50 hp Motor wiring qoestion.

m-lud · Jan 16, 2021

I got this 50 hp motor with an 20hp Kellogg's air compresso I boughtr to make a RPC. I would have had it running 3 years ago but I expected to swap some wires to make it 220. The Three wires stopped me.
How do I confirm what this motor is wired for? Olms check?
I can pull the end bell off but would prefer not to.

I have a 20 hp Pacemaker lathe coming home soon so there is an urgency is to use it as an idler for a RPC
I thought the motor was new when I got it but now think its been refurbished at a motor shop. It was pristine when I got it.
Notice one tag is riveted over the top of another.

I need to confirm its voltage. 240 0r 480

Any advice appreciated
.Mike
.

TDegenhart · Jan 16, 2021

Two ways that I can think of. Take it to a motor shop and let them tell what it is. Connect it to 230 and observe and measure currents. If it is 230, it will be quite happy. If it is 460 then it will be sluggish and currents will be low.

Tom

m-lud · Jan 16, 2021

I cleaned the tag and got a little better picture.
In the right it says [ Suitable for part winding start on low voltage ] ??

Toms Wheels · Jan 16, 2021

You need to chase the 3 wires outside the motor housing. where then connect to the the windings, look for the numbers on the wires.
Write Leg 1 is connected to XX wires, Leg 2 is connected to YY wires. Then look at the schematic on the motor plate, match up the numbers will show high or low voltage.

m-lud · Jan 16, 2021

TDegenhart said:
Two ways that I can think of. Take it to a motor shop and let them tell what it is. Connect it to 230 and observe and measure currents. If it is 230, it will be quite happy. If it is 460 then it will be sluggish and currents will be low.

Tom

Ya I have seen 480 motors hooked to 240 and dragging
The 50 hp makes me nervous. Ill have to give it a shot. I was hoping for a way to use a meter checking resistance but that wont ID the voltage.
It turns smooth. Good Idle motor for RPC if its good.

m-lud · Jan 16, 2021

Toms Wheels said:
You need to chase the 3 wires outside the motor housing. where then connect to the the windings, look for the numbers on the wires.
Write Leg 1 is connected to XX wires, Leg 2 is connected to YY wires. Then look at the schematic on the motor plate, match up the numbers will show high or low voltage.

I will have to pull the end bell then. Not a big deal to do that.

m-lud · Jan 16, 2021

View attachment 310746 View attachment 310747

The three big wires appear to be tied right into the windings with shelack on the ties. Will the 9 wires still be in there? If so that's good. I understand the schematic wiring.

m-lud · Jan 16, 2021

I think Ill take TDegenhart's advice for starts. I got a better look and can see the 10 or 12 gauge wires bundled in with the large gauge wire. I dont see any tagged wires. They have been bundled and tied to the windings for as long as the windings have been shellacked.
A coupler has to come off before I can slide the end bell off the rest of the way.. Its soaking with penetrating oil.

m-lud · Jan 16, 2021

The wires are bundled where the oarnge cover is

the beartng is about 4.5" diametre with half hardened greas so they need flushed out

another bundle from a line

armerature anf the field plates need cleaned

The mice got in it.

Weather its 480 or 240 the tag is wrong.,
Ill clean and reassemble and hope its 240.

Phil in Montana · Jan 16, 2021

It makes no diff you cant run the motor, you most likely don't have a 400 amp service, why is bigger always better...Phil

m-lud · Jan 16, 2021

Phil in Montana said:
It makes no diff you cant run the motor, you most likely don't have a 400 amp service, why is bigger always better...Phil

Bigger is not always better. It came with an air compressor that I boought. Trying to use what I have..
The post today was to Identify the voltage. Its most likely not going to work for me.
I intended to put this in the RPC forum.
The tag didnt jive with the three wires. Its been rewired in a motor shop.

Need an Rpc big enough to run a 20hp lathe

Phil in Montana · Jan 16, 2021

It would be very doubtful that the motor is anything but 480, a 50hp 240 volt wold draw 130 amps on run and over 700 amps on start up a really big deal. Now if you can get by with a 12 1/2 hp motor feed the 50hp 240 volt and have the motor hooked 480...Phil

texasgeartrain · Jan 16, 2021

Usually if a two voltage capable motor was rewired for a single voltage, they might change the tag. Doesn't mean it was re-wired for either high or low exclusive, but possible.

If that motor checks out, and can be set for low voltage, I'd set up a pony motor to get it spinning before hitting the start button though, to cut amp draw at start up.

An outfit I used for my rpc control box I like is North American, and was surprised to see they actually do have a 50hp !

A bit pricey at about $800:
CP-50: 50-HP Rotary Phase Converter Control Panel | NAPCco

Couldn't find pics inside the 50hp, but looking in the 40hp its capacitor madness !

Rotary Phase Converter PL-40 Pro-Line 40HP - Built-In Starter, Made In USA | eBay

And here I am slightly nervous prepping for a 20hp rpc.

m-lud · Jan 16, 2021

Quot
It would be very doubtful that the motor is anything but 480, a 50hp 240 volt wold draw 130 amps on run and over 700 amps on start up a really big deal. Now if you can get by with a 12 1/2 hp motor feed the 50hp 240 volt and have the motor hooked 480...Phil

. I'm not following you. :scratchchin:

?? Explain the last sentence

I was considered getting the 50hp rotating about 500rpm's with a belt and 1hp single phase before starting to ease that initial surge but want a clean setup.
\
I'm considering using the 20hp compressor motor for the RPC along with a heavy older 10hp as a second Idler. ..
Cal sorry, I intended to put this on the RPC forum.

