In a D.C. generator, the iron losses mainly take place in___________/
(A) yoke
(B) commutator
(C) armature conductors
(D) armature rotor
D.C. generators are normally designed for maximum efficiency around_____________?
(A) full-load
(B) rated r.p.m.
(C) rated voltage
(D) all of the above
The condition for maximum efficiency for a D.C. generator is______________?
(A) eddy current losses = stray losses
(B) hysteresis losses = eddy current losses
(C) copper losses = 0
(D) variable losses = constant losses
The total losses in a well designed D.C. generator of 10 kW will be nearly______________?
(A) 100 W
(B) 500 W
(C) 1000 W
(D) 1500 W
Which of the following losses are significantly reduced by laminating the core of a D.C. generator ?
(A) Hysteresis losses
(B) Eddy current losses
(C) Copper losses
(D) Windage losses
Which of the following loss in a D.C. generator is dissipated in the form of heat?
(A) Mechanical loss
(B) Core loss
(C) Copper loss
(D) All of the above
Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator ?
(A) Providing laminations in armature core
(B) Providing laminations in stator
(C) Using non-magnetic material for frame
(D) Using material of low hysteresis co-efficient for armature core material
D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select this______________?
(A) series motor
(B) shunt motor
(C) compound motor
(D) any of the above
D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the________________?
(A) series motor
(B) shunt motor
(C) compound motor
(D) any of the above
If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens____________?
(A) this will make armature to take heavy current, possibly burning it
(B) this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
(C) nothing will happen to motor
(D) motor will come to stop