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  #11  
Old 10-11-2020, 12:12 AM
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Originally Posted by 460 Delta View Post
The tag should have the voltage XXX out, but many motor shops don't do that. If it's a 3 lead, most likely it's for 460 now, especially if the leads are 14awg.
Leads are bigger then 14 awg. If it doesn't work out I can return it.
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  #12  
Old 10-11-2020, 06:06 AM
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Originally Posted by OldRedFord View Post
Leads are bigger then 14 awg. If it doesn't work out I can return it.
Do you have a place nearby with real 3 phase power to test it on? If you do, and it's 208 or 230, power it up and see how fast it comes to speed. If it comes up to speed instantly, it's a 230 motor. If it's slightly sluggish, it's a 460 motor. The only real problem is if it's been made into a straight 200 volt motor, it will run on 230, but will be magnetically saturated and will run very hot.
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  #13  
Old 10-11-2020, 10:29 AM
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Originally Posted by 460 Delta View Post
Yeah a lighting contactor will work, but you ought to have a overload relay on it. I've seen many that didn't have them though.
A lighting contactor will never have a O/L relay as they are for lighting loads & no need for them, unlike motor loads. Technically a lighting contactor cannot be used for motor loads as they are rated & listed for tungsten, & ballast, loads, not motor loads, but doubt there is much difference internally or electrically, other then the coil could be 277V.
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  #14  
Old 10-11-2020, 11:01 AM
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Originally Posted by Norcal View Post
A lighting contactor will never have a O/L relay as they are for lighting loads & no need for them, unlike motor loads. Technically a lighting contactor cannot be used for motor loads as they are rated & listed for tungsten, & ballast, loads, not motor loads, but doubt there is much difference internally or electrically, other then the coil could be 277V.
I never meant that lighting contactors have O/L's on them, but re-reading my post, yeah I wasn't that clear. I mean a RPC should have O/L's on them, but I've seen numerous ones, store bought and homebrew that didn't.
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Old 10-12-2020, 09:32 PM
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I've got two 227 microfarad capacitors for starting.

Im not good at reading schematics but I've seen pictures if others builds and some the capacitors just have one wire going from one to the next, others two wires going between each cap.

Anywho I'm only getting 120v out of my two caps. Seems to not be enough to spin up the 10 to idler. But im makimg progress.

Not really following any schematics. Just using the little control smarts I have.


The process for my rpc is as follows

220v single phase to some screw terminals.

220v single phase to a 220/120 control transformer.

120v from the transformer to a on/off switch.

When the switch is turned on....a timing relay closes for a few seconds and closes a Allen Bradley 700 type P relay. This sends power through the start caps...rhe start caps go to the 3rd leg on the contactor. When the timer times out the relay opens removing the start caps from the circuit. The other two legs on the contactor have 220v single phase applied.

The motor tries to spin up but I don't think I have enough start capacitors.

For right now im usimg the lighting contactor and 30 amp slow blow fuses on the motor side. It has a 120v coil. The whole unit plugs into a 50 amp outlet.
Going to try to pony start the idler next and go from there.
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  #16  
Old 10-13-2020, 04:03 AM
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You are gonna need a few hundred more uf than what you have there to get it to self start. The electrolytic style are pretty cheap and most any decent electrical SH.
After it's up and running is when the trial and error starts, you'll need to put oil filled caps in line to bring up the run voltage and help shift the phase for a smoother run.
You'll end up likely with a different uf amount on AC and BC but that's fine, as long as the voltage is close to the same.
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  #17  
Old 10-13-2020, 12:32 PM
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I had to look at mine, I have a 440 uF cap on my 7.5 hp motor. It is not real picky. figure 60 to 80 uF per horsepower to get it kicked over, anything over 1 second on my setup and the system does not like it, weird noises a plenty over 1 second.

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  #18  
Old 10-14-2020, 05:43 AM
bunkclimber bunkclimber is offline
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Default 10hp phase converter

having built many of these, here is a recipe I use that works well..20mfd per HP on the run side, 100mfd per HP on the start side. Use only 330V rated start caps, and 440v rated metal can run caps.Your start contactor is the heart of the converter, use a 60amp or greater contactor for best reliability,I see you have that already. Use a 12"x12"x6"deep or better electrical pull box to house it all, it gives you plenty of room to lay out the contactors,caps and terminal block; it makes it easier later to work on it if you have to. All power side wiring from caps to terminal block should be #12 for minimal voltage drop. I have used RTV Silicone and (zip ties/Ty-Wraps/wire ties) to hold the caps together into a module block, it works well and isn't that hard to cut apart to replace a cap; its pretty rare to have to do that if you use the 440v rated caps. Most of the caps have 1/4"slip-on terminals, if you use crimp-on style wire terminals get good quality nylon insulated ones,not the cheap chinese junk offered on ebay..nothing but problems with that crap.The loose tolerances in the imported terminals don't make for good connections even when you crimp down hard on them. Anyway only use a 230/440/460v 1725rpm (4-pole) rotor motor, a 2pole 3450 takes longer to wind up.Don't use wire nuts to make connections,they work loose,look like shit and cause loose connections. One of these I built 25yrs ago for a customer is still chunkin' away,no issues yet. FWIW
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Last edited by bunkclimber; 10-14-2020 at 05:50 AM.
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  #19  
Old 10-14-2020, 06:14 AM
bunkclimber bunkclimber is offline
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Default 10hp rotary phase converter

Good place to purchase run and start Caps for converters: some 80mfd runs for example:

https://surpluscityliquidators.com/p...hz.html?195869
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  #20  
Old 10-14-2020, 01:51 PM
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Quote:
Originally Posted by bunkclimber View Post
Use only 330V rated start caps, and 440v rated metal can run caps. FWIW
at 240 volts AC the peak voltage is about 340 volts, cap like to charge up to peak voltages.
I would advise no less than 440 volt rated capacitors.

over the years manufactures have confused the voltage ratings
originally voltage ratings are maximum break down ratings.

I noticed some import motor capacitors seem to go by operating "RMS" voltage.
best to go with higher rated caps when unknown.
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