Advice needed on phase converters

[wood_newbie]

I'm looking to upgrade some of my shop equipment, and I'm tired of the lousy quality control and metal casting coming out of Chaiwan. I'd love to buy American/Canadian, but the remaining manufacturers are priced so high they're out of my ball park.

In looking at much of the used Oliver/Northfield/Yates equipment for sale out there used, the vast majority seem to be three-phase motors. Working out of my home, that would mean either replacing the motors or getting a phase converter. I could get into a static converter for about $200 - $250, but then I'm looking at 70% max power.

I'd prefer to go the rotary route, but of course, then I'm looking at $600 - $700 for even a small unit.

Can anyone tell me about their experience with such a beast? I know the "quality" of the power coming out of a rotary is still not as good as true three phase, but does this cause any damage to the motors over the long haul? Are there any other headaches they present?

Thanks in advance.

[Tom Gardner]

Go to rec.craft.metalworking, they are the RPC gurus

[Charley]

Rotary phase converters are the way to go if you will have more than one 3 phase tool. You will only need one converter big enough to run your largest machine if you will only be running one machine at a time. The output isn't really 3 phase, but it's close enough that the motors don't care. I have several print shop customers that have been running their presses on rotary phase converters for years without having any more motor problems than customers who have real 3 phase. Keep in mind that they take more (about

140%) single phase current input than the 3 phase output current, so you will need to budget your power for it. A transformer will draw almost no power when no load is connected and rotary phase converters are similar, so it is common to turn them on at the beginning of the day and off at the end of the day. The 3 phase tools are then always ready for use. If there are any control circuits in the tools that run on single phase (2 of the 3 phases) be sure to hook them across the 2 non created phases of the converter's output.

E-mail me direct for more info.

[wood_newbie]

Good advice...I just took it. Googled the group first, but most of the info on it went so far over my non-electrical head I could have used my spinning head as a rotary converter!

So I posted the question with a caveat that, I'm electrically ignorant, please be kind.

BTW, one of the reasons I'm starting to look down this path is your recent auction post. I would give my ( __ ) to have that 36" Northfield, but I've got nowhere to put a nine-foot-tall, 2700 lb. band saw other than my backyard! (And even it might collapse under the weight!) Now, if you were selling a 20" Northfield, I'd be all over it like s**nk on a Britney Spears!

Good luck on selling your babies. And here's to them going to a good home.

[wood_newbie]

One other thing...I noticed someone asked you what the resaw capacity was, and you replied that you didn't know. Certainly a fair question, but by looking at the picture, I think you could just have safely answered something like "Honda Civic."

[Juergen Hannappel]

[...]

You can also use a rotary converter to buffer power surges, so that the average input power is less than the peak output power, due to the energy stored in the flywheel. Look here for a biggie:

[Charley]

Motor - generator sets and rotary phase converters ARE NOT THE SAME. While it is indeed true that the flywheel of a motor - generator set will buffer power surges and sags, a rotary phase converter will not. Rotary phase converters don't have a flywheel and they don't have any generating capability. They are nothing more than a rotating transformer and most don't even have an output shaft.

I built a rotary phase converter out of a large 3 phase motor for a home shop. It has been running for over 35 years, providing 3 phase power to a Bridgeport milling machine, a Cincinnati lathe, and a horizontal mill. It's large enough to allow any two of these to run at the same time.

[Tom Gardner]

Printed and posted on my bulletin board! We had a good laugh, thanks!

[Jay Pique]

At what point does dedicated three-phase service become cost effective? Transformers are pretty pricey for the initial install I've heard. A site for 3-phase like Bill Pentz did for dust collection would be excellent. Any takers?

JP

[Pat Barber]

One thing to remember.. Three phase is almost "never" available in residential areas. It is also fairly rare in "light" industrial. It just depends on your area and your power company.

Three phase typically uses a "demand meter" and that can be right pricey.

That's the reas>