Roatary Phase converter ??

[muddstopper]

Pretty sure I am not mixing up the starter/pony motor with using another motor to clean up the power. If I am reading right, a pony motor is just a motor used to get the bigger 3phase motor to turning before turning on the single phase power. The pony motor is just used as a starter instead of running a large starter capacitor. The article about running another motor in addition to the rotary is supposed to make the phases more in sync or something. The more motors you are running the cleaner the power. I other words, if you had 3 or 4, 3phase machines running off one RPC, turning on all the equipment, even though you only plan on using one piece, would make that one piece you are actually using have a purer 3phase power, Or something along those lines. Of course , I dont fully understand it. I have only had a couple of days of reading to learn about this stuff. Wait!, a couple of days of reading makes me a internet expert already. What was it you where needing to know??:laughing:

 

[Kyle_in_Tex]

My boss' RPC has the old shaft sticking out one end of the big motor. He just puts his tennis shoe on it and gives it a spin in the right direction and then turns it on.

 

[ultrarunner]

Single phase is the standard over here, usually 240v. Do you have 3ph in your homes in Norway? What voltage?

I have 3 phase in the cabin in Austria... also have a Siemens continuous flow on demand hot water heater...

 

[newbury]

Pretty sure I am not mixing up the starter/pony motor with using another motor to clean up the power. If I am reading right, a pony motor is just a motor used to get the bigger 3phase motor to turning before turning on the single phase power. The pony motor is just used as a starter instead of running a large starter capacitor. The article about running another motor in addition to the rotary is supposed to make the phases more in sync or something. The more motors you are running the cleaner the power. I other words, if you had 3 or 4, 3phase machines running off one RPC, turning on all the equipment, even though you only plan on using one piece, would make that one piece you are actually using have a purer 3phase power, Or something along those lines. Of course , I dont fully understand it. I have only had a couple of days of reading to learn about this stuff. Wait!, a couple of days of reading makes me a internet expert already. What was it you where needing to know??:laughing:

OK, yes you have it right. As I understand it if you have several motors on 1 RPC you start the RPC, start the biggest motor, then start other motors and somehow it improves the power.
Just don't let the smoke out.
Frome Phase-A-Matic's web page:

The first motor started, if not running heavily loaded, generates additional 3-phase power back into the circuit. You can then run additional motors, provided they are not running heavily loaded and not all started at the same time. A maximum of up to 3 times the HP rating of the Rotary Converter can run at the same time, if not heavily loaded, and not started simultaneously. For example, a 30 HP Rotary Converter potentially could run motors totaling up to 90 HP. Contact factory for verification of sizing.

 

[ultrarunner]

Just to add...

30 years ago I bought a NC Bridgeport Tape Mill and set it up in the garage.

For 30 years I have been using a 1 hp 3 phase electric motor with a rope start for my 3 phase power source.

About 20 years ago did the same for a 3 hp compressor with a 3 hp pony motor...

So far... zero problems and the Bridgeport has runs 8 to 10 hour days for several days at a time... don't use the big compressor much unless sandblasting.

 

[Big Barn]

I'm fortunate for the fact that we've had 3 phase here on the farm since the mid 1950's.
I have no RPC info to contribute, but I must say I'm enjoying learning from this thread.

Terry

 

[muddstopper]

I'm fortunate for the fact that we've had 3 phase here on the farm since the mid 1950's.
I have no RPC info to contribute, but I must say I'm enjoying learning from this thread.

