Phase converters - 3 to 1

[norml]

Is it OK to use a phase converter from 3 phase to single phase?
I know their is a loss of horsepower but is that important?
If I buy a 3 phase machine and use the converter to single phase am i OK?

[Baer Charlton]

I think the Electricians Forum is Shocking.com :eek:

wouldn't you really want to be asking an electrician?

[EllenAtHowards]

I thought it sounded like a Star Trek type question...

[Ron Eggers]

Baer and Ellen: You should both be ashamed of yourselves. This is clearly a Picture Framing Business Issue.

[norml]

Thanks, Ron
I need to make a decision on buying a used machine. The company who is selling it of course say it is OK.
I need to know for sure.

[Ron Eggers]

Norml, the serious answer is this: We don't know.

We don't know what kind of machine you're talking about and, if we did, it probably wouldn't help.

If we knew about this stuff, we'd all be pulling down the big bucks as licensed electricians.

Having said that, there's probably a good chance that someone will chime in with an opinion.

[Mike Labbe @ GTP]

Not to disappoint Ron smile.gif

Three phase is far more efficient for motors, and the converters don't offer the same quality power as having the electric company pull some new wires to your shop. But that could easily cost 10k+. Sometimes its free, but you would still need to have an electrician wire it to a new panel in your shop, and to the equipment.

Using a phase converter may also void the warrantee of your equipment, and you need to make sure its rated high enough for the demand. I would also check with the equipment vendor to see if the equipment will WORK with a converter. (rotary, static, or VFD) There can be balancing requirements for each leg of the feed.

Jay_H is a licensed electrician, I believe, and may have more(better) info. I'm only licensed for video, audio, alarms, data, and phones. I'm NOT one, so use my advice at your own risk. You may want to consult with a professional locally, in addition to the vendor. This is an advanced topic many(most?) electricians will not be familiar with.

There may also be the option of replacing the motor so it runs on 110/220.

Good luck,
Mike

[norml]

Ron & Mike

The machine is the PISTORIUS MN-200

[Jay H]

I don't understand the question!

If you have 3phase then you have single phase (which is actually 2 phase for some reason)already. There is nothing to "convert".

The longer I'm away from electrical work the more it fades. This is really bothering me becuase I went to school for 5 years and it all seems that its becoming for nothing.

[norml]

The moter is 3 phase and the electric in the shop is single.

[Jay H]

Originally posted by norml:

If I buy a 3 phase machine and use the converter to single phase am i OK? Ok...I guess I missed that.

People do it all the time. There are two types of converters one that mocks the third leg and one that that just charges the third leg until the motor gets running then drops the third leg.

Both run on limited horsepower (about 1/3) but if the load is large enough the motor won't even start using the first type. I'm guessing you will need the second. But keep in mind that I only installed them. An engineer or shop ordered/sized them.

For my own personal use, I always swapped out the motor.

I just checked on ebay and it looks like they run about $300-$400 but I would want to be certian I was getting the right size/type. Get that info from an electrical supply house or better yet let a contractor install it.

One thing to check is how full your panel already is. The main problem we had installing them is that you need a breaker 2 times what the 3phase load is. So if you need a 20 amp breaker you will have to install a 40 amp for the converter. It wasn't uncommon to find that it would overload the panel. Then by the time you install subpanels and/or upgrade services blah blah blah you might wished you had spent your money on a vactaion instead of a saw.

I would still check and see what a single phase motor will cost becuase converters are still hard on the equipment and motors are easier to install. I'll even bet pistorious could direct you to a company that will sell the right motor.

[kra]

norml
I have been running 3 phase equipment in my woodworking shop with a homemade rotary phase converter for many years with no problems at all.
2 table saws, radial arm saw, shaper, planer, punch press, and lathe, all from one rotary phase converter that will run 3-5 hp motors at the same time. If it is sized properly and tuned for the 3rd leg you should not have any problems.
Not hard to build a converter cheap but easier to buy one
kra

[Jerry Ervin]

I run a Ledsome saw on a rotary phase converter and have had no problems at all.

I bought a larger unit than the amps needed. I paid $750 plus shipping. The power company wanted eight grand to add a second transformer to the pole and swing a secondary pull to the building.

I tried an inexpensive static converter with poor results. I would highly suggest a rotary.

[Jim Miller]

Phase converters are OK unless you are operating near ther amperage limits of the machines.

If you have a commercial storefront, the main electrical service outside is probably 3 phase. If so, it might be less costly to have an electrician run it into your shop.

[Rogatory]

I had the electric co. check out the lines when I first opened. They were surprised that there WAS 3 phase in our neighborhood, but the closest line is on the other end of the shopping strip. They gave me an estimate of $13k to run it to my place.

TEMCO (http://www.phaseconverter.com/static-converter.html) helped me out. Give em a call their top notch. Temco seems to have a summer sale on the 6000 series.

Jerry's right, get the rotary.

[Warren Tucker]

Norml, we have 8 three phase machines running off a rotary converter plus a three phase battery charger. There are two kinds of converters: static and rotary and rotary is the more efficient. You need a converter rated for the hp of your largest motor. it doesn't matter how many motors are runnng at the same time (because any three phase motor running generates the third leg.

There is a small decrease in power, but it's small and can be ignored in most applications. The big negative is that you don't get the energy savings possible with real three phase.

Find out how large the motors on the machine you're considering are and get a converter 1hp (it's actually a three phase motor with capacitors for starting) larger than that motor to be safe.

Our largest motor is 7 hp and we use a 7 1/2 hp phase converter. Once the converter is wired up, it's pretty much transparent. We've been using one for over 10 years with absolutely no problems.

Warren