302. Which of the following methods gives the greatest braking torque?
A. Regenerative braking
B. Plugging
C. Rheostatic braking
D. None of the above
303. A brake test on D.C. motors restricted to
A. small horse power motors
B. variable speed motors
C. high speed motors
D. open frame type motors.
304. In case of D.C. machines, mechanical losses are primary function of
A. current
B. voltage
C. speed
D. none of above
305. Iron losses in a D.C. machine are independent of variations in
A. speed
B. load
C. voltage
D. speed and voltage
306. In D.C. generator, on no load
A. magnetic neutral axis moves from geometrical neutral axis in the opposite direction of rotation
B. magnetic neutral axis coincides with geometrical neutral axis
C. magnetic neutral axis moves from geometrical neutral axis in the direction of rotation
D. none of the above
307. If B is the flux density, / the length of conductor and v the velocity of conductor, then induced e.m.f. is given by
A. B/v
B. B/v2
C. B/2v
D. Bpv2
308. For generating large currents on D.C. generators which winding is generally preferred?
A. Progressive wave winding
B. Lap winding
C. Retrogressive wave winding
D. Current depends on design
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