Terry

:thumbsup:

 

[Mysfyt]

Pretty sure I am not mixing up the starter/pony motor with using another motor to clean up the power. If I am reading right, a pony motor is just a motor used to get the bigger 3phase motor to turning before turning on the single phase power. The pony motor is just used as a starter instead of running a large starter capacitor. The article about running another motor in addition to the rotary is supposed to make the phases more in sync or something. The more motors you are running the cleaner the power. I other words, if you had 3 or 4, 3phase machines running off one
RPC, turning on all the equipment, even though you only plan on using one piece, would make that one
piece you are actually using have a purer 3phase power, Or something along those lines. Of course , I
dont fully understand it. I have only had a couple of days of reading to learn about this stuff. Wait!, a
couple of days of reading makes me a internet expert already. What was it you where needing to
know??:laughing:

Sounds like your getting it, muddstopper! You could literally spend several days researching this subject on Practical Machinist alone. Lots of ways to skin this animal. And if you let the 'magic smoke' out of a motor, you can start a thread on that and get many similar stories from others. I know I have few of my own but sometimes that's how you LEARN and never forget!

 

[LD1]

I think you are getting it spot on so far.

I'll give a quick summary

Static: cheap an no moving parts. A 3 ph motor WILL run on just the two legs of single phase power. But since the legs are 180 degrees out of phase, it won't start and will sit in a locked rotor position unless something else influences it. With a static this is done with capacitors. But you can only operate at 2/3 power since you are only powering 2 legs instead of 2

A rotary is the same principal. It uses a 3phase motor being powered by your 2 hot legs. But that spinning rotor with coppor windings around it induces voltage in the 3rd leg to make 3 phase. Similar to the way an alternator or generator work. How the rotary is started can very. Others have mentioned the popular methods, a rope, a 110v pony motor, or capacitors( basically a static powering a donor motor).

With a rotary though, that 3rd created leg isn't quite the same as the two legs you are feeding power to. Thus some play with different size run capacitors to try to balance the voltages and phase separation better. This is where the more motors running the better the power. But with a rotary, you are still bound by the 2/3 power rule UNLESS you upsize the donor motor. It takes a 15hp donor to run a true 10hp phase convertor.

Actually buying a good quality rotary, it is more than just a donor motor. The 3rd (created) leg they put more windings in the donor to better balance the power from the start. And with a factory built rotary, there is no 2/3 rule. They just change the way they rate them. So if it says 10hp on the nameplate, that's what you can power. Cause they built it as a 15 hp motor, but labeled it for what it can power.

Vfd's are the best solution if you can afford them. They convert the single phase power to DC first. Then convert back to 3 equally balanced AC lines with darn near perfect voltages and phase separation. And they CAN be used on different motors, but NOT more than one at a time. I have a plug on the vfd. I can unplug one motor, plug another in and go. If the specs (hp, fla, rpm, etc) are different, you may have to spend 2 minutes changing a few parameters. But you have so much more control. Not just over the speed. But acxel and decell times, over current protection, over and under voltage protection etc.

Just remember though, with any of these convertors, you need to be sure your equipment cannbe wited to low voltage 3phase. If you have motors that only have high voltage windings, you are gonna be into alot more money for a transformer.

 

[george md]

mudstopper,
I have read the complete thread , a few things to add. If your small motors are single phase , then a VFD would
be a good thing. If more than one is 3 ph then a rotary would work well, or a static unit large enough to run the
mill and a 'slave' motor to give you instant start and instant reverse.

I have run my shop on a non solid state static with a 5 hp slave for 35 +years . The BS from the sales rep that the
motors won't stand up is wrong . The motors that I have used for slave are newer than anything on the machines,
the only failures were the slaves (2 in 35+years) one of which was caused by bearing failure ,the other didn't start
after a power outage. Most of these are old machines - a 1905 -30inch Leblonde lathe (10 hp), lucas #41 3 inch
horizontal boring mill (7.5 hp ) , 26 in lathe early 1900's - 7.5 hp , early 1900's -20 inch american 5 hp , a # 3 horiz
with 3 hp 1920's , 5 ft Cincinnati planer - 1.5-hp , 14 x 48 landis universal cylindrical grinder -5 hp plus small motors,
2 medium vertical mills , old cincinatti #2 horiz mill -1 hp , 14 in lodge & shipply lathe -1hp , and several hoists on bridge cranes . Also about to move in 2 surface grinders and an Index 1.5 vert mill.

Questions call me , # is on web site

george