Which of the following motor is preferred for automatic drives?
Ward Leonard controlled dc motors
Squirrel cage induction motor
Synchronous motors
Q.3.
In motoring mode slip s
greater than 1 and less than2
greater than 0and less than1
negative
none of the above
Q.4.
Field control method is
constant power drive
constant torque drive
variable torque and power drive
constant torque and power drive
Q.5.
Armature Voltage control gives speed control
below base speed
above base speed
near 0 speed
near maximum possible speed
Q.6.
DUTY cycle k for DC TO DC CONVERTOR has maximum and minimum value as
1 and 0
0 and 1
0 and 0
1 and 1
Q.7.
Firing angle range in conversion mode Q1 operation is
0 to 90
90 to 180
0 to 360
180 to 270
Q.8.
Steady state equilibrium point means operating conditionat which
LOAD TORQUE= MOTOR TORQUE
LOAD TORQUE GREATER THAN MOTOR TORQUE
LOAD TORQUE LESS THAN MOTOR TORQUE
NONE of the above
Q.9.
Fan is example of
CONSTNT Torque load
CONSTNT POWER load
torque varies as square of the speed
speed varies as square of the torque
Q.10.
IN Regeneration mode, power flow is from
Load to Source
Source to load
Q.11.
FORWARD MOTORING mode gives
positive power
negative power
Q.12.
In electric train which motor is used
DC Series MOTOR
DC Shunt MOTOR
INDUCTION MOTOR
SYNCHRONOUS MOTOR
Q.13.
Introducing the external resistance decreases(i) speed (ii) output power (iii) starting torque
(iii)
(ii),(iii)
(i),(ii)
(i), (ii), (iii)
Q.14.
The concept of V/f control of inverters driving induction motors resuls in
constant torque operation
speed reversal reduced
magnetic loss
hormonic elimination
Q.15.
Which type of braking can be used for saving energy?
dynamic
plugging
regenerative
Q.16.
What is the expression for load voltage when the chopper is operated in the second quadrant?
Vs
E
0
E + Ldi/dt
Q.17.
The field of an induction motor rotor rotates relative to the stator at
a) Rotor speed
b) Synchronous speed
c) Slip speed
d) Very low speed
Q.18.
The drawback of speed control of a slip ring induction motor with the help of resistance in the circuit is that
a) It is applicable only to motors having power of more than 100 kW
b) It results in high losses
c) With reduction in speed, the torque decreases significantly
d) The speed can be controlled only very broadly
Q.19.
In regenerative braking of dc shunt motor
Eb=V
Eb<V
Eb>V
None of the above
Q.20.
In cumulatively cascade method for speed controlling, if PA is the number of poles of main motor and PB is the number of poles of auxiliary method. Then the speed of the rotor B is given
120f / PA + PB
120f / PA - PB
120f / PA
120f / PB
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