Deck 4: Single-Phase Induction Motors

Question 1

Single-phase motors require ____ windings to operate.

A)main
B)auxiliary
C)terminal
D)three-phase

Answer 1

B

Question 2

____________________ capacitors are usually large microfarad AC electrolytic, and are designed to be in the energized circuit for only a short period of time.

Answer 2

Start

Question 3

The ____________________ switch assembly of the single-phase induction motor is designed to open the auxiliary start winding circuit once the rotor has reached a pre-determined speed.

Answer 3

centrifugal

Question 4

The standard direction of rotation for single-phase motors is counter-clockwise from the front of the motor, the end opposite the drive.

Question 5

What are at least two disadvantages to using single-phase motors?

Question 6

All motor applications require ____________________-phase motors in residential buildings.

Question 7

As the rotor reaches approximately ____% of synchronous speed, the auxiliary start winding is no longer necessary.

A)25
B)50
C)75
D)95

Question 8

The difference in ____ values causes the current in the auxiliary start winding to slightly lead the current in the run winding.

A)conductance
B)conductor
C)magnetic
D)inductance

Question 9

Single-phase induction motors are less complicated than three-phase motors.

Question 10

The ____ voltage found on motors is a terminal voltage, meaning that this is the voltage that should exist at the motor terminals after experiencing the feeder and branch circuit voltage drops of the electrical system.

A)NEMA
B)IEC
C)nameplate
D)de-energized

Question 11

The main winding is also called the ____ winding.

A)run
B)terminal
C)auxiliary
D)stop

Question 12

Single-phase induction motors are typically fractional horsepower; less than 1 HP.

Question 13

____ capacitors do not depend on a chemical reaction to achieve their capacitance, so they can be across the AC power supply line indefinitely.

A)Run
B)Start
C)Split-phase
D)Terminal

Question 14

____________________ capacitors are usually small microfarad paper and foil type, and are designed to be in the energized circuit for extended periods of time.

Question 15

The ____ motor has no centrifugal switch assembly, auxiliary start winding contact, or start capacitor.

A)capacitor-start
B)capacitor-run
C)capacitor-start, capacitor-run
D)split-phase

Question 16

The ____ motor is suitable only for loads with low locked rotor torque, such as fans and circulation pumps.

A)capacitor-start
B)capacitor-run
C)capacitor-start, capacitor-run
D)split-phase

Question 17

Large commercial and industrial building applications most often will use ____________________-phase motors.

Question 18

The ____ of rotation for single-phase motors is determined by the minute time differences between when the main run winding and the auxiliary start winding build a strong magnetic pole field, and the magnetic pole polarity differences between them.

A)direction
B)magnetism
C)strength
D)torque

Question 19

The operating characteristics of ____ motors make them suitable for applications like conveyors and compressors because of their high locked-rotor starting torque to get a load moving.

A)capacitor-start
B)capacitor-run
C)capacitor-start, capacitor-run
D)split-phase

Question 20

The ____ motor has a start capacitor in series with the auxiliary winding like the capacitor-start motor for improved high locked-rotor starting torque.

A)capacitor-start
B)capacitor-run
C)capacitor-start, capacitor run
D)split-phase