Motor/capacitor sizing

[westburywheeler]

Hi all first post so fingers crossed, We have a single phase motor on a m/c that requires a new capacitor (motor buzzes and cant decide which way to start unless you help it) there is no information on the capacitor other than 'balenced with half key'. The motor is rated at .75kw what size capacitor do we need ?
Regards, Mark.

 

[waross]

Duh.... Frequency and voltage may help just a little.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[westburywheeler]

Sorry 240v 50hz thought single phase would cover it. Run amps 7.2

 

[waross]

Depends on the connection of the starting winding.
If the starting winding uses 240 Volts try 250 MFD to 300 MFD.
Some dual voltage (115:230V) motors use 115 Volts on the start winding. In that case try 500 MFD to 600 MFD.
The size is not critical. Years ago I had an issue with breakaway torque. I doubled the starting capacitors on two motors. That gave me the extra starting torque that I needed. The motors have been running for 10 or 15 years with no issues.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[westburywheeler]

Thanks will order one up.
Regards,
Mark.

 

[jraef]

Often though, that symptom is indicative of the Start Switch being stuck open, not the cap being bad. Check that first if you have not already bought the cap.

Been there, done that, got the T-shirt and the hat.

"Will work for (the memory of) salami"