In air-condition system,compressor is a main component to pump the refrigerant circulation in system.It like our heart to pump a blood all around human system.If this part breakdown or have a problem,all system is paralyze.
Normally for single phase air-condition system,the common type of electric motor is running capacitor motor and used scroll type compressor.The famous brand now in market such as Copeland,Daikin,Toshiba,Mitsubishi and others brands.
I want explain about single phase motor for air-condition or refrigerator compressor basic concept and how to check their winding condition and connection.
Wiring for single phase motor
1) Run capacitor
2) Start and run capacitor
How to check motor compressor connection?
For single phase compressor,normally it have 3 connection for winding.It is common ( C ) ,Starting winding ( S ) and Running winding ( R ).We can determine this 3 connection using a multimeter.We measure the ohm value of 3 connection to confirm the winding.
- Measure from all of 3 connection and write down the ohm value,example :-
point 1 to point 2 = 3 ohm
point 2 to point 3 = 8 ohm
point 3 to point 1 = 6 ohm
- Draw the triangle line and insert the ohm value,example :-
- From this triangle,we can determine the connection of motor winding either common ( C ) , Starting ( S ) or Running ( R ).The formula is simple.
1) Common connection ( C ),ohm value is a highest.From this example it is 8 ohm.
2) Starting connection ( S ),ohm value is a second higher,it is 6 ohm
3) Running connection ( R ),ohm value is a lowest,it is 3 ohm.
How to check single phase motor compressor winding condition?
The methods to check motor condition is easy and simple.We must check the winding to winding short and partially shorted winding.
1) winding to winding short
- Use a multimeter and select to ohm.Check all of 3 connection to earthing or compressor body( scratch out the paint from compressor body to get a continuity) .Write down the value from 3 of connection.
- For the good winding,the ohm value must infinity.It mean no connection between winding and earthing.
- For shorted winding,the ohm value is 0 ( zero ).it mean winding and earthing have a connection / shorted.
2) partially shorted winding
- Measure the ohm value for connection Common to Running and Common to Starting.
- Record the value, example :-
C to R = 0.5 ohm
C to S = 3 ohm
- The formula to determine a winding condition is good,the resistance of starting winding is equal 3 to 6 times of running winding
3 ohm / 0.5 ohm = 6 ( winding for this compressor is good )
- We must remember this formula : “The good winding ohm value must in range between equal 3 to 6 times.If value out off this range,we can assume the winding is shorted and defected.”