Need some help with an air compressor.

Hey all. I am new to the forums and found my way over here through a couple different sites as I was searching for answers. I am reading everything I can find and will continue reading through this forum but I have to get some info and ask a few questions as I do this.

I have a Champion VR-10-12 Compressor. It has a 120 gal tank, with what they are calling a 10HP pump (it is an R30-A), and a Dayton 2N979 10 HP 3 Phase motor in a 215T frame.

The compressor will run on a 7.5 or 10 HP motor. Right now I have to find out if the 10 HP motor is even good.

I only have single phase coming into my property and think that a phase converter might be the best way to go. I was thinking of building or buying a static phase converter and adding an idler onto it.

If I end up using a 7.5 would a 15 HP motor work and with the 10 hp would a 20 hp work or would I have to go larger?

Also, is anyone in or around the Houston, TX area that knows of a scrapyard or recycling center that I could pick some stuff up at?

Welcome, no expert here. I use a 10hp idler(rpc) to start/run my 5 hp Champion compressor on a 50 amp circuit. I also spin up the idler with a pony motor to reduce the starting amps. I'm not using any start/run Caps. A compressor is a hard starting piece of equipment, 2X the running motor hp is a rule of thumb for an idler.

Shawn Ghormley said:

Welcome, no expert here. I use a 10hp idler(rpc) to start/run my 5 hp Champion compressor on a 50 amp circuit. I also spin up the idler with a pony motor to reduce the starting amps. I'm not using any start/run Caps. A compressor is a hard starting piece of equipment, 2X the running motor hp is a rule of thumb for an idler.

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Are you on the Garage Journal board? I am not sure on the name but your avatar picture looks familiar.


So no start/run caps, does that include caps set up even out the voltage across the legs? So with the pony motor you have a switch that is left off and you run up the idler to running speed, and when it gets there (or close) you turn on your power switch to the idler?

There are a few times that I heard double the HP if your starting a compressor but than there are sites where I saw people asking about 10 HP compressors (old Kellogg, IR, Champion, and Quincy pumps) and a few 15 HP compressors and almost everybody is shooting the guy down and telling him to go buy a new consumer grade compressor because it is a lost cause. I am not sure about the 15 HP but from my reading it seems possible with a 10 HP and pretty likely getting a 7.5 HP running.

As far as I know my pump is set up for no load starting, I have never dealt with a compressor this big.

Right now this is the only thing with 3 Phase that I have and I am not sure if I will ever get anything else, but with the price of used 3 phase I could be talked into lathe and mill (don't usually do smilies but this Phase converter stuff could open up a whole new world)

I also read that having the static in front of the rotary gets your output closer to its actual output, Is this true?

Yes I'm on the GJ board. What size service do you have available?

I have 125A, the box was put in about 8 years ago by the previous owner, I am not sure what is actually available to me but I would think that they would have went bigger if it was there for them.

Also, how can I find out how far away the nearest 3 phase run is too my house? I figure I might as well look at all the options I have, although I don't think they would be very willing to run it for little old me piddling around restoring cars.

I am no expert but I have a 5hp Phase-A-Matic static converter running in rotary mode for my lathe and was considering using it for my compressor (5hp Kellogg) but because compressors are hard start loads, it would need a bigger idler. Phase-A-Matic's website has a listing of sizes and types of equipment that can be started/run with a corresponding size converter. I am not affiliated with them at all, just satisfied that they took the time to talk to me about proper sizing. It was pure luck that I found a used converter at a garage sale by my house and I called them up for a manual. Their static converters can be converted to rotary at any time.

Dave

Static Phase Converter Information Page - Phase-A-Matic, Inc.

DKA65 said:

I have 125A, the box was put in about 8 years ago by the previous owner, I am not sure what is actually available to me but I would think that they would have went bigger if it was there for them.

Also, how can I find out how far away the nearest 3 phase run is too my house? I figure I might as well look at all the options I have, although I don't think they would be very willing to run it for little old me piddling around restoring cars.

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Look for a power line pole that has three transformers grouped together. I don't think this is a viable option for most people $$$$$$.

call ur power company and ask them! quotes are free! they will tell u what options they have for you.

What I would do is get a 7.5 hp motor 1 phase 1800+-
And a smaller pulley for the motor.
This would cost you the least. You might be able to us the magnetic starter with some rewiring.

Andrew
the compressor guy

Thanks for the info guys. NewMexicoairman, for the price of 7.5 1 phase motors I think I could put together a phase converter, or maybe it would cost a bit more but that I would be able to get some other 3 phase equipment to run as well. Also, the 7.5 hp motors I have seen are all high rpm motors....I might not be looking hard enough though.

What is the difference between a 1 phase and 3 phase starter? I was just imagining some wires would need to be switched around and that is all.

I saw this website and was wondering what any of you thought. Does it look like a good setup? 20 hp with pony

2 transformers...

Actually, you don't hafta have three pigs on a pole to get three-phase... oftentimes, the utility company will connect up 'open delta', which only requires two transformers...

I'd suggest you pop open the utility panel, and make sure the feeder to that panel is adequately sized for the panel's actual rating... oftentimes, a garage our outbuilding subpanel will be rated high, but the wiring will be lower, as should be the main panel's breaker... and it's done because the panelboard has lots of breaker spaces, and is more economical than buying a special panel.

The biggest concern I'd have, is that the amount of surge current on startup will be high enough to put hurt to the panel. Starting an RPC is pretty painful to a panel... as is starting the compressor. IF the panel's wiring can handle the FLA of the motor, and it's the only three-phase machine you have, I'd say go with the single-phase motor and smaller drive pulley. You'll lose a little CFM, but it'll still be a useful machine.

