17

Question 1

Converts AC power to DC by use of phase-controlled rectifier or diode bridge
rectifier.

Answer 1

Dc converter

Question 2

Electronic device in a motor circuit that is used to control motor speed for variable
speed motors.

Answer 2

Pulse Width Modulator

Question 3

Single phase motor with a start and run winding that has a capacitor in series with
the start winding which remains in the circuit until the motor gets up to 75% of the motor’s rated speed.

Answer 3

Capacitor start motor

Question 4

Assists in starting the motor using BEMF to cut out the start capacitor.

Answer 4

Potential relay

Question 5

Used as a switch or as a device to amplify or increase an electrical signal.
Convert DC power to AC power.

Answer 5

Transistor

Question 6

When the contacts between terminals 1 & 2 in a potential relay will be opened by
BEMF.

Answer 6

Pick up voltage

Question 7

As temperature increases, resistance increases. Acts as an open circuit and stops
all current flow through a circuit.

Answer 7

PTC start device

Question 8

Switching or transistor section of the variable frequency drive that produces an
AC voltage at just the right frequency for motor speed control.

Answer 8

Inverter

Question 9

Induced voltage in the start winding that is used to open the switch in a potential
relay.

Answer 9

BEMF

Question 10

Similar to a split phase motor but does not have a start capacitor. Used for low
starting torque applications.

Answer 10

PSC motor

Question 11

Maximum EMF that the coil can tolerate continuously without overheating and
opening the circuit in a potential relay.

Answer 11

Continuous coil voltage

Question 12

Single phase motor that has a start capacitor in series with the start winding that is disconnected after start-up and run capacitor in parallel that stays in the circuit while running.

Answer 12

Capacitor start capacitor run motor

Question 13

Cycles per second of the electrical current that the power company supplies. Can
be either 50 or 60 Hz depending on geographical location.

Answer 13

Frequency

Question 14

The speed at which power devices in the VFD switch on and off.

Answer 14

Switch frequency or carrier frequency

Question 15

Used to control the capacity of small compressors. Can be considered as tow
motors in one housing.

Answer 15

Two speed compressor motor

Question 16

Solid state device used with some motors to open the start windings after the
motor has started.

Answer 16

Electronic relay

Question 17

The stator is the rotating part of an electrical motor. T/F

Answer 17

F

Question 18

Synchronous motors have slip. T/F

Answer 18

F

Question 19

If a three-phase fan rotates in the wrong direction, it will move only about half
as much air. T/F

Answer 19

T

Question 20

The heavier the load on an operating motor, the greater the amount of slip. T/F

Answer 20

T

Question 21

The centrifugal switch mounted on the shaft of a split-phase motor has a normally closed contact. T/F

Answer 21

T

Question 22

_If the switch or the coil in a potential relay have a reading of “OL” when checking resistance, the potential relay is good. T/F

Answer 22

F

Question 23

The microfarad rating of the run capacitor is lower than that of the start capacitor for any given motor. T/F

Answer 23

T

Question 24

A permanent-split capacitor motor has a run capacitor only. T/F

Answer 24

T

Question 25

The contacts in a potential type starting relay are normally open. T/F

Answer 25

F

Question 26

A capacitor-start capacitor-run motor that is wired with a potential relay will have the start winding energized when the relay's contacts are open. T/F

Answer 26

T

Question 27

Terminal S of a current relay is connected to the Start winding. T/F

Answer 27

T

Question 28

The contacts in a current type starting relay are normally closed. T/F

Answer 28

F

Question 29

Two speed compressor motors have more than three motor terminals to operate its two motors. T/F

Answer 29

F

Question 30

The difference between a split phase motor and a PSC motor is the split phase motor will have a run capacitor and the PSC motor will have a start capacitor. T/F

Answer 30

F

Question 31

The full wave rectifier moves the negative portion of the sine wave to the positive side of the sine wave thus converting AC voltage to pulsating DC voltage. T/F

Answer 31

T

Question 32

The Service Factor (SF) on a motor data plate is 1.25. How many amps can the motor draw above its full load amp rating of 5A, for a limited time, without damaging the motor?

Answer 32

6.25 A

Question 33

Motor A has a rating of 1800 pm, motor B has a rating of 1200 pm and motor C has a rating of 3600 rpm. Which motor has the most poles?

Answer 33

Motor B

Question 34

motor that has 4 poles and is powered by 60 Hz voltage has a no-load speed of how many rotations per minute?

Answer 34

1800 rpm

Question 35

What does it mean when a 3-phase motor is single phasing?

Answer 35

One of the phases dropped out

Question 36

Switch, filter, or rectification Transistor

Answer 36

Switch

Question 37

Switch, filter, or rectification Inverter

Answer 37

Switch

Question 38

Switch, filter, or rectification Silicone controlled rectifier

Answer 38

Rectification

Question 39

Switch, filter, or rectification Capacitor

Answer 39

Filter

Question 40

Switch, filter, or rectification Diode

Answer 40

Rectification

Question 41

Switch, filter, or rectification Choke

Answer 41

Filter

Question 42

Switch, filter, or rectification Pulse width modulation

Answer 42

Switch

Question 43

List the steps you would take to check out a 3-phase disconnect for the proper voltage.

Answer 43

check above the fuses, the line side voltage. Then check The load side going to the load.

Question 44

Name four devices that may be used to remove the start capacitor from the motor starting circuit.

Answer 44

Centrifugal switch, current relay, potential relay, electronic relay

Question 45

You are checking the switch in a potential relay. What terminals do you place your probes on?

Answer 45

1 and 2

Question 46

When voltage leads current

Answer 46

Inductive

Question 47

When current leads voltage

Answer 47

Capacitive

Question 48

What is the total capacitance going to the start winding circuit when the start capacitor is 110 uf and the run capacitor is 10 uf in diagram A?

Answer 48

120

Question 49

If Common to Run measures OL what is the expected resistance reading for Run to Start?

Answer 49

OL

Question 50

Common to Start measures OL. Common to Run measures OL. Run to Start measures 5 Q. What is wrong with the compressor?

Answer 50

Open internal overload

Question 51

When measuring the motor windings of an ECM motor, what is the expected resistance of all the windings?

Answer 51

All the same