How Select Capacitor for Single Phase (230 Volt) Motor?

Hello Nishant

You are asking nearly the impossible, because of the large number of unknown variables.

At least you have the motor there, in front of you, but we can see nothing.

Advise what the motor used to run, or what you intend it to run.

Advise regarding the motor:

1. Size:
2. Diameter
3. Length
4. Shaft Diameter
5. Voltage

That would narrow some variables, but still make a guess by remote control.

The best and easiest thing to do, is to take it to a local electrician, who has probably seen such an item, and from his lengthy experience, should be able to help you.

That's about the best which may presently be done for you.

Kind Regards....

Hello Sparktation

I'll give you a good answer for that one, finding someone that has seen a similar motor is the only thing I can see short of a crystal ball. That or find the first start capacitor you have lying around that has the correct voltage rating plug it in and see if the motor starts or fries, if it starts call it good it will live for a little while.

There are some tricks using AC technique in measurements.

But it require really good Electrician, better Technician or Engineer with El-machinery practice.

Basically motor capacitors perform two functions. The first function is to start the motor and the second function is to run the motor. Some motors only require a run capacitor others require both a start and a run capacitor.

You'll have to tell us the wattage or horsepower rating of the motor for us to better answer your question. Any other information regarding the motor's former use would be helpful such as ;was it used in a fan, was it used to drive a compressor, etc.?

In these two instances a fan only needs a run capacitor because the starting torque requirements are low whereas a compressor motor usually starts against a load and needs a start capacitor to increase the starting torque.

I've had success with these dual use capacitors; www.plumbsupply.com/Images/FetchDocument.PDF

Hello again Nishant

Try a starting capacitor of around 30μF (microfarads) if it is ¹/₃ HP.

If the motor is ¹/₂ HP try a capacitor of 40μF (microfarads).

These should suit a motor running at 1430RPM or near that speed.

Please note these are approximate values, as there are variables unknown at present.

Advise your progress, or lack of same, thank you.

Kind Regards....

Hello Sparkstation
I still think your original idea is the best in the situation. This of course assumes there is motor shop someplace in his vicinity.

Most of the time in less the motor excessively large, I will set it on the counter at the motor shop, this avoids any confusion or me miss reading my own chicken scratch. And most of the time they know what the motor is without even looking at the tag.

It would be great if the original poster could provide some more information, possibly there's nothing on the motor at all. If it is a start capacitor as he first stated, and if the capacitor covers still intact those dimensions would be useful, or is the capacitors remote mount any thing would help.

Thank You for reply

pls describe the detail selection procedure of capacitor with respect to motor specification if any one know then it will be great help for us.