If you want full capacity, though... and have enough power at the panel to run the motor to full capacity, but not quite the starting power... you could use a VFD to convert single to three phase, and then 'ramp' it up slow to cut down on inrush current... and then run a smaller sheave to increase leverage, and then overspeed the motor a bit to get the proper compressor speed... and finally... put a delay on the unloader valve (solenoid valve and a timer relay, or use an auxiliary output of the VFD to operate it, so that the motor gets up to speed before the compressor gets head pressure... and you should be able to get full-snot performance without beating up the power panel.

Added benefit here, is that if you need air, but not incredible volume, you could slow down the motor to BELOW base speed a bit, get good performance, fewer starts, and a fair amount quieter performance for the partial-demand scenarios.

DaveKamp, WOW!!!! thanks for the reply, I am still trying to digest that explanation for running it full capacity.
I'll start with just a few things.
I forgot to mention that the Garage is detached....I am guessing you can call it detached, the front corner is about 20 feet from the back of my house but has a covered walk way (I think they used to call L's a long time ago), that attaches the house and garage. there is an access panel so you can run conduit and wires to the garage and right now there is only a run with 12-3 romex from the main panel to the garage for a couple outlets and lights.....there is no sub panel for the garage.

A friend is going to be helping me run conduit and wire from the main panel through my attic, through the covered walk, and too the garage where we are going to install a new box for 120v and 240v.

Also, when looking for a VFD if I have a 10 hp motor I want to run would I be looking for a 10 hp VFD or would I want something rated higher like a rotary phase convertor.

Good info...

Good info.

12-3 romex won't carry much... that's basically two 30A feeders, and I really wouldn't push it that hard, with the romex being in conduit...

Hopefully, the conduit is big enough for you to pull through THREE copper wires of say... #6awg (a 60A panel) or even #4 (80A panel)... and then also pull through a #8 green wire (ground). Use stranded, lest it will not pull.

Put a 60A (for #6) or 80A (#4) breaker at your main panel. At that point, you should have more'n enough power to start that compressor.

IF you go the VFD route, remember that you'll be asking it not only to control motor speed, but to do it with just single-phase input. Many VFDs WILL allow single-phase input, and some of 'em will actually have ratings at single-phase in... best to do research on the model and brand which you're looking... and if you find no ratings, to increase the VFD size by 30-50%. For a 10hp motor, I'd go with a 15hp VFD. I'm curious as to what you're running, that requires that much air-superiority in a garage... perhaps expecting more like 5-7hp of compressor load would be more appropriate. I have a 4-cylinder 15hp compressor, and I run it from a 5hp 440 motor, an Allen-Bradley 1336S drive, and get my 480v single-phase by running an ordinary 3.5kva transformer 'backwards'... feeding 240v to the 'output', and pulling 480 off the 'input'... I overspeed the motor (2500rpm or so for an 1800rpm motor) and can ramp it up quick enough so that I don't even hafta mess with the unloader. When it kicks on, I don't even see the lights dim.

I will definitely have enough space to run any wire I need, The Romex is what the previous owner did and the conduit is what I put in. I also did not use any 90 degree (as far as I recall) and where it enters the garage it is not finished.....I figured that when I got to running wire it might be easier putting the last few pieces on after the wire was to the garage. We are in the process of remodeling so I am hanging all new sheetrock, mainly because I am re-insulating the walls including the inner walls for sound barrier reasons, running new Romex because the house is partial Aluminum wired (the previous owner started the change over), and we are wiring the house for audio, and video with everything meeting in a central closet. I know it really does not have to do with the garage and air compressors, it is really just to show that right now we can do pretty much what we want as long as the lines coming into the house can handle it.

DaveKamp said:

Good info.

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Yeah, It would have been great to mention that all in the first place, I'll have to admit to being confused that day.

DaveKamp said:

I'm curious as to what you're running, that requires that much air-superiority in a garage...perhaps expecting more like 5-7hp

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I had actually down graded my search for a local compressor a few times....I went from looking for an older 5-7hp range that loped along at a nice slow rpm, to finding something of the same hp range but newer that ran at a fairly slow RPM, and then figured that I might as well buy something new that ran in the 3,000 plus RPM band and make it last as long as I could.....then this compressor came along and it was all over, This one is the one that I was hoping for but figured I would never get so why bother looking.

Right now I have 2 cars that I need to restore, 3 I am including my CJ-7, I might very well sell one or two of these and getting one or two more to restore, and who knows if I will stop after that. I am only 34 but my Wife and I are planning to stay in this house for the long haul which means I finally get to have the garage with the resources I have always wanted without having to compromise (too much at least) and that means that I can finally run a decent media blasting setup, get into some soda blasting, paint equipment, and be able to run almost any air tool I can think of without much (or any) trouble.
Honestly this compressor is overkill, but what use is life if you can't do something completely crazy and un-needed?

Champion does sell this pump with a 7.5hp motor and I would be perfectly happy with that, I would probably be happy with what a 5hp would get out of it. My only issue is that people had brought up that oiling might be an issue with a 5hp.....and you are mentioning running a 5hp faster, are you running the pump faster or keeping it at a lower RPM?

What transformer are you using? do you have a part number? also, I have a couple links to eBay auctions from when I searched for an Allen-Bradley 1336S. Are these of the same type you are running?
Allen-Bradley 1336
ALLEN-BRADLEY
1336S-BRF30-AA-EN4-1336-L6-Allen-Bradley-B-163

There are a bunch on there with starting bids from a couple of dollars all the way to "buy it now" for over a thousand.

Also, What compressor are you running?