pot
C) varying the weight W and adjusting the tension of the DC solenoid spring
PHEP Ch28 p. 5
All of the following statements concerning the rheostat type voltage regulator are true except for:
A) The torque motor is mechanically linked to the rheostat element
B) Any movements of the torque motor will cause the resistance value of the rheostat element to change
C) The secondary winding of the damping transformer is connected in series with the torque motor coil and the rectifier
D) the primary purpose of the exciter field is to adjust the generator output voltage
D) the primary purpose of the exciter field is to adjust the generator output voltage
Wide-range excitation control is sometimes provided for in voltage regulator arrangements for large generators using separately excited main exciters by using a:
A) Wheatstone bridge rheostat
B) Hand-operated rheostat
C) Tilting plate rheostat
D) Rocking disk rheostat
A) Wheatstone bridge rheostat
PHEP Ch28 p. 16
When the regulator control switch for the amplidyne voltage regulator is in the ON position, the effect is to:
A) Reduce the exciter field current
B) Lower the exciter voltage
C) Decrease the field current and terminal voltage of the AC machine
D) All three of the above
D) all three of the above
PHEP Ch28 p. 23
In order to provide for proper division of reactive current between AC generators operating in parallel, their voltage regulators incorporate a scheme called…
A) Line-drop comprnsatio
B) cross-current compensation
C) Reactive-load supervising
D) the 120 degree CT connection
B) cross-current compensation
PHEP Ch28 p. 31
Of the following statements concerning synchonous condensers, which one is not true:
A) A strong field will produce VARs and raise the voltage
B) A weak field will consume VARs and lower the voltage
C) The excitation range is maintained less than that for AC generators to prevent loss of synchronism
D) Synchronous condensers operating in parallel may incorporate cross-current compensation in their voltage regulator scheme
C) the excitation range is maintained less than that for AC generators to prevent loss of synchronism
PHEP Ch28 p. 35
In the rheostat type voltage regulator, when the terminal voltage of the AC generator starts to fall the action of the torque motor:
A) Opens the circuit to the rectifier
B) short-circuits more of the high resistance plates
C) short-circuits less of the high resistance plates
D) Completes the circuit to the rectifier
B) short-circuits more of the high resistance plates
PHEP Ch28 p. 7
System stability can be maintained and a faster time-response to load changed obtained by using voltage system regulators equipped with…
A) Both a feed back control system and an electrically controlled separate motor
B) Only a shaft driven rotation machine
C) Line-drop compensation
D) Cross-current compensation
A) both a feed back control system and an electrically controlled separate motor
PHEP Ch28 p. 36
