ROTARY PHASE CONVERTER WITH TWO IDLER MOTORS ?

Hello Reeltor,

It's certainly worth giving it a try. I have often wondered how to wire my machines to achieve a higher overall RPC hp rating by turning on an additional machine. I do happen to have a 3 phase breaker panel, that I have yet to hook up, but if I do hook up my 10hp RPC to the 3 phase breaker panel, and then feed my machines with separate feeds and breakers from the panel, would I achieve the desired effect?

Brian
 
Brian,

I don't think so. If you are on separate circuits (breakers) I don't think you get the desired effect. I am not the electricity expert to ask. There are many here on the site who are real experts and can give you the benefit of their knowledge. I have all of my three phase machines daisy chained from my RPC. Breaker at the panel box and fuses or breakers at each machine. From the get-go I put in a large RPC (15hp) box from WNY phase convertors and a NOS locally sourced motor. In your case, I'd try to make what I have work and not re-spend money already spent, at least try to use what I have until conditions prove unsuitable.

Mike
 
Hello Reeltor,

It's certainly worth giving it a try. I have often wondered how to wire my machines to achieve a higher overall RPC hp rating by turning on an additional machine. I do happen to have a 3 phase breaker panel, that I have yet to hook up, but if I do hook up my 10hp RPC to the 3 phase breaker panel, and then feed my machines with separate feeds and breakers from the panel, would I achieve the desired effect?

Brian
Using that 3 phase panel would be a great idea. and yes, all the motors help generate 3 phase. For many years, I started my drill press and left it running to start my big lathe.

There is no exact rule for how much 3 phase motors are needed to generate the 3 phase circuit. everything depends. Just remember if you are undersized and start too heavy a part in your lathe at too high a speed, lots of majic smoke will come out.
 
Well, I found a 10HP 3 phase motor to replace the high voltage one on the lathe, for a start. I just got home with it, so I haven't checked if it runs, without issues. It is a dual voltage Baldor motor 208-230/460V , 1725 RPM and the same 215T frame size as the one on the lathe. The 10HP 3 phase motor on my RPC is a Canadian made Leeson motor with exactly all of the same specifications. Although, the Baldor motor lacks the cast cooling fins, it still looks like a TEFC motor.

Here's a few pics of the motor...

IMG_0397 (1024x768).jpgIMG_0398 (1024x768).jpgIMG_0396 (768x1024).jpg


Here is the RPC motor...

IMG_0391 (1024x768).jpgIMG_0392 (1024x768).jpg


So, now I have a choice of motors for the lathe.

Brian
 
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I just noticed that the frame designation on this new motor is 215TC and the other two motors are 215T. I believe that the letter "C" refers to the new motor being able to foot mount, or face mount.

Brian :)
 
Things to know on multi motor RPC setups.
First and MOST IMPORTANT the motor RPMs should match and motors should be of a similar design. Don't mix winding types.

After that, it's simple.
Build your standard single motor RPC, with a starting method of your choosing.
Then you need two additional timers and contactors.
Once the first RPC is fully up to speed and running, have a contactor connect the second motor, do this with a timer that runs longer than it takes for the first motor to start.
Once the second motor is running and up to speed, have a second contactor connect the output and run capacitors for the second motor.
Easiest way to do this is have the first timer start to second running and have it control the contactor for the output. Wire the run capacitors to the OUTPUT of that contactor as well as the actual output to the equipment.

Have done a couple that were in excess of 100HP total capacity off a 20 a 30 and a 50 HP motor.
Big 3 phase motors simply can't be started with the capacitor start method. The current draw is crazy high.

Remember that your wire sizing will need to be rated for the TOTAL HP output of the complete RPC unit. Meaning is you are gonna have 20 HP total output, the wires coming from the breaker box and going through to the output will need to be heavy enough for a 20 HP load.
 
Hello Keith,

Thank you for all of the very helpful information. I am still on the hunt for a third 10HP motor. I will be heading down to the shop soon, to check the motor that I bought, to see if it is a Wye or Delta connected motor, as well I will hook it up to my RPC to see how it runs and what voltage values it produces. I will also check my RPC motor, to see which way it is connected, as to Wye or Delta.

I am fine with those fundamental procedures, but I may have to have some help when it comes time to wire in the second motor and contactors, etc.

Just so you guys know what it's like trying to find an electric motor of this specific size, in my area, I had to cough up $250.00 for this one that I bought yesterday. If I could have found one at the scrap yard, I would have paid $200.00 for it. I had one guy answer my "Wanted" ad, who wanted $550.00 for his motor.

Brian
 
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I have a NOS Hobart control panel, that might be of some use for the second motor, but I fear that it may not have the capacity in amps. Here's a few pics of it and the schematics...

IMGP0893 (800x600).jpgIMGP0896 (600x800).jpgIMGP0900 (600x800).jpgIMGP0906 (800x600).jpgIMGP0907 (800x600).jpg
 
Well, the used motor that I bought, looks like it has a bad winding. The fellow who sold me the motor, says he will refund me the money spent, but we shall see. All of the scrap yards, simply cut the motors off of equipment and toss them into a pile, so, unless you are right there when a piece of equipment comes in.... and it has just the right motor, you are SOL...

So, I called a local motor repair shop and ordered two motors. From what I understand, the Leeson motor is a re-conditioned motor, and the Ech Top motor is new.

IMG_0432 (1024x768).jpgIMG_0433 (1024x768).jpg

So, now I have three good 10hp motors to work with. They are all 230/460V motors, and, I believe, all are the same winding types. The two new motors are both rated at 1760 RPMs, as well, my older 10HP RPC motor, is
rated at 1760 RPMs



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So, I will go the route of using the two 10HP motors combined, to give me the equivellent of a 20HP RPC, and the third 10HP motor will go on the lathe.

Brian
 
Well, it's been a while since I last posted.... I ran across a thread, which gave a link to a Phase-A-Matic bulletin, which shows two identical HP RPC's wired together in parallel.

http://www.phase-a-matic.com/PDF/RMU.pdf

I am tempted to go this route, to achieve a 20HP RPC. For the price of another complete RPC panel from WNY Phase Converters, I don't think that I could source, collect, and purchase all of the parts individually for that price. In addition, down the road, I can always sell each 10HP RPC's as complete.

What do you guys think ?

Brian
 
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