7.5hp r7 RPC, 3 phase panel, disconnects, starters. need some advice

keith524 · Sep 21, 2014

im new to the 3 phase ordeal, and would like alittle advice on how to go about what I need to do. I got my baldor 3-phase grinder hooked up with your guys help, now for the bigger project. the whole shebang!
I have acquired

phase-a-matic R-7 7.5 hp RPC
square d 200 amp 3-phase panel, this thing is a monster! with some breakers
2 fused disconnects, both 30 amp disconnects
2 magnetic starters, one nema size 1 square D starter with thermal overload, the other Gould a.c. mag starter class a-20 starter
some metal flex conduit
20ft piece 6-4 flexiable wire
3 male, 2 female 3phase twist lock plugs
4 non fused square d disconnects

im at the point where im ready to hook it up, the 3 phase panel has 30 spaces. I was thinking maby I could run everything from the 1 panel since it was so damn big but I want to make sure to have plenty of room in the future. right now, I have

2 cincinatti hydra shifts, only keeping 1 3 phase lathe
1 national gap bed 14x40 lathe 3 phase of course
1 Bridgeport j head
1 index mill

I only plan on keeping 1 3-phase lathe and 1 3-phase mill.

any reccomendations? as far as keeping the single phase panel, going from RPC to square D starter then to 3-phase panel then to disconnects? any help would be great!

keith524 · Sep 22, 2014

here are a couple pictures.

sealark37 · Sep 22, 2014

I am no electrician, but my system goes: single-phase breaker to RPC cut-off, RPC to 3-phase panel, panel to individual disconnects, then to starters. Regards, Clark

keith524 · Sep 23, 2014

wonderful clark, that's a start for me, thank you for that, that is exactly what I was wanting to know. all of my 3 phase machines should have motor starters on them, that's another reason I was asking about these thermal overload contacts.

keith524 · Sep 26, 2014

ok one more question, the 3 phase panel I bought off cl is way bigger than I thought it was. Should I run 220 single phase out to one of the thermal overload starters and use the breaker to turn it on/off. or from 220 single phase to RPC then the 3 phase panel?

moonlight machine · Sep 26, 2014

220 1PH to rpc then to 3PH panel, Breakers to each machine. Why do you think your panel is so big? My SQ-D 3 PH panel has 42 spaces and does not seem so big to me.

Vladymere gr · Sep 26, 2014

keith524,

I have attached a photo of my setup.

What you want is a 208/230 single phase circuit from a twin pole circuit breaker running to a disconnect switch. The disconnect switch goes to your your RPC. The output of your RPC will go to the main buss bars of your three phase circuit panel. You 30 slot three phase circuit pannel is good for 10 three phase circuits. You will feed each three phase device from a three phase breaker into a magnetic motor starter. From the motor starter you feed the motor on your three phase machine.

Below is a photo of my RPC set up. On the left side of the wall is my single phase circuit breaker panel. The conduit running below the window (with the ugly curtain) is the feed to the RPC/three phase system disconnect switch. The disconnect switch feeds my RPC. The RPC feeds the three phase circuit breaker panel which I have located above the RPC box. Below the RPC box, on the floor, you can see my idler motor.

I have two three phase lathes, a three phase Bridgeport mill and a three phase twin post auto lift. Each of these devices has a seperate three phase circuit breaker and they each have their own magnetic motor starter.

Circuit breakers protect your wiring, magnetic motor controls protect your motors.

Good luck with your setup,

Vlad

keith524 · Sep 30, 2014

what size wire did you use from the panel to the machines? I found some 8 guage that is a decent price.

Vladymere gr · Sep 30, 2014

keith524,

My Bridgeport mill, South Bend Lathe and Cincinnati lathe are alle two hp or less. I am using 15 amp breakers, the smallest three phase I could economically purchase. 15 amp breakers require 12 gauge wire. My twin post auto lift has a 26 amp max load so I am running 10 gauge wire.

Three phase circuit breakers can be a bit pricey. Look on line for recycled, recertified breakers. These can be had for a lot less.

Vlad

Vladymere gr · Oct 2, 2014

keith524,

I stated that 15 amp breakers are the smallest three phase breakers I could economicallly purchase. With a 15 amp breaker 14 gauge wire can be used. I used 12 gauge as I had receive a bunch of it, cut inot a variety of lengths, free.

Three phase breakers smaller than 15 amp are available but tend to be about $100 to $125 new.

Vlad

keith524 · Oct 3, 2014

I guess I just wasn't expecting the panel to be as tall as I am! it just seems like it has a lot of extra room in it. I just wasn't expecting it to be that big.

vladymere, thanks for the input. I have plenty of 12 gauge wire, I just assumed I would need 8 or 10. I think I got it from here fellas, thanks for the help once again!

Vladymere gr · Oct 3, 2014

keith524,

From the single phase panel to the RPC I am using 6 gauge wire for my 5 hp idler. From the idler to the three phase panel buss bars I am using 8 gauge wire. Again this wire was free salvaged wire.

Vlad

keith524 · Oct 19, 2014

ok guys, I think I got er done! I flipped the disconnect and I measured the voltage from each leg, im getting,
124V on A
244V on B wild leg
124V on C

is that good? am I ready to run some power to my machines?

peterh5322 · Oct 19, 2014

You MUST be measuring using the neutral as a reference in order to get the first and third values.

If the manufactured leg was working properly you should see about 215 volts as the second value, but you are seeing 244, which would normally indicate capacitors too large or an unloaded condition.

keith524 · Oct 19, 2014

I don't have it hooked up to a machine yet, that's just the RPC turned on by the disconnect switch, im getting the readings from the 3 phase panel on labels A,B,C. I don't even have the 3 phase panel flipped on yet. so the readings should be taken while a machine is hooked up? im new to this, im using the phase a matic R-7 7.5 hp RPC.
if I measure from A-B 263, A-C 246 B-C 281

I was measureing from the ground to A, ground to B ground to C

peterh5322 · Oct 19, 2014

"if I measure from A-B 263, A-C 246 B-C 281"

Then, A-C is high, but well within reason. Here at my site I am reading 256 most of the time.

A-B of 263 and B-C of 281 indicate either: 1) unloaded, or 2) capacitors too large.

"I was measureing from the ground to A, ground to B ground to C"

Which was as I suspected.

keith524 · Oct 19, 2014

ok Peter, so I should be good then correct? this is a phase-a-matic premanufactured unit, and yes I am headed to menards to get some conduit to run over to my machines today!

peterh5322 · Oct 20, 2014

I think you'll be OK after you put a load on it.

But just to make sure, check A-C, A-B and B-C with various loads.

keith524 · Oct 20, 2014

ok peter, thank you for the quick response, one more question, can I use this cord and box for a quick temp for now? I don't know what it is, RV cord I believe. its huge. anyways I just wanted to check everything, and wire the mill up with this extension cord to make sure I got everything is right. also, I have 2 hydrashifts to hook up, one has a fuse block missing inside the electrical box. I don't think it ever had one in it. doesn't look that way anyways. should I fool with trying to find one to fit in there and wire it up like the other one? they came out of the assembly line one after the other. serial numers are 000000190 and 000000191

7.5hp r7 RPC, 3 phase panel, disconnects, starters. need some advice

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