The torque of an induction motor is___________?
(A) directly proportional to slip
(B) inversely proportional to slip
(C) proportional to the square of the slip
(D) none of the above
The frame of an induction motor is usually made of____________?
(A) silicon steel
(B) cast iron
(C) aluminium
(D) bronze
A D.C. generator works on the principle of____________?
(A) Lenz’s law
(B) Ohm’s law
(C) Faraday’s law of electromagnetic induction
(D) none of the above
A series generator can self-excite:______________?
(A) only if the load current is zero
(B) only if the load current is not zero
(C) irrespective of the value of load current
(D) none of the above
The open circuit voltage of a compound generator is 250 V. At full load the terminal voltage____________?
(A) will be less than 250 V
(B) will always be 250 V
(C) may be greater or less than 250 V
(D) none of the above
The terminal voltage of a series generator is 150 V when the load current is 5 A. If the load current is increased to 10 A, the terminal voltage will be____________?
(A) 150 V
(B) less than 150 V
(C) greater than 150 V
(D) none of the above
A shunt generator can self-excite:_________________?
(A) only if the resistance of the field circuit is less than critical value
(B) only if the resistance of the field circuit is greater than critical value
(C) irrespective of the value of the resistance in the field circuit
(D) none
With a D.C. generator which of the following regulation is preferred ?
(A) 100% regulation
(B) infinite regulation
(C) 50% regulation
(D) 1% regulation
Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be_____________________?
(A) 270 V
(B) 267.5 V
(C) 265 V
(D) 257.4 V
In squirrel cage induction motors, the rotor slots are usually given slight skew in order to__________?
(A) reduce windage losses
(B) reduce eddy currents
(C) reduce accumulation of dirt and dust
(D) reduce magnetic hum