Rotary Phase Converter

[chriskat]

I'm getting close to building a RPC and I am contemplating this motor:

http://www.surpluscenter.com/item.as...tname=electric

I have a potentially dumb question. If I feed this thing with 220 V and the motor is wired to run on 220 I will get 220V out on the third leg, won't I?

[J. R. Williams]

Chris
What you get out of the third leg depends on the number and value of capacitors used in the system. It will vary with the connected load.

Have fun

JRW

[wierdscience]

If you look around locally you can probibly find a good used motor for $5-10 in that size.Try scrapyards,motor shops and surplus dealers.

If you find a scrapyard,theye are usually the best since they don't like motors.My local yard sells me anything I want in the way of motors for $.02/lb,most times the three phase motors are good,just attached to obsolete equipment.

[sauer38h]

<font face="Verdana, Arial" size="2">Originally posted by chriskat:
If I feed this thing with 220 V and the motor is wired to run on 220 I will get 220V out on the third leg, won't I?</font>

More or less, yes.

[smootz]

My rpc acts exactly like a 3 phase utility feed does.

When checking voltage across any 2 lines you will read 220V.

However, when you check from line to ground, 2 of the lines will read 120V while the 3rd will read 240V.

This is normal and poses no problem. When wiring regular 3 phase supplied by the utility company you should put this "hotter" line on the middle buss of your box. Be careful when tapping into your system for 110V machine accessories such as lighting and coolant pumps to avoid this center "hot" leg or you will get smoke. Also, some magnetic contactors (even 220V 3 phase ones) require 110V for the coil. Don't ask me how I know!

[dr dave]

My rpc acts exactly like a 3 phase utility feed does.

When checking voltage across any 2 lines you will read 220V.

However, when you check from line to ground, 2 of the lines will read 120V while the 3rd will read 240V.

This is normal and poses no problem. When wiring regular 3 phase supplied by the utility company you should put this "hotter" line on the middle buss of your box. Be careful when tapping into your system for 110V machine accessories such as lighting and coolant pumps to avoid this center "hot" leg or you will get smoke. Also, some magnetic contactors (even 220V 3 phase ones) require 110V for the coil. Don't ask me how I know!

What is the (safe) proceedure for testing the voltage between each of the three, 3-phase wire and ground?