an ordinary static capacitor bank

an over-excited synchronous motor driving mechanical load

an over excited synchronous motor running without mechanical load

none of the above

45

90

between 45 and 90

below 60

current to the field winding

supply phase sequence

polarity of rotor poles

none of the above

it can be over excited

it has two sets of rotor poles

both its rotor and stator are excited

it needs twice the normal exciting current

stabilize rotor motion

suppress rotor oscillations

develop necessary starting torque

both 1) suppress rotor oscillations and 2) develop necessary starting torque