Chg Capacitor 115v to 230v

[sturdy]

Hi,

I have an old 2HP dual voltage compressor motor that I want to run on 230 instead of 115. The starting capacitor is 594 mfd 110vac. If I rewire for 230v, what should be the value of the capacitor? tia

Sturdy

 

[busbar]

Very likely the same.

 

[volvibeguy]

sturdy,
If the motor came factory with the mentioned capacitor and dual voltage taps, then most likely the only difference you will encounter is the power tap connection of the motor leads.
Hope this helps.
JB

 

[jbartos]

Suggestion: Please, describe that capacitor. Is it a simple two terminal capacitor or are there more terminals on that capacitor?

 

[SteveKW]

If it is a DUAL voltage motor ... regardless of how you connect it ... high or low voltage ... the start winding ALWAYS sees low voltage!

 

[sturdy]

My thanks to all...
Factory motor with dual voltage taps, two terminals on the cap. After a little thought, this makes sense. Guess I'll stick to something simple, like computers.

Sturdy

 

[jbartos]

Suggestion: Certainly it makes sense, even if one considers different start at 115V with respect to 230V. The start at 230V is probably more powerful and faster than at 115V.

 

[SteveKW]

"The start at 230V is probably more powerful and faster than at 115V."

I have seen this before and disagree!

Putting aside the voltage drop from the wiring to the motor on 110 volts ...

A motor connected 110 volts has ALL of its windings ACROSS the line as opposed to having the motor 220 volts and the start windings in SERIES with one of the run windings.


Would that not limit the current to the start windings and therefore dampen the starting torque???


Am I wrong?
Will the voltage drop at 110 volts decide it?

 

[jbartos]

Suggestion to SteveKW (Electrical) Jul 9, 2003 marked ///\\If it is a DUAL voltage motor ... regardless of how you connect it ... high or low voltage ... the start winding ALWAYS sees low voltage!
///Assuming that this is correct, then\\A motor connected 110 volts has ALL of its windings ACROSS the line as opposed to having the motor 220 volts and the start windings in SERIES with one of the run windings.
///This means that the 110V start winding in series with one of the run winding has 110V and the run winding has 110V. Then, after the start is performed, the start winding will be turned off and the run windind 110V will be connected to 230V or will not?\\\

 

[busbar]

See first illustration in

http://www.cybernetic.com.au/Bowling/diagrams/Ssbe_C90DV.pdf

In some cases, the run winding may be used as a short-duty autotransformer.

 

[SteveKW]

It sure sounds like I am contradicting myself!

Ignore my previous posts...

Using Busbars last link (

http://www.cybernetic.com.au/Bowling/diagrams/Ssbe_C90DV.pdf

) showing the single phase motor connected 220 volts and the START windings attached BETWEEN the two run windings...


Would not the series/parallel circuit shown there NOT have an EXACT voltage of 110 at the center point (labeled #4 between lead numbers 2 & 3) ?

 

[jbartos]

Suggestion: It appears the run winding in parallel with the start winding at 220V would have a different total impedance than the run winding connected in parallel with the start winding at 110V, assuming that Run Windings at 220V connection are identically the same, i.e. winding between 1 and 2 is equal to winding between 3 and 4.