Synchronous motors

high excitation only

low excitation only

both high and low excitation

none of the above

When supply voltage fluctuates

When load varies

When power factor is unity

Motor is under loaded

Windage loss

Bearing friction loss

Copper loss

Core loss

d.c. shunt machines

d.c. series machines

d.c. compound machines

any of the above

lagging power factor only

leading power factor only

unity power factor only

lagging, leading and unity power factors

mild steel

chrome steel

alnico

stainless steel

Phase to phase winding resistance

Stator winding to earthed frame

Rotor winding to earthed shaft

All of the above

Fluctuating loads

Variable speed loads

Low torque loads

Power factor corrections

changing the load

changing the supply voltage

changing frequency

using brakes

its power factor may be varied at will

its speed is independent of supply frequency

its speed may be controlled more easily

none of the above