Capacitors
- Thread starter JdoubleU
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barbeer
Senior Member
- Location
- Pinellas County, FL
Here is half the story! http://64.226.146.90/Tutorials/Motor%20Starting%20Capacitors.htm
yucan2
Senior Member
- Location
- Just south of Chicago
Both items of concern are addressed here: in posts 2 & 4.
http://forum.allaboutcircuits.com/showthread.php?t=1223
http://forum.allaboutcircuits.com/showthread.php?t=1223
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
090428-2059 EST
In post #2 of the allaboutcircuits reference the majority of what was said is nonsense.
Most do not have a permanent magnet rotor. That would be used in a synchronous motor. Most are induction motors.
I won't go into a discussion of how single phase motors work, or multiphase phase motors.
Go find some better sources on the internet, or visit a good library.
The following is a good discussion, but it does not tell you how the motor works:
http://www.clrwtr.com/Single-Phase-Electric-Motors-Characteristics-Applications.htm
At the moment I can not direct you to a good source. Most that I quickly looked at on the Internet are very inadequate or basically nonsense.
.
In post #2 of the allaboutcircuits reference the majority of what was said is nonsense.
Most do not have a permanent magnet rotor. That would be used in a synchronous motor. Most are induction motors.
I won't go into a discussion of how single phase motors work, or multiphase phase motors.
Go find some better sources on the internet, or visit a good library.
The following is a good discussion, but it does not tell you how the motor works:
http://www.clrwtr.com/Single-Phase-Electric-Motors-Characteristics-Applications.htm
At the moment I can not direct you to a good source. Most that I quickly looked at on the Internet are very inadequate or basically nonsense.
.
beanland
Senior Member
- Location
- Vancouver, WA
2-phase motor
2-phase motor
A single phase motor will not start unless helped.
It is helped by making it a 2-phase motor.
That is accomplished by adding a second winding in the motor.
That starting winding is rotated in the stator at a magnetic angle to the main winding.
The current in this starting winding is caused to be out of phase with the main winding by putting the capacitor in series with the starting winding circuit.
The combination of the magnetic field from the main winding and the offset magnetic field in the starting winding creates starting torque to make the motor function.
In a capacitor start motor, the capacitor and start winding are used just to get the motor turning.
In a capacitor-start, capacitor-run motor, a large capacitor us used to start the motor and then a smaller one is used when the motor is running. This creates a pseudo-two-phase motor.
A CSCR motor has more starting torque and higher efficiency than many options and is common in small compressor applications where high starting torque is needed.
2-phase motor
A single phase motor will not start unless helped.
It is helped by making it a 2-phase motor.
That is accomplished by adding a second winding in the motor.
That starting winding is rotated in the stator at a magnetic angle to the main winding.
The current in this starting winding is caused to be out of phase with the main winding by putting the capacitor in series with the starting winding circuit.
The combination of the magnetic field from the main winding and the offset magnetic field in the starting winding creates starting torque to make the motor function.
In a capacitor start motor, the capacitor and start winding are used just to get the motor turning.
In a capacitor-start, capacitor-run motor, a large capacitor us used to start the motor and then a smaller one is used when the motor is running. This creates a pseudo-two-phase motor.
A CSCR motor has more starting torque and higher efficiency than many options and is common in small compressor applications where high starting torque is needed.
Skyline Electric
Member
Excellent explanation! I always wondered about that. Thanks!
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