Replacing 3-phase mtr on phase converter
JeffHeath
| Posted in Power Tools and Machinery on
RickL, where are you??
To all: I have a homemade phase converter to run my 3 phase machines. It is a 6 hp 3 phase motor, run through a couple of electric boxes to create the third leg, to start the 3 phase machines I own.
Today, the 6 hp motor cooked. It started smoking, and now, every time I turn it on, it gets real hot, and starts smoking badly.
Here’s the big QUESTION. Can I simply find another 6 hp. 3 phase motor, and replace the burnt out one, or do I need a specific type of motor to create the third leg to start 3 phase machinery.
FYI, the largest motor I’m starting is 3hp, which is half of the 6 hp in the phase conversion device.
Thanks for the help.
Jeff
Replies
Jeff,
I do not know enough about motor to discuss this intelligently; however, I do not feel you have to have a motor identical to the one you have. I feel if it is the same type, voltage, and RPM, you should be okay.
Below is a forum in Practical Machinist that will have your answers. If you cannot find your answer and do not want to join, I will post the question for you.
You should be able to find a 6 hp motor for little of nothing on eBay. If I recall, the idler motor on your phase converter should be twice a large as the motor you are powering. I have two phase converters and I have not had to work on either one of them. I would make sure the problem is originating in the motor and not caused by some other component. It would not be fun to replace the idler motor and watch it fry when you turn it on. I watched an 8kw generator smoke, right out of the box, once and it was a sickening feeling.
Grits
http://www.practicalmachinist.com/vb/forumdisplay.php?f=11
It's not always easy "finding" an exact replacement at the right price. Free or cheap. 6 hp is a Euro motor. I'm guessing you made up your own static to start your slave motor. If using a different hp slave motor you will need to resize your starting capacitors. The slave motor generates the third leg although it's typically a lot higher voltage. Try reading info at http://www.phase-a-matic.com They have a lot of info on making the rotary with a slave motor and static converter. Also Rick C at http://www.waterfrontwoods.com has a lot on making and balancing converters and he seems to want to help people so they don't kill themselves electrically.
Good luck Jeff
Rick L
Rick and Grits:
Thanks for the info, guys. I'll check these sites and figure out what I need to do.
Jeff
Rick
Your advice was spot on. The motor I had was a 6 hp Toshiba. I couldn't find a 6 hp motor (3 phase) anywhere, and I need my jointer daily, so I just bought a brand new 7 1/2 hp rotary phase converter from American Rotary. Baldor motor, american made parts, and it only cost me $420.00. It'll be here Friday. Thanks for the help.
Jeff
Consider a VFD for future applications. Especially on shpers drill presses, lathes. You canget infinitely variable spped, slow start, etc. On motors 1 hp and less you can get ones to run on 120 volt. http://www.factorymation.com You need to call the tech to get the right one. Some have be derated for the application. If you try reading the specs on the site you will make some wrong assumptions if you don't get guidance from the tech.
That's not a bad price for your rotary. It's been my experience to not buy Rotary converters direct from the manufacturer. Other sources typically sell them for less. Enco has good prices on Phase-a-matic for example.
I found this company off of ebay. They had a toll free # that I called, and I spoke to a guy who really knew his stuff. He asked what I would be running, and what I might be running (motor size and tool) in the future, and recommended the unit I purchased, which will run any of the tools I listed up to 5 hp, 3 phase.
Their feedback was 100% with 892 transactions,and they gave me a 1 year guarantee, 100% refund if not satisfied. That was good enough for me.
Thanks for the help,
Jeff
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