Phil in Montana · Jan 16, 2021

Wire the motor for 480 volt,but supply it 240 volt... .5 voltage times .5 the amps = .25 the hp But with lousy power factor but it works. You also have a motor shop bring out all 12 wires and wire the motor 277 volt delta and use it on 240 volt, this would drop the hp to around 30 hp, still with poor power factor. Used motors dont cost all that much and you could find what you want for 2-300 bucks I am sure... I have used all these tricks to get the HP (demand down) so I can run big machines on a smaller supply service...My 72 inch Bullard came with a 100 hp that I would not run on a 400 amp 3 phase service and the demand charge was over $500 every time it ran 15 mins for the month, I ran it on 240 and now had a 25 hp more hp than it ever needed...Phil

m-lud · Jan 16, 2021

texasgunsmith said:
Usually if a two voltage capable motor was rewired for a single voltage, they might change the tag. Doesn't mean it was re-wired for either high or low exclusive, but possible.

If that motor checks out, and can be set for low voltage, I'd set up a pony motor to get it spinning before hitting the start button though, to cut amp draw at start up.

An outfit I used for my rpc control box I like is North American, and was surprised to see they actually do have a 50hp !

A bit pricey at about $800:
CP-50: 50-HP Rotary Phase Converter Control Panel | NAPCco

Couldn't find pics inside the 50hp, but looking in the 40hp its capacitor madness !
Rotary Phase Converter PL-40 Pro-Line 40HP - Built-In Starter, Made In USA | eBay

And here I am slightly nervous prepping for a 20hp rpc.

If the 50 hp is 240 the pony motor is a good option.. I am still going to see what it does.
I have kick started and pushed idler belts on so many 3 ph motors as a kid I would do an idler but better than farmers I've worked for. Scary. You were typing about the pony motor as I was. It works

m-lud · Jan 16, 2021

Phil in Montana said:
Wire the motor for 480 volt,but supply it 240 volt... .5 voltage times .5 the amps = .25 the hp But with lousy power factor but it works. You also have a motor shop bring out all 12 wires and wire the motor 277 volt delta and use it on 240 volt, this would drop the hp to around 30 hp, still with poor power factor. Used motors dont cost all that much and you could find what you want for 2-300 bucks I am sure... I have used all these tricks to get the HP (demand down) so I can run big machines on a smaller supply service...My 72 inch Bullard came with a 100 hp that I would not run on a 400 amp 3 phase service and the demand charge was over $500 every time it ran 15 mins for the month, I ran it on 240 and now had a 25 hp more hp than it ever needed...Phil

I just learned some good stuff.
Thanks

Hillside Fab · Jan 16, 2021

Phil in Montana said:
My 72 inch Bullard came with a 100 hp that I would not run on a 400 amp 3 phase service and the demand charge was over $500 every time it ran 15 mins for the month, I ran it on 240 and now had a 25 hp more hp than it ever needed...Phil

Not necessarily doubting your story, but the way I read the demand charges in my contract doesn't 100% jive with that.

The 15 min part does, so you dont get nailed for your inrush to start the motors, but if the machine will run on 25hp, I dont really see why it would be using enough juice wired on 480V to kick in any crazy demand fees? You're basically just idling that huge motor right?

I have a digital service meter, but even with every motor in the shop idling...which is about 150hp worth of nameplate, I only got about 20kva on the meter... and demand kicks in at over 100kva for 15min continuous IIRC.

I could be completely wrong here, and you might save me a surprise fee? Even with a couple machines running pretty hard I haven't crested 30kva continuous on the meter yet.

Thanks.

Phil in Montana · Jan 16, 2021

For the last 50 years I have had a 800 to 1k demand charge every month, With the power co here in Montana the demand is 13.00/kw so a 100 hp will run unloaded at 25% of fla, the kw would be around 100kw kw X .25 =25kw x 13 bucks=$325.00 plus the usage charge .12x 100 so 12.50 more so total cost to start and run 1 hour unloaded (not doing any work )$337.50 for the first hr just because I pushed the start button. Now if the machine was cutting the price would climb up...I alway charged $500.00 for every job that went in the bullard for the electric bill. I was not cheap to run the big machines, but when I cut the hp to .25% the cost of running the machine went way down. 25 hp was more than good for the gearing the bullard had. At 100 rpm the chuck was fling 72 inch x 3.1416 = 1884 sfpm, most the the time it was ran at 10-40 rpm...Phil

Hillside Fab · Jan 16, 2021

Phil in Montana said:
For the last 50 years I have had a 800 to 1k demand charge every month, With the power co here in Montana the demand is 13.00/kw so a 100 hp will run unloaded at 25% of fla, the kw would be around 100kw kw X .25 =25kw x 13 bucks=$325.00 plus the usage charge .12x 100 so 12.50 more so total cost to start and run 1 hour unloaded (not doing any work )$337.50 for the first hr just because I pushed the start button. Now if the machine was cutting the price would climb up...I alway charged $500.00 for every job that went in the bullard for the electric bill. I was not cheap to run the big machines, but when I cut the hp to .25% the cost of running the machine went way down. 25 hp was more than good for the gearing the bullard had. At 100 rpm the chuck was fling 72 inch x 3.1416 = 1884 sfpm, most the the time it was ran at 10-40 rpm...Phil

Ah. Im still on a small service, so no demand charges. 200amp 480v. I bump into a large service if I exceed the 15 min rule, or a monthly rule...i think the monthly rule is maybe equiv to a $1000 bill, Id have to look again.

50 hp Motor wiring qoestion.

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