Single Phase Motor Obj.1

Question 1

What are the four types of Split Phase Induction Motors

Answer 1

1. Resistance Start
2. Capacitor Start
3. Capacitor Run
4. Dual Capacitor Motor

Question 2

T or F
Single phase motors more efficient than three-phase motors of comparable horsepower. T or F?

Answer 2

False

Question 3

What are the main components of the Resistance Split-Phase Motor?

Answer 3

Stator
Rotor
Frame
Centrifugal Switch

Question 4

What is the main purpose of a Capacitor Run Split Phase Induction Motor?

Answer 4

Quiet and smooth operation

Question 5

What is the main purpose of a Capacitor Start Split Phase Induction Motor?

Answer 5

To increase the starting torque

Question 6

What are the common uses for a Shaded Pile Induction Motor?

Answer 6

Small home appliances such as hood fans, bath fans, and hot air blowers

Question 7

What is another name for the main winding?

Answer 7

Run winding

Question 8

What is another name for the Auxiliary Winding?

Answer 8

Start winding

Question 9

What are the physical properties of the Main Winding?

Answer 9

Large conductors with many turns located at the bottom of the stator slots

Question 10

What are the physical properties of the Start Winding?

Answer 10

Smaller conductors with fewer turns than the main winding, located at the top of the stator slots

Question 11

Does the Main (run) Winding have ↓XL or ↑XL and ↓R or ↑R

Answer 11

Low resistance and high XL

Question 12

Does the Start (aux) Winding have ↓XL or ↑XL and ↓R or ↑R

Answer 12

High resistance and low XL

Question 13

What type of Rotor is used in a Split Phase Motor?

Answer 13

Squirrel Cage with a laminated steel core

Question 14

At what percent of rated speed does the Centrifugal Switch open?

Answer 14

75%

Question 15

What are two other methods of disconnecting the Start Winding?

Answer 15

Current Sensitive Relay and Electronic Switching

Question 16

How is the Centrifugal Switch connected into the Start Winding?

Answer 16

In series

Question 17

What is the phase displacement between the Start and the Main Winding current in the Resistance Split-Phase Motor?

Answer 17

20° - 30°

Question 18

While a Resistance Split Phase Motor is running (after the centrifugal switch has opened) the cross field effect will result in the motor simulating what type of magnetic field?

Answer 18

Two-phase rotating magnetic field of 90 displacement

Question 19

What type of magnetic field does the Run Winding produce on its own?

Answer 19

A pulsating magnetic field
Not like the the rotating magnetic field required to start the rotor.

Question 20

Describe what happens during Cross Field Theory.

Answer 20

The Start Winding is kept in the cct (75% or rated speed) until the rotor develops enough magnetic field intensity to produce cross field theory. This attraction develops the running torque as the Rotor is highly inductive.

Question 21

What would happen if the Start Winding was left in the cct for to long?

Answer 21

The heat created will burn out the winding.

Question 22

What is the standard Hp rating of a Split Phase Motor?

Answer 22

1/20 to 3/4.
The most common is 1/4

Question 23

Would a wider phase angle produce a higher or lower starting Torque?

Answer 23

High

Question 24

What is the starting torque rating of a Resistance Split Phase Motor?

Answer 24

125% - 150% or rated running torque

Question 25

Does a Resistance Split Phase Motor have high or low starting current?

Answer 25

High starting current
and a low starting torque

Question 26

What is the biggest downfall to using a Resistance Split Phase Motor?

Answer 26

High noise factor due to vibrations from the pulsating power

Question 27

Is a Resistance Split Phase Motor reversible or reversing?

Answer 27

Reversible
The rotation can be changed while at standstill

Question 28

What are the common uses for a Resistance Split Phase Motor?

Answer 28

Forced air furnace fan
Washing machines
Small drill press
Fans
Sump pumps