Polar cutter phase conversion

Hello… I recently acquired a polar cutter that works like a dream (in the shop it is coming out of). It is a three phase 58EM, and I only have single phase in my studio. Does anyone know if it can be modified? If I change the motor for a single phase, does it end there? I think the cutter was optionally available as single phase when new…
Anyone do this before?
Any options beyond phase converter or vfd?
Thanks for your help…

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a new single phase motor will prob cost much more than a VFD. if 3 ph were available near by, it might be worth wiring in. 3ph, down the road would be cheaper.

When I was in the trade we had a Polar, mostly used to get the stock true square before printing to make for good register, and I’m sure I recall the start up switch had three positions, OFF, a middle position to be held for a minute or two whilst the flywheel reached running speed, and then a third position sort of ”fully ON” and only after reaching that switch position was it OK to start cutting, to ‘strike on’ as they used to say. But what I don’t recall is wether we had single or three-phase feed. This is UK so it was 240 volts 50 cycles AC. I do recall that we got our Heidelberg engineer to wire it up, being ‘funny and foreign’. Same was true for Heidelberg cylinder presses, UK jobbing ‘sparks’ were out of their depth on them. .

VFDs - I’m currently shopping for a VFD, and a friend pointed to 3HP units on ebay for less than $100, and 5HP units for a bit more. Made in China, of course.

You need a phase converter not VFD

I’ve always used rotary phase converters, but other list members have suggested static converters. Less efficient than rotary, but for a cutter, not a big worry.
The larger rotary converter I got to supply a Heidelberg cylinder is very noisy when not under load. You would not want it inside your work area.

Nick, I am curious why you say not a vfd. They
are cost effective, quiet, no power loss, and provide the needed conversion to 3 phase.

A vfd is a phase converter.

Vfds rectify AC into DC then they synthesize 3 sign waves 120 degrees out of phase with each other.

The part of it that allows frequency adjustment is a feature that would not be used in this case.

Nothing is as good as real 3 phase, but if it’s not available, you need to make it. Rotary converters are expensive and noisy, but if you’re good with electricity and have the parts, you can make one yourself. VFDs are less efficient, but also less expensive, quieter, and offer speed control. Each workaround has advantages and disadvantages. Choose your problem.

vfd is needed in speed related situations. In this case its adding third leg and easiest way is with small (static) phase converter. We’ve even used them on Heidelberg OHC presses. The brains of the machine need only single phase , just main motor and backgauge motor needs 3 phase.

I understand what you are saying, and am not familiar with a cutters hp needs. It makes sense for me that when you don’t have 3 phase at your shop, and you only have one piece of equipment that needs it, that a VFD is a good potential choice. You get 3 phase without the noise of a rotary and without the power loss of a static. True, you are not taking advantage of the speed control feature, but, it has other nice features all of which can be programmed into it. It’s especially helpful if your piece of equipment is from Germany or Italy as many of their motors are delta wound and if you put a static on them you lose 50% of the motor hp, not merely 33% of a wye wound motor typically found in this country. I am not real comfortable with either of those power loss percentages. I have a new press(German) I need to provide 3 phase for it right now. I’m going VFD even though the press already has a speed control on it. The static scares me for my application. I guess, to each his own.


Vfds are more efficient than both static and rotary phase converters.

I’m lucky enough to have 500amp 3phase service in my shop, but after screwing around with what even cheap vfds can do I’m sold, the days of worrying about having 3vphase avavlible are gone.

In the case of my building a phase converter would probably be required for a 3 phase paper cutter just to clean up the power enough to run the digital electronics side of the cutter.

In my opinion static converters are dead.

And the uses for rotary phase converters are becoming less and less of a common thing below say 30hp


temco phase converter I got one for under 50 bucks new from manufacturer works great

1 phase to 3 phase conversion with VFD, I think that is the way to go: