Test 1

When a load is applied to a 3-phase squirrel cage-motor induction motor, the rotor speed will

decrease slightly

Direct current permanent magnet servo motors are used in cranes to start heavy loads

false

The locked-rotor starting current of an induction motor is several times less than the full-load current.

false

direct current motors can normally operate directly from the power supplied by the electric utility system.

false

the speed of a squirrel-cage motor can be varied by varying the supply?

frequency

A wound - rotor induction motor is normally started with

full external rotor existence

The shunt-type DC motor is know to have

good speed regulation

The series-type DC motor has

high starting torqe

A polyphase synchronous motor is frequently used to

improve power factors

As the load on an induction increases the power factor will

increase

A _________ is an example of a constant horsepower load

lathe

The commutator in a DC motor reverses armature coil current flow to produce continuous armature rotation.

true

The speed of a DC shunt motor is inversely proportional to the field current.

true

the direction of rotation for a 3-phase AC motor can be changed by exchanging L1 and L2 of the supply voltage.

true

the speed of a 3-phase synchronous motor is the same as that of rotating magnetic field

true

A series-type DC motor uses filed coils?

with low resistance made up of a few turns of large diameter wire

DC shunt motor should never be operated

with the field circuit open

a DC series motor runs fast with a light load

True

On a 3-phase motor, the stator windings are arranged to create

a rotating magnetic field

the __________ motor has the highest starting torque of all single phase motors

capacitor start/ capacitor run

the _____________________ motor has the highest starting torque of all the single phase motors

capacitor start/ capacitor run

The purpose of a commutator on a DC motor is

To maintain the proper direction of current flow in the armature conductors.

A good capacitor will hold will hold a charge even when the power is removed.

True

A split-phase motor relies on the start winding to create a phase shift.

True

Overheated bearings may cause motor noise

True

The synchronous speed of a 2-pole, 60hz AC motor is

3600 RPM

Which of the following is not a requirement for motor action?

A source of mechanical energy

TWO basic categories of motors are

AC and DC

A variable AC motor drive is able to operate the motor

ALL the above, (above, at and below base speed)

Shunt field coil wingdings of DC mtors

All the above

The Voltage induced into the armature of a DC motor is known as the

CEMF

An electric motor uses ______________ to operate

Electric Current, Magnetism

A current-carrying conductor, placed in and right angles to a magnetic field, tends to move parallel to the field

False

Single phase operation of a 3-phase motor will reduce the current in the two remaining phases.

False

Unlike 3-phase induction motors, single-phase types are self-starting.

False

Which of the following NEMA insulation classes has the highest safe maxiumum operating temp

NEMA H

If the field current of a shunt-type DC motor is held constant and the armature voltage is increased, as a result,

Speed of the motor will increase

Torque is best defined as

The turning force produced by a motor

Single-phasing refers to the operation of a 3-phase motor on two phases because one phase is lost.

True

the direction of rotation of a 3-phase induction motor is determined by

phase sequence

DC compound motors are used to operate loads that require

relatively constant speed under varying loads

The direction of rotation of a shunt wound DC motor is changed by

reversing the current flow through the armature reversing the current flow through the field

The synchronous speed of an induction motor refers to the speed of the

rotating magnetic field

The universal motor is constructed similar to that of a _________ type DC motor

series

A DC series motor

should never be operated without a LOAD

A squirrel-cage rotor consists of

single bars short circuited by end rings

The direction of rotation on a split-phase motor can be reversed by interchanging the connections to

the run winding, the start winding

One advantage DC type motors have over AC types is that

their speed can be easily varied

A three-phase synchronous motor can produce a leading power factor

true

Compared to a squirrel-cage motor equivalent horsepower, a wound rotor motor has a higher starting torque and lower starting current.

true