Rotary Phase Converters

shortbusdriver

shortbusdriver

this guy
Joined
May 17, 2009
Messages
2,318
Looking at picking up a used 10 ish hp rotary phase converter. I have never delt with something like this before and looking for pointers in what to check over on them to make sure they are alright if it is not wired to a machine and in operation. Looks like I can save around $400-$500 by going used instead of new. I don't have the time to build one either.

I picked up a 5hp 3 phase machine that I would need it for. I live in bum fuk no where and cant get 3 phase power in and wouldn't be using it on a daily basis anyways so figured a rotary converter would work the best. I want to go a bit bigger then what I need at the moment so I don't have to upgrade down the road if I get another larger machine.
 
Motor should start and run. Without load connected.

Open covers and make sure capacitors aren't exploded

It should have a start bank and a run bank with a timer relay of sorts.

What else do you want to know?
 
Because there is so many different ways to build a rotary converter.
Just make sure that the wiring isn't burnt or frayed and all is connected securely and safely. Spin motor over by hand and listen for bad bearings.. grease may quiet it down but if bearings are bad forget it..
Would be better buying kit off eBay.
 
So you are saying the the little motor on a plywood frame spinning the giant ass motor to start it was no-bueno? :D

My first ever employer bought a refer unit from a burnt restaurant to keep his ice business well stock. No 3 phase so they installed a monument to redneck electrical prowess. My life and the life of a few others were threatened so we would never mention what we saw.
 
I started mine with a pull rope wrapped on the sheave for the longest time..
Like pull starting a lawn mower.
Just saying, once you have the motor the hard part is done.
The control box and panel board make it nice to use regularly.
 
Save your money and get a VFD for phase conversion. No comparison how much better the frequency drives work.
 
What's the legality surrounding them? I know the one we had wasn't supposed to exist.
 
legality depends on osha. . LOL

VFD's cost a lot more than 600 bucks..

You are right they do better, but cost vs function is not in the wallet for a lot of people.
 
SINNER said:
Save your money and get a VFD for phase conversion. No comparison how much better the frequency drives work.
Click to expand...

I had actually talked to someone about him building me one if I got a 440V machine since I only have 220V available.

Can you suggest one for my 5hp 220V application. Looks like they are fairly reasonable on ebay but have no idea what a decent one goes for.
 
And as expensive as they are, they dont exactly "fall off the back of trucks" often, or get "misplaced inthe inventory system" at all.
 
ComnRailPwr said:
VFD needs to be twice the size of the load from what I heard.
Click to expand...

no, its rated at the hp required,
its the transformer that needs to be about 1.57 times larger than the expected load.

for instance, 50hp water well needs a 50kva single phase transformer running through a vfd, but a three phase bank can get away with 30kva worth of transformer
 
Actually he is partially right. I called 2 different drive suppliers and it seems they have smaller units built for converting 1 to 3 phase. These seem to be limited to around 3hp/11amps however.

To go bigger they said I would have to get a 3 phase input unit, but have to take my machines hp and double it to provide the power I need.
 
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