ECN Forum Forums Technical Discussion Electrical Theory and Applications working of compressor motor

what are the modifications that we have to take to operate at 240 V, 50 Hz compressor motor which is designed for 115 V,60 Hz?

First you need a transformer to change the supply voltage to that of the motor. Then you need to change the suppy frequency to that of the motor. 60Hz devices will overheat and fail if used on 50Hz.

The easiest way to change frequency is with a Variable Frequency Drive (VFD), however these are not readily available for single phase motors.

Change the motor and sell the 115v one. Cheapest, easiest and safest option. Make sure the new motor has the same rpm, [ie same number of poles], and is the same type; that is to say you need a capacitor start/run motor NOT a split-phase type; and if you can get the same frame size it will fit in the same bolt-holes and pulley bore and use the original vee-belt.
- If it's an inline-drive: IMHO, forget it!
BTW a VFD & Transformer could cost you more than a brand new compresssor.

Alan

ps. Don't worry too much about 50 vs 60 hz in this situation; the compressor will just run a bit slower, eg 3000 rpm instead of 3600 rpm if it's a 2-pole.


[This message has been edited by Alan Belson (edited 09-18-2006).]