rotary phase converters?

NickWheeler

NickWheeler

Joined
Dec 3, 1999
Messages
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So do any of you guys have much experience with these?

Before you tell me to use a VFD, I gotta say I just brought home THREE new (to me) machines that are all three phase. One of which is an old Cincinnati mill with a 5hp motor. A VFD for that motor alone would be pretty spendy. Outfitting all three machines with a VFD would be pretty darn expensive.

I'm not real keen on building one.

There are places like American Rotary that build a 7.5 hp converter (allowing 30%+ a little extra juice) for not a hurrendous price. http://www.americanrotary.com/rotary-phase-converters.html

I don't really see negatives in the way of a ROTARY converter. Static converters seem to be prone to overheating and a loss of power.

I would like to put a VFD on the vertical mill as it's a step-pulley head and I'd like infinite variable speed...but we'll see. ;) :)


Thanks for any input/advice/etc. :)
 
Nick
Please call me regarding your need for a rotary phase converter.
I can help you out.
262-352-4796
 
Not telling you to get a VFD but you would only need one to run all three machines. That might save versus three phase converters... Then again you might be able to run three machines off of one phase converters. Dunno
 
Nick I have one and run four machines in my shop off from it. Just wire it in and then run a three phase ciruit aroun your shop and plug all the machines into it. when you come in to the shop turn on the lights and the converter and you are ready to rol. With the rotory convertr you can run one or all the machines at the same time as long as they don't exceed the total amperage rating for the line/converter. With the one you are looking at (7.5hp) you can run up to 10 hp combined hp as long as no one motor exceeds 7.5 hp. Also every motor that is running on the circuit helps to stabilize the line voltage as long as it not under load. I bought my converter shipped to me for about five hundred dollars off e bay. It was all new components and a new baldor motor.

Hope this helps.
Bill
 
Hi Nick!


Yes, I think a rotary convertor would be the best choice for your requirements. I bought a static convertor...burned up the motor on a Bridgeport milling machine.....then built a rotary convertor from online plans and it ran great. After a while, I outgrew my home built convertor and while shopping on Ebay, I found a local motor shop who was building and selling them. I called him up...he came over and built a custom unit for me. He owned a motor shop and built it from used components whiched saved a pant-load of money. We put the big rotary motor outside of the shop with the control panel and capacitor bank inside the shop. This way....when it was running, I couldn't hear a thing. From that day on...I never hesitated to buy 3 ph machinery.

So...here's the lesson to be learned: Check with your local motor repair/rewind shops to see if the old timer who has been there since 1910 is interested in building one on the side to suppliment his tanked 401K. They are fairly simple and can be made dirt cheap from scrap and surplus components. (The stuff that motor repair shops have laying around.)

Eventually I moved into a larger industrial/commercial building with 3 phase power and sold that pahse converotr on Ebay for more than I originally paid for it. It was a great investment all the way around.

Good Luck!

-Rob
 
+1 on a rotary converter. They work well. The up front investment can be higher than a VFD or static converter, but they are a better machine in the end and as previously stated a good motor rewind shop can build you one for a lot less than new.
 
Thanks guys- :)

The idea of being able to run whatever machine I may buy off of one converter is what drew me toward one. I do understand that I can't exceed the converter's limits.

I hadn't thought of the motor shop idea Rob! I had been leaning toward the idea of a ready made unit from one of the suppliers I've found (thinking it might add some accountability on their part) but I would have that with a motor shop too. Or so I think.

There's actually a place in Portland with a unit made with a used Baldor 7.5hp motor for about $500. That would get me going pretty cheap.

Thanks guys for the help and advice!!! :thumbup: :cool:
 
NickWheeler said:
There's actually a place in Portland with a unit made with a used Baldor 7.5hp motor for about $500. That would get me going pretty cheap.
Click to expand...

:thumbup:

I run my entire shop on one 15 HP phase converter. That includes CNC machines that require clean power. I've measured the wild leg while running multiple machines in heavy cuts and it stayed within a reasonable range. :thumbup:
 
any one have a wiring diagram and info on how to make a converter. I have 3ph but I have always been interested in how they worked. Most of what I have seen look like a wire explosion but there has got to be a clean way to put one together.
 
Not to hijack this thread, and sorry if this is a dumb question, but how does one accomplish variable speed control when using direct three phase power? I understand how the VFD works, just not sure about three phase. With the number of machines I want to use / convert to variable speed this sounds like a good option.

Thanks,
Dan Kaschner
 
the rotary converter will not give you variable speed unless it is already on the machine. You wpuld still need a vfd for single speed machine to get variable speed but 3ph to 3ph vfd are availible an if I am correct are cheaper than 1ph to 3ph units.
 
Thanks Bill.... funny that's the same outfit I've been looking at. Looks like Mike has one from American Rotary he's not using so I'm probably going to buy his.

Thanks for the help!!! :)
 
Cool.. thanks Bill. That makes sense. It really helps clear up my understanding and makes it easier to evaluate the costs and potential savings associated with using a rotary converter.

I appreciate the help!

Dan Kaschner
 
Nick, it was nice chatting with you as well. One mistake I made with my converter was mount it to the wall. I used rubber mounts on top of 3/4" plate to limit vibration, but this thing resonates like you wouldn't believe. I have friends with their converters on rubber mounts sitting on the shop floor and they are whisper quiet.
 
I see that people are using 15 hp rotary converters which actually are running on single phase and 10 hp is the max hp for a single phase motor. How does this work? And what is the max converter hp?
 
When I was at Kevin Cashen's shop a few years ago, he showed me his phase converter, which he made himself out of a motor. Can't remember how he did it, but I would sure like to know. Hint, hint, Kevin. :D
 
sabu386 said:
I see that people are using 15 hp rotary converters which actually are running on single phase and 10 hp is the max hp for a single phase motor. How does this work? And what is the max converter hp?
Click to expand...

There are a set of starting capacitors and a set of running capacitors (used for balancing) during running. One is paper, the other is oil I believe. The 15 HP motor is started as if it were started from a big static converter, using the starting capacitors during the wind up. It is then used with the run capacitors to generate a 3rd leg for the machinery. The voltage potential between the three legs is (more or less) equal. But the voltage potential between the individual legs and neutral are something like 120, 120 and 180V. The reason for this is the L1 and L2 are still 180 deg opposed, but the new wild leg is only 90 deg opposed to the other two legs. This power works fine for a three phase motor (which doesn't use a neutral so voltage potential is what counts) but you don't want to use the wild leg to power sensitive electronics or anything running the power to neutral unless it is designed for higher voltage (many solenoids and amplifiers are).
 
Mt two sons and I run an entire woodworkign shop with one 25 horspwr phase converter. ur largest motro we run with it is a 15 hrs for a wideblet sander, two 7.5 motors and everything works great. The phase convertoer is 8 yrs old and we turn it on when we arrive in the AM and turn it off in hthe PM when we leave. WIth light, three men working, and phase converter running all day...electric bill is about $200/month. They last forever if you buy a good one. Ours ran about 2k 8 yrs ago.
 
I have been using a rotary phase converter built using a 10 HP three phase motor I was given. I bought all the necessary components from a place on Ebay for about $100. It is really very simple to make and all components are provided including short pieces of wire and connectors. The only thing not provides is the box to put everything in. I have been running a milling machine, lathe, and metal shaper for several years now. All of these are 3 phase. Just make sure your converter is more powerful than any of the machines you plan to run.
 
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