Q.1
Which of the braking system is used in industries
  • Plugging braking
  • Dynamic braking
  • Regenerative braking.
Q.2
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
0 h : 0 m : 1 s