Electrical Machines Test Online Exam Quiz
Electrical Machines Test GK Quiz. Question and Answers related to Electrical Machines Test. MCQ (Multiple Choice Questions with answers about Electrical Machines Test
A center ammeter connected to the rotor end circuit of a 6-pole,50 Hz, induction motor makes 45 complete oscillations in a minute. Then the rotor speed and the speed of stator field w.r.t. rotor is?
Options
A : 985, 15
B : 970, 1000
C : 985, 985
D : 985, 970
Choose from the below which can be obtained by the equivalent circuit of an electrical machine?
Options
A : Complete performance characteristics of the machine
B : Temperature coefficients of the machine components
C : Type of protection to be used in the machine
D : Design parameters of the windings
A constant torque variable power drive of induction machine has ___________
Options
A : constant air gap flux.
B : constant slip
C : variable air gap flux, constant slip
D : constant slip, constant air gap flux
Due to the line to ground fault, phase ‘a’ in the induction motor phase supply gets cut, then machine ___________
Options
A : continues to run with excessive supply current
B : continues to run with reduced slip
C : stalls
D : all of the mentioned
Torque-slip characteristic of an induction motor is linear in the smaller slip values, because ___________
Options
A : effective rotor resistance is very large compared to reactance
B : rotor resistance is equal to stator resistance
C : rotor resistance is equal to rotor reactance
D : rotor reactance almost equal to stator reactance
For 3-phase induction motor, as load increases from no load towards the full load, torque _______ slip.
Options
A : increases in proportion to
B : decreases in proportion to
C : remains constant to
D : increases hyperbolically to
A 3-phase induction motor is fed at the stator at a frequency f. If the rotor speed is Nr and synchronous speed is Ns, then the absolute speed of the resultant flux in space is?
Options
A : Ns
B : (Ns+Nr) if the flux rotates in the same same direction as the rotor
C : (Ns-Nr) if the flux rotates in the same same direction as the rotor
D : Nr
For 3-phase induction motor, as load increases from no load towards the full load then the ___________
Options
A : power factor improves
B : power factor remains same
C : power factor varies linearly
D : power factor increases till 40% load and then decreases
If an emf at slip frequency is injected at an angle ? with existing rotor induced emf, then the ___________
Options
A : power factor only improves
B : speed changes
C : power factor improves and speed changes
D : power factor worsens and speed changes
If a 3-phase induction motor is fed from the rotor short circuiting the stator terminals, frequency of the current flowing in the short-circuited stator is?
Options
A : slip frequency
B : supply frequency
C : zero
D : frequency corresponding to the rotor speed
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