For the same H.P. rating and full load speed, following motor has poor starting torque_____________?

Hopkinson’s test on D.C. machines is conducted at_______________?

A. no-load
B. part load
C. full-load
D. overload

The hysteresis loss in a D.C. machine least depends on____________?

A. Frequency of magnetic reversals
B. Maximum value of flux density
C. Volume and grade of iron
D. Rate of flow of ventilating air

Which of the following motors is most suitable for signalling devices and many kinds of timers ?

A. D.C. shunt motor
B. D.C. series motor
C. Induction motor
D. Reluctance motor

Usually wide and sensitive speed control is desired in case of____________?

A. centrifugal pumps
B. elevators
C. steel rolling mills
D. colliery winders

If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking?

A. regenerative
B. plugging
C. dynamic braking
D. none of the above
E. any of the above

Starters are used with D.C. motors because______________?

A. these motors have high starting torque
B. these motors are not self-starting
C. back e.m.f. of these motors is zero initially
D. to restrict armature current as there is no back e.m.f. while starting