Another Rotary Phase Converter

JimDawson

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I'm getting ready to build a RCP to power up my new (to me) CNC lathe. All this is going to power up is the axis drives and spindle, the three small 3 phase motors for the coolant pumps and the hydraulics will be powered by VFDs from a separate feed, as will the computer and controls.

I have a 15HP compressor motor to use as the idler. 2 pole, 3450 RPM, 240 volt. I tried to remove the motor from the compressor head, but it turns out that the armature shaft and the screw are one piece. So I pulled out the mating screw, greased the bearings and put the housing back together.
1508285305044.png

Here is the schematic of the RPC. Comments are solicited and welcome. Starting is with the 3/4 HP, 3450 RPM, single phase pony motor to minimize the start load on my electrical system.

1508284601028.png
 
Wow. New format here look smooth. Me like!
JD, how does the pony motor help? Never heard the term or seen a schemo with one. Does it just stay running?
 
All it does is spin the idler motor up to speed before it's energized. That way there is very little start load. Once up to speed, the switch will thrown to the RUN position momentary which will then pull in the main power contactor. That will take the pony motor out of the circuit, but it will still be mechanically driven by the idler motor.
 
Cool. Just took a spin on this thread. http://www.paragoncode.com/shop/rotary_converter/

My next one will be the same too. My only note is to select the best caps you can on the budget. At my aerospace place long long ago.... Caps would go esr bad until we started spec'ing the 105c or higher rating and the new needed to use quality mfr lines. Just a thought.

Peace and may the wild leg be happy and joyous--- ha.... Long day if I am typing junk like that. :-(
 
I'm getting ready to build a RCP to power up my new (to me) CNC lathe. All this is going to power up is the axis drives and spindle, the three small 3 phase motors for the coolant pumps and the hydraulics will be powered by VFDs from a separate feed, as will the computer and controls.

I have a 15HP compressor motor to use as the idler. 2 pole, 3450 RPM, 240 volt. I tried to remove the motor from the compressor head, but it turns out that the armature shaft and the screw are one piece. So I pulled out the mating screw, greased the bearings and put the housing back together.
View attachment 244517

Here is the schematic of the RPC. Comments are solicited and welcome. Starting is with the 3/4 HP, 3450 RPM, single phase pony motor to minimize the start load on my electrical system.

View attachment 244512

15 Hp seems like a big motor to operate with only two legs - especially considering the light loading. Your schematic shows three L-L receptacle banks, but no single three-phase takeoff to supply a 3-phase load.
 
15 Hp seems like a big motor to operate with only two legs - especially considering the light loading. Your schematic shows three L-L receptacle banks, but no single three-phase takeoff to supply a 3-phase load.

3 phase output is on the right side; U, V, W. Not so lightly loaded, about 12.5 KW at max load. The spindle motor is 7.5 KW + the 1.5 KW live tooling drive.
 
ok - so you are driving a ~10 hp motor --so you do have that 15hp motor well loaded - maybe too much given that it is operating on only two legs. May want to watch heat and what your waveform looks like, etc.
 
15 Hp seems like a big motor to operate with only two legs - especially considering the light loading. Your schematic shows three L-L receptacle banks, but no single three-phase takeoff to supply a 3-phase load.

I believe those are capacitor banks for voltage correction, not receptacles and he does show 3 phase output at the right side of the schematic.

Ted

Well Jim, I guess we were typing at the same time !
 
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