Compressor 230v with 115v plug?

[kredden]

I recently picked up a free Craftsman 4HP compressor which I was told was working fine and it runs for about a minute before bogging down to a standstill and then trips the thermal switch on the motor. The guy I got it from said he never actually used it but the neighbor who gave it to him used it all the time with no issues.

I've been doing tons of searching around and ruled out the switch. I thought maybe it was the run cap so for a $9 gamble I replaced that and it still did the same thing. Bought a new multimeter (been needing one anyway) that has capacitance testing capability and tested both run caps and the start cap and all were within spec.

The motor hums along fine without the belt attached or if I keep the pressure valve open. With the belt attached it will build pressure to about 40 PSI and then bog down and trip the thermal if I let it bog for too long. This is running on a 115v 20A circuit.

What has always bothered me is the motor plate only says 230v on it not 115/230. Had a thought tonight and popped the motor access plate off and I think what I'm seeing is indeed a motor that is only supposed to do 230v correct? There are not 4 spades to move the wires around on, just the two for black and white and the green. One thing I did notice is that one of the previous owners put a new power cord on it as it is a Husky one and there is electrical tape around the spades in the switch.

Am I missing something or did one of the previous owners just replace the plug with the wrong type (115v) and this should be a 230?

 

[johnre]

I'd say you are correct in your hunch - the tag says it's a 230 V 13.1 A motor only. The other clue is that it says 4 HP, which is about right for these numbers - although note there was a period when every manufacturer lied about the motor HP on air compressors.

Is there a wiring diagram inside the access cover that you removed? That would be useful in case this neighbor of the guy you got it from also messed around with the line connection points as well. I'm not sure what he could do wrong given the simplicity of the connections, but then the propensity of people to mess stuff like this up has at times simply amazed me.

A very similar thread is here, BTW.

 

[kredden]

Nothing on the back of the access cover, that could be because looking inside there doesn't appear to be any way to change anything. All the other wiring looks OK as far as I can tell. I'm guessing what could have happened is that the guy I got it from didn't understand what the plug was and just went to Home Depot and got a replacement plug for 115 and put it on.

I was wondering how, in all my searching around, that I missed the thread you linked to above and then noticed that it was from yesterday morning. What a coincidence!

 

[tak1313]

How many gallons is that compressor? I can't imagine anything 60gal and up having a 120/240v motor

 

[finn]

How many gallons is that compressor? I can't imagine anything 60gal and up having a 120/240v motor

I have a cheap CH 120v compressor with an oilless pump and 60 gallon tank.

60 gallon tanks aren’t common perhaps with these cheap compressors, but they’re out there.

I use mine for filling bicycle tires, blowing sawdust out of chainsaws, and running air nailers (with a really long hose).

Overall, it’s pretty useless, considering the space it takes, but it filled a need at the time, and was cheap.

 

[micromind]

This is a classic symptom of a 240 volt motor being run on 120.

That motor is 240 only and will not work on 120.

 

[Beerhippie]

I'd say you are correct in your hunch - the tag says it's a 230 V 13.1 A motor only. The other clue is that it says 4 HP, which is about right for these numbers - although note there was a period when every manufacturer lied about the motor HP on air compressors.

Is there a wiring diagram inside the access cover that you removed? That would be useful in case this neighbor of the guy you got it from also messed around with the line connection points as well. I'm not sure what he could do wrong given the simplicity of the connections, but then the propensity of people to mess stuff like this up has at times simply amazed me.

A very similar thread is here, BTW.

What's changed? Manufacturers no longer lie about power ratings?

13.1 A @ 230 V would be right for four hp.

 

[Steve_P]

What's changed? Manufacturers no longer lie about power ratings?

13.1 A @ 230 V would be right for four hp.

By the "definition", yes. But electric motors aren't 100% efficient, more like ~80% (lots of variables).
My previous IR compressor was 240V 15A, rated 5 HP. Mathematically, without losses, it specs out to 4.8 HP.
Current Quincy is 240V 30A, rated at 7.5 HP. Math says 9.65 HP, double the current draw and double the IR's HP rating. But the reality is that it's more like 9.65 x 0.8= 7.7 HP, which is closer to the Baldor motor's rating.

In the case of the OP, he has a 240V motor that probably wants to draw 26A on 120V. I'm surprised it hasn't burned up yet.

 

[johnre]

What's changed? Manufacturers no longer lie about power ratings?

I guess all that’s changed is that they were caught at it on air compressors. So they just changed the game over to doing this on shop vacuums and leaf blowers.

 

[kredden]

How many gallons is that compressor? I can't imagine anything 60gal and up having a 120/240v motor

20 Gallons, nothing fancy. Here it is in all its glory, if I can get it running reliably I'll spend the time to clean it up.

 

[danielbuck]

that plug end looks new, someone probably just wired up the wrong end, couldn't figure out why it didn't work, and now you have it.

 

[Hohn]

What's changed? Manufacturers no longer lie about power ratings?

13.1 A @ 230 V would be right for four hp.

A lawsuit, that's what's changed.
In ~2004, a class action suit against CH, Devilbiss, IR and a couple other names in compressed air led to a settlement that corrected the "developed" or "peak" power shenanigans.

 

[u3b3rg33k]

By the "definition", yes. But electric motors aren't 100% efficient, more like ~80% (lots of variables).
My previous IR compressor was 240V 15A, rated 5 HP. Mathematically, without losses, it specs out to 4.8 HP.
Current Quincy is 240V 30A, rated at 7.5 HP. Math says 9.65 HP, double the current draw and double the IR's HP rating. But the reality is that it's more like 9.65 x 0.8= 7.7 HP, which is closer to the Baldor motor's rating.

In the case of the OP, he has a 240V motor that probably wants to draw 26A on 120V. I'm