Single Phase Motor Obj.1 Flashcards
(28 cards)
What are the four types of Split Phase Induction Motors
- Resistance Start
- Capacitor Start
- Capacitor Run
- Dual Capacitor Motor
T or F
Single phase motors more efficient than three-phase motors of comparable horsepower. T or F?
False
What are the main components of the Resistance Split-Phase Motor?
Stator
Rotor
Frame
Centrifugal Switch
What is the main purpose of a Capacitor Run Split Phase Induction Motor?
Quiet and smooth operation
What is the main purpose of a Capacitor Start Split Phase Induction Motor?
To increase the starting torque
What are the common uses for a Shaded Pile Induction Motor?
Small home appliances such as hood fans, bath fans, and hot air blowers
What is another name for the main winding?
Run winding
What is another name for the Auxiliary Winding?
Start winding
What are the physical properties of the Main Winding?
Large conductors with many turns located at the bottom of the stator slots
What are the physical properties of the Start Winding?
Smaller conductors with fewer turns than the main winding, located at the top of the stator slots
Does the Main (run) Winding have ↓XL or ↑XL and ↓R or ↑R
Low resistance and high XL
Does the Start (aux) Winding have ↓XL or ↑XL and ↓R or ↑R
High resistance and low XL
What type of Rotor is used in a Split Phase Motor?
Squirrel Cage with a laminated steel core
At what percent of rated speed does the Centrifugal Switch open?
75%
What are two other methods of disconnecting the Start Winding?
Current Sensitive Relay and Electronic Switching
How is the Centrifugal Switch connected into the Start Winding?
In series
What is the phase displacement between the Start and the Main Winding current in the Resistance Split-Phase Motor?
20° - 30°
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?
Two-phase rotating magnetic field of 90 displacement
What type of magnetic field does the Run Winding produce on its own?
A pulsating magnetic field
Not like the the rotating magnetic field required to start the rotor.
Describe what happens during Cross Field Theory.
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.
What would happen if the Start Winding was left in the cct for to long?
The heat created will burn out the winding.
What is the standard Hp rating of a Split Phase Motor?
1/20 to 3/4.
The most common is 1/4
Would a wider phase angle produce a higher or lower starting Torque?
High
What is the starting torque rating of a Resistance Split Phase Motor?
125% - 150% or rated running torque
