Unite 17 Types Of Electrical Motor

Question 1

Motors have two different current ratings, the full-load or rated amps (FLA or RLA) and the ____________.

Answer 1

locked-rotor amps

Question 2

The difference between the motor’s calculated and actual speed is called _______.

Answer 2

motor slip

Question 3

The _________ is used with some motors to open the start windings after the motor has started.

Answer 3

Start capacitor

Question 4

The amount by which the current leads or lags the voltage is called phase angle.

True or false

Answer 4

True

Question 5

A start capacitor is wired into the circuit to provide the most efficient phase angle between the current and voltage when the motor is running.

true or false

Answer 5

False

Question 6

When enough back EMF has built up, called _______ voltage, the contacts between terminals 1 and 2 of a potential relay will open.

Answer 6

Pick up

Question 7

A positive temperature coefficient resistor (PTCR) increases ______

Answer 7

its resistance as its temperature increase

Question 8

The resistance between the terminals of a three-phase compressor motor __________.

Answer 8

Is the same

Question 9

The two basic types of converters are the phase-controlled rectifier and the diode bridge rectifier.

True or false

Answer 9

True

Question 10

A _________ receives a fixed DC voltage from the converter and then pulses the voltage to the motor.

Answer 10

Pulse with modulators

Question 11

When an alternating current is applied to
the running windings of a split-phase electric motor, an
alternating current. __________________________

Answer 11

with reverse polarity is induced in the rotor

Question 12

A two-pole split-phase motor operates at a speed

just under

Answer 12

3600 rpm

Question 13

The start windings has

Answer 13

more turns than the run winding

Question 14

A four-pole split-phase motor runs __________

Answer 14

Slower than

Question 15

When a typical split-phase motor reaches approximately 75% of its operating speed, the start winding circuit is removed from the circuit by a

Answer 15

Centrifugal switch

Question 16

A three phase power supply can be found in most

Answer 16

Factories

Question 17

The electronic relay is used with some electric

motors to open

Answer 17

the circuit to the start windings after

motor has started

Question 18

The amount by which the current leads or lags

the voltage in alternating current circuit is known as the

Answer 18

Phase angle

Question 19

In an alternating current circuit in which there is

the voltage capacitor, the current __________ the voltage

Answer 19

Leads

Question 20

Capacitors wired in series with the start windings

provide

Answer 20

A greater starting torque

Question 21

The shaded-pole motor has

Answer 21

little starting torque

Question 22

Three-phase motors have

Answer 22

no start windings or start capacitors.

Question 23

The tem “slip” is used to indicate

Answer 23

the difference between the full operational
rpm rating of the motor and the actual speed
under a load

Question 24

The hermetic motor must run in a

Answer 24

refrigerant vapor atmospheres

Question 25

The start winding circuit in a hermetic motor is
interrupted by a potential relay or a current relay
because______________ mechanical switch

Answer 25

of the electric are produced by a mechanical switch

Question 26

The positive-temperature-coefficient start device is

a type of

Answer 26

Thermistor

Question 27

A two-speed compressor motor may operate as a

Answer 27

two- or four-pole motor

Question 28

Most small hermetic motors are cooled by

Answer 28

refrigerant gas

Question 29

(PTCR) means

Answer 29

Positive temperature coefficient resistor

Question 30

What device may be wired into the running circuit of a motor to improve the running efficiency?

Answer 30

Run capacitors

Question 31

The two types or relays used to start hermetic compressors are

Answer 31

Potential relays, and current relays.

Question 32

Question

Answer 32

An