PDA

View Full Version : What has been done to this motor: Lincoln Electric 3 Phase Motor running off 220v 1ph



geardoc
10-07-2012, 05:16 AM
I purchased an odd ball compressor to get the pump for a gasoline powered compressor I've been building. When I first got it, the it was wired up, it was wired, running a standard 220v plugin for power, and the place I purchased it hooked it up to 220v and it ran fine and powered the compressor. It was very obviously 1720rpm motor though, and the compressor pump was needing more RPM's.

So when I was done making my new gas compressor, I got to looking at the very obscured data plate and noticed the diagram for the wiring. It looked like diagrams for 3 phase arrangements.

So I cleaned off the data plate, and while much of the paint was missing, I found out it is a 20 year old or so Lincoln Electric Motor and it is marked 3 phase, it is also marked as 220v/460v that I can see. It also says something about 208v but the paint is very badly missing there

Looking at the way it has been wired, it has no phase converter of any sort, it doesn't look like it has any special caps to get it to start and run with 220v as well as it does.

Any idea on what was done to this motor ? Is it possible someone used the frame and housing and had a 220v single phase motor rebuilt out of the old frame ?

I'd like to have it for a rotary phase converter for some of the smaller 3phase items I may have in the future, but I'm not sure what has been done to it.

I thought if a 3 phase were wired up to single phase without the caps, it would either not run, if it did run it would be several underpowered and run very rough and generate a lot of excess heat. This one runs quite well, a tach I have for measuring speeds of moving shafts says it is running 1700rpm or so(the tach is a hobby tach for propeller speeds, etc).

Thank you for your help.

lane
10-07-2012, 04:58 PM
My guess is they were running it on 220 3 phase . Just had a rigged up plug are something . They may have been running the ground wire as a hot 3rd. leg . I have seen lots of get it done to run jobs left un finished correct. Without a phase converter some where the 3 phase would not start a compressor.

The Artful Bodger
10-07-2012, 05:50 PM
I am just thinking here....... to start the motor requires some difference in phase between windings, this can be had from a multi phase supply, obviously, or by introducing reaction either capacitive or inductive.

Single phase motors with capacitors are obviously using capacitive reactance for starting and maybe for running too.

In this case, some clever kludger may have found a way of connecting some coil(s) in parallel and some in series, those in series would have more inductance (and inductive reactance) and consequently the voltage phase in those coils would have a leading phase.

J Tiers
10-07-2012, 08:53 PM
You KNOW it was hooked to single phase?

I ask because the plug doesn't prove much... you can use any plug you want that is rated for the voltage to ground and the current... so long as no other plugs of the type run on a different voltage, so nobody can get confused. 4 wire 220V plugs are used in some places for 3 phase, legitimately....

geardoc
10-07-2012, 10:46 PM
I opened it up today. It's a nightmare.

I figured it would be.

It is a TEFC housing/frame with a non-TEFC inside.

Sigh.

Now I think I'll go check the compressor pump more carefully.

winchman
10-08-2012, 03:02 AM
They probably thought it was a genius solution. "Hey, I can put this single-phase open frame POS motor in this Lincoln 3-phase TEFC case. It'll run long enough to sell the compressor."