Unit 32 test

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

any two leads

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

several times the running current

The motor wiring diagram below indicates the motor is wired for ____________________ voltage.

wye high voltage

The synchronous motor is an induction motor

False

The squirrel-cage rotor code letters indicate the shape (type) of rotor bars. Different types of bars have a large effect on the _____ of a motor.

starting torque

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

synchronous

A synchronous motor operated with no load and used for power factor correction is sometimes called a _____.

synchronous condenser

The set of squirrel-cage bars on the rotor of a synchronous motor is used to start the motor and is known as the _____.

amortisseur winding

The squirrel-cage rotor is constructed of _____ and end _____ embedded in steel laminations.

bars; rings

The wound-rotor induction motor is popular in industry because it has _____ starting torque and _____ starting current

high; low

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 windings are connected in _____.

parallel

If a piece of machinery needs a replacement motor and will be damaged if the new motor rotates the wrong way. The test equipment needed to test the rotation direction of the new motor is a _____.

phase rotation meter

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 windings are connected in _____.

series

Selsyn motors operate on _____ voltage

single phase

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 _____.

single phase

The motor wiring diagram below indicates the motor is wired for ____________________ voltage.

Wye low voltage

The torque of a squirrel-cage induction motor will be maximum when the phase angle between the stator and rotor fields is _____.

0%

A motor is operating at 3450 RPM and is producing a torque of 32 lb-in. What is the output horsepower of the motor?

1.75

A squirrel-cage rotor induction motor has a synchronous speed of 3600 RPM and an actual rotor speed of 3450 RPM. What is the percent slip?

4.17%

For most squirrel-cage induction motors the typical percent slip is about _____ percent

two to five