Final Review Motors Transformers

Front

What are designed to open the circuit when the current becomes 115% to 125% of the motor nameplate full-load current?

Back

Overloads

Front

In a three-phase motor, the speed of rotation of the magnetic field is called the _____ speed.

Back

Synchronous

Front

Which of the following is NOT a type of three-phase motor?
the squirrel-cage induction motor,
the wound-rotor induction motor,
the synchronous motor,
the rotating magnetic motor

Back

the rotating magnetic motor

Front

Which of the following is a factor in the easiest way to control the speed of a 3 phase motor?
Change the number of inverse rotations,
Change the number of magnetic rotations,
Change the frequency of the applied voltage,
Change the voltage

Back

Change the frequency of the applied voltage

Front

Some motors are constructed so that they will operate on either of two voltages. When they are connected to operate on the higher of the two voltages, the phase windings are connected in _____?

Back

Series

Front

Some motors are constructed so that they will operate on either of two voltages. When they are connected to operate on the lower of the two voltages, the phase windings are connected in _____?

Back

Parallel

Front

Three lines supply power to a three-phase motor. If one of these lines should open, the motor will be connected to single-phase power. This condition is known as _____?

Back

single-phasing

Front

To reverse the direction of rotation of a three-phase motor, reverse _____

Back

any two leads

Front

When a squirrel-cage motor is first started, the value of the current draw is _____

Back

several times the running current

Front

In a three-phase motor, what is the term used to describe the difference between synchronous speed and rotor speed?

Back

Slip