Phase Converters

[Greg in Maryland]

Hi

I have my eye on a old Clausing Atlas Table Saw that is powered as such:

3HP,
220/440v,
3PH

I have a 220 line in my basement, but only single phase. I have heard of phase converters, but really don't know enough to make a reasonable decision about purchasing the saw.

If I were to purchase the saw, what type of phase converter would I need and what are good sources? What is a typical price?

Alternatively, what are good sources for 3 hp single phase motors? What is a typical price?

Thanks.

Greg

[Daryl]

There are two; types of converters, static and rotary. The rotary will give full time three phase, the static will only provide the third phase upon start up. While a lot cheaper, the static will only provide two thirds of the rated motor power. Another down side of the static is that it doesn't always give the starting kick, you have to be on your toes to turn the power off or burn the motor out.

[Tom Slick]

Another option is a Variable Frequency Drive or "AC Drive". They convert 1ph to 3ph electronically and you can vary the motor rpm with it.
Here's an example of a reasonably priced model.
http://www.automationdirect.com/adc/...AC%29/GS2-23P0

[LCHIEN]

Another option is a Variable Frequency Drive or "AC Drive". They convert 1ph to 3ph electronically and you can vary the motor rpm with it.
Here's an example of a reasonably priced model.
http://www.automationdirect.com/adc/...AC%29/GS2-23P0

That's probably the best solution.
And it weighs a whole bunch less.

[lago]

I recently restored an old 8" Delta jointer that had a 3-phase motor. I went with a AC drive from www.factorymation.com. Cost was about $150 + shipping.
http://www.factorymation.com/s.nl/sc...egory.15366/.f

Be sure to check the wiring on the motor. Mine was wired for 460v and I had to rewire it for 230v.

Lago

[Greg in Maryland]

Thanks for the replies and the education.

I read the manuals and installation guides for the "AC drives" and it makes my head spin. I gather that the AC drives are hard wired into the electrical panel and then the saw is wired to the AC drive. So, one AC drive to one phase 3 motor, correct?

There isn't a way I could handle this installation, so an electrician it would be. Would a typical electrician be able to handle an AC drive install or would I have to find one who specializes in this?

Alternatively, can a rotary phase converter be easily switched from machine to machine, much like a dust collector? Obviously motor size would be a factor.

Lastly, by the time I purchase a phase converter/AC drive/electrician, it might be cheaper to buy a single phase motor. I have looked at Grainger's, but are there any other good sources out there?

Thanks.

Greg

[Daryl]

Yep, with a rotary converter you can run multiple machines at once as long as you observe the power limitations. You would just run a three phase circuit to each machine, as long as the converter was running you would just flip the power switch for which ever machine you were running.

[Tom Slick]

The AC drive would be installed on your machine, at each machine as it would take over the on-off controls. An electrician would be able to install it, they are easier to program than it seems. Programming is very logical and linear thinking. Programming for a table saw would take 5 mins and I could walk you through it here.

They are also silent, a rotary phase converter makes a lot of noise.

Caveat: if you do go with an AC drive, your on-off buttons/switch would be wired into the AC drive, which is still easy and completely covered by the installation instructions. If you leave the switch between the motor and AC drive it will destroy the AC Drive. I can help you with any wiring questions.

[Greg in Maryland]

Thanks.

Thanks for all the replies and information. As it turns out, the auction price fore the table saw exceeded what I was willing to pay. Especially since a phase converter of some sort was required and the arbor size was 3/4. Instead, I picked up a Ridgid TS3650, which I hope will keep me in the sawdust for years to come.

Greg

[toolguy1000]

Thanks for all the replies and information. As it turns out, the auction price fore the table saw exceeded what I was willing to pay. Especially since a phase converter of some sort was required and the arbor size was 3/4. Instead, I picked up a Ridgid TS3650, which I hope will keep me in the sawdust for years to come.

Greg

good move. the 3650 is a very good table saw. for plans on a really good outfeed table, check this thread from the ridgid forum:

http://www.ridgidforum.com/forum/sho...eed+table+3650

you lucked out not getting the 3phase motor saw. 3 phase is primarily designed for industrial/production environments where continual operation is the norm. the on/off nature of power tools in a home shop is really contrary to what 3 phase is idealy suited to.

[Greg in Maryland]

I saw that thread and numerous others, so the plans are forming .... Unfortunately, the planning stage is a bit quicker than the prototyping stage.

Greg

[woodturner]

3 phase is primarily designed for industrial/production environments where continual operation is the norm. the on/off nature of power tools in a home shop is really contrary to what 3 phase is idealy suited to.

Never heard that before - would you please elaborate? From an engineering perspective, I don't see a rationale to support that argument - and three phase motors are often used in applications where they are frequently started and stopped (like plastic injection molding machines).

[Tom Slick]

Never heard that before - would you please elaborate? From an engineering perspective, I don't see a rationale to support that argument - and three phase motors are often used in applications where they are frequently started and stopped (like plastic injection molding machines).

I haven't heard that either. 3ph has no start circuit to wear out for one thing.

[LCHIEN]

Some excertps from the Wiki article on three phase:

A three-phase system is generally more economical than others because it uses less conductor material to transmit electric power than equivalent single-phase or two-phase systems at the same voltage.[



Three-phase has properties that make it very desirable in electric power systems:

• The phase currents tend to cancel out one another, summing to zero in the case of a linear balanced load. This makes it possible to eliminate or reduce the size of the neutral conductor; all the phase conductors carry the same current and so can be the same size, for a balanced load.
• Power transfer into a linear balanced load is constant, which helps to reduce generator and motor vibrations.
• Three-phase systems can produce a magnetic field that rotates in a specified direction, which simplifies the design of electric motor

============

Three phase motors probably have no problem more than single ph motors starting and stopping frequently.
They probably do better if anything - no starter circuit makes them more reliable and starting torque may be better due to the rotating field.