Hi,
normally a single phase AC motor looks like this:
Code:
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o------------o--------------------o------o
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| centrifugal switch |
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| _--o---------------o-||-o
o o ||
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C| C| mains AC
run winding C| C| start winding
C| C|
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o o
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o--------o---o---------------------------o
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inside motor | outside motor
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created by Andy´s ASCII-Circuit v1.24.140803 Beta [url]www.tech-chat.de[/url]
How to identify the windings:
You can measure 3 different resistance values of the windings:
- high: start winding ---- run winding
- middle: common ---- start winding
- low: common ---- run winding
The capacitor is used to create a phase shift between run winding and start winding what causes the motor to start always in the same direction. If no capacitor is used the motor can be started by spinning it in any direction.
The value of the capacitor is ~7µF/kW motor power.
If the motor has not been used for 10 years have a look at the bearings. They might be dirty and/or rusty and should be changed.
Also have a look at the centrifugal switch. If it's not working correctly the start winding will not be switched off and might be overheated after a while.
When starting a single phase AC motor has low torque, so it might be usefull to start it with no or low mechanical load.
hth
regards
joachim