Please please help with a switch issue hooking up my 3 phase

A balanced RPC isn't cheap so I am making sure I buy all the proper parts to hook this up to get maximum efficiency and life. .


to the contrary,
a balanced rpc can be achieved by adding a couple of Run Capacitors between phases.
i recently balanced a 7.5 hp RPC for less than $35 in capacitors. it really doesn't get much cheaper.

for reference, a 5 hp RPC can be made more efficient by adding an 80uf run cap between the generated leg and 1 hot leg.
then add a 60uf run cap between the 2 hot legs , you'll see the voltage will be within 10% between legs loaded.
10% is considered balanced.[/QUOTE]

Well considering I didn't build it . It cost me $450 which is a pretty good deal but still a good chunk of change so I don't want to screw it up. I just met with the owner and builder today and he explained about how all the parts work . The motor starter in the unit is to allow the starter caps to be on and then cut off and it is controlled with the relays . And like you said the run capacitors help to balance the power . So it was pretty interesting to learn about it all! The time delay switch in there is for the start caps as well.

I returned the momentary switch because I really didn't need it or the extra cost of buying contractors and heaters . I guess I could have done some salvage finds but really I just needed the disconnect . I bought a knife type disconnect which was fusible and put the 20amp fusetronic time delay fuses in it and I will control the RPC with that. Maybe one day I will try my hand at building a RPC for the fun of it. I will need another one in the larger shop I'm building behind my garage . I really learned a lot In the past night! Thank you guys for helping me out. I will post photos after I get it all hooked up . I'm building the frame to mount the motor on the wall tonight or tomorrow .
 
Did anyone think about using a compressor relay found in the outside portion of a central air conditioner? You can use 1 pole of the relay for 120V and both for 220V. The coil that controls the relay is usually 12 or 24 volts. You can use a toggle switch and a small 110V to 24 volt transformer to apply current that will energize the relay coil. This in turn will pull up the relay. You can get a small transformer for under $10 and switch under $5. Connect the neutral and hot wire to a cord set to plug in and the other side to the input side of the transformer (110V) using a switch on the hot side. Connect motor leads to common and side of relay. When energized, the coil will pull in the relay as long as the switch is in the on position, thus pulling the relay in and connecting the motor. When the 24 volt coil is turned off, the relay drops out isolating the motor. Hope this helps!
 
Back to reply #19

I misread somewhere, but when you said about my freinds setup >>I now got it (problem). Back to the
static,, Mine runs fine with all four motors at the same time. But I have to first start the main motor,
seems that acts as a generator for the other three, once all are running I can shut down the main
and the others keep running. Example other day -start main-start coolant pump-shut off main and
I sucked coolant out in a pail (im changing the coolant to new) All I can say it took awhile but the
pump ran and ran didnt even get warm, so I dont know, but it works fine. sam
 
Just saw your post. You probably have it figured out by now, but here's my two cents. I have a 5 hp rotary phase converter and was faced with a similar problem. Converter came with a knife disconnect switch and a drum switch attached to start the converter. Had to rotate drum switch then engage knife switch. Big pain and lousy engineering. I use a Cutler Hammer on/off monetary switch remotely in my chip equipment room 25 feet away. Ran 5 wires to it from a magnetic contactor, which controlled current to the disconnect box which is always on, through the fuses and on to the converter. Really simple and been working for the last 8 years with no problems. I don't think the drum switch is even connected now. If you need any info in detail, I could take some pictures and forward or attempt to post here. I have a 5 connection mag contactor, while you have a 4 connection. I can't remember if I used all five, but believe I carried 2 wires down to the disconnect box. I'll have to look to be sure. Been a long time since I wired it up.
 
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