Rotary Phase Converter

Merry Christmas

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
UPDATE
I went back by the customer and he had the RPC out where I could get to it and also found the wiring diagram sent by the builder of the RPC. As I said before, I have hooked up some that were already sized and all I did was make connections but I don't know a lot about them. From the ones that I hooked up and from the description of the one I was going to order, this one is not like those. The ones I saw had the single phase lines run into the RPC cabinet, the the mfg leg was picked up from there and out to the load along with the single phase lines. So basically the single phase fed through the cabinet and back out.

This one, the way it looks and according to the diagram, the single phase lines enters the RPC cabinet and feeds the RPC motor, but only sends out the mfg leg. The single ph lines for the RPC are to be from a 2-pole 100A breaker, then the single ph load lines are fed from another 2-pole 100A breaker. So the load received 2 conductors from the power source and the 3rd (mfg) leg comes from the RPC. They show feeding a 3Ø panel 1st, then feeding the load.

This seems crazy, for one thing since I only need 60A for the load, there will be no other 3Ø loads added, and why does the RPC need a 100A feed and also the load? I don't really want to use two breakers and I don't want to run 100A conductors since wire is so high right now.

Here's what I would like to do:
Feed the RPC with 60A conductors from a 60A breaker
Inside the cabinet, use dual lugs, where one set of conductors could feed the RPC and the other set feed out to the load, along with the mfg leg
This is how the one I wanted to order is set up. Anything wrong with me doing it this way?
Here are pics of the layout of the RPC along with the (hand) drawing that was sent with it.





Sorry, the pics loaded sideways!
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
To meet 300.3(B), I believe the manufactured line should be run back to the panel with the conductors feeding the RPC, through the panel and then out with the feeder to the load. This is because the manufactured line is part of both circuits.

Perhaps you were already going to do this but I just wanted to point out a flaw in the drawing.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
UPDATE
I went back by the customer and he had the RPC out where I could get to it and also found the wiring diagram sent by the builder of the RPC. As I said before, I have hooked up some that were already sized and all I did was make connections but I don't know a lot about them. From the ones that I hooked up and from the description of the one I was going to order, this one is not like those. The ones I saw had the single phase lines run into the RPC cabinet, the the mfg leg was picked up from there and out to the load along with the single phase lines. So basically the single phase fed through the cabinet and back out.

This one, the way it looks and according to the diagram, the single phase lines enters the RPC cabinet and feeds the RPC motor, but only sends out the mfg leg. The single ph lines for the RPC are to be from a 2-pole 100A breaker, then the single ph load lines are fed from another 2-pole 100A breaker. So the load received 2 conductors from the power source and the 3rd (mfg) leg comes from the RPC. They show feeding a 3Ø panel 1st, then feeding the load.

This seems crazy, for one thing since I only need 60A for the load, there will be no other 3Ø loads added, and why does the RPC need a 100A feed and also the load? I don't really want to use two breakers and I don't want to run 100A conductors since wire is so high right now.

Here's what I would like to do:
Feed the RPC with 60A conductors from a 60A breaker
Inside the cabinet, use dual lugs, where one set of conductors could feed the RPC and the other set feed out to the load, along with the mfg leg
This is how the one I wanted to order is set up. Anything wrong with me doing it this way?
Here are pics of the layout of the RPC along with the (hand) drawing that was sent with it.





Sorry, the pics loaded sideways!
It’s not that any loads 120 volts can go to the manufactured phase, it’s phase to phase voltage, the manufactured voltage is much higher than the other legs, so you don’t want your controls fed from that leg.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
To meet 300.3(B), I believe the manufactured line should be run back to the panel with the conductors feeding the RPC, through the panel and then out with the feeder to the load. This is because the manufactured line is part of both circuits.

Perhaps you were already going to do this but I just wanted to point out a flaw in the drawing
Yes, I already caught that and planned on running all the conductors in the same conduit.
It’s not that any loads 120 volts can go to the manufactured phase, it’s phase to phase voltage, the manufactured voltage is much higher than the other legs, so you don’t want your controls fed from that leg.
Yes, I understand that. The drawing is not mine, it's from the mfg of the RPC. Luckily, the equipment doesn't require any line to neutral voltages.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Yes, I already caught that and planned on running all the conductors in the same conduit.

Yes, I understand that. The drawing is not mine, it's from the mfg of the RPC. Luckily, the equipment doesn't require any line to neutral voltages.
Don’t use it for line to line control voltage either. Use only the other two legs.
 
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