As usual one more time I seem to be the outlier. I keep seeing threads where people are discussing the pros and cons of different power sources, i.e., rotary phase converters, VFD's, and static phase converters. I have four three phase machines in the shop and each one runs off its own static phase converter. I doubt I have as much invested in all four static converters as it cost to purchase a single VFD, and certainly far less than it costs to purchase and install a rotary converter.
The Bridgeport has been running the longest on a Phase A Matic static converter at just short of 20 years, the Racine power hacksaw is next at 10 years, then comes the Sheldon lathe at 7 years. Both are running on American Rotary brand static phase converters) and finally the Black Diamond drill grinder at 5 years (running on a North America brand static converter. All of the machines have been run hard for extended periods. The mill and lathe have worked in excess of 40 hours a week. None of the machines have ever lacked for power or overheated. They all just work as they should, when they should with no problems. While there is supposedly a 1/3 reduction in hp that each machine can put out, I've never run into a situation where any of the machines have needed more than what is available.
A side note about North America Phase Converter Co. It Is now owned by American Rotary. Up until about 10 years ago American Rotary made both rotary and static converters. At that point they purchased North America Converter and discontinued making static converters under the American Rotary brand name.
As I see it one advantage of static converters over VFDs is that all of the machines can use their original control stations. The mill and lathe have infinitely variable speeds. The power hacksaw changes speeds with a belt, and the drill grinder is single a speed. With this setup all the motors can put out appx. 2/3 their rated hp regardless of speed.
When I purchased the lathe, it came with an almost new 15 hp North America rotary converter. I had every intention to wire it up and run all the machines off it. When I started putting a pencil to the cost, it was more than I was willing to spend for little or no foreseeable benefit. In addition to the conduit, wiring breakers and box, I would also have to add another sub panel. The cost was quickly approaching $1,000.00 for parts alone. Estimates for having a contractor do the work were close to triple that amount.
Please explain to me what I'm missing. Did I just happen to pick a number of machines that run fine off static converters, or are there some unknown to me reasons it would be advisable to switch to a different power source?
One note about Phase A Matic converters. They are about the most expensive of the bunch. North America offers their PL-5 "Pro Line" converter for $615.00 plus $40.00 flat rate shipping. That includes a 10-year parts warranty, and a lifetime labor warranty. Something to think about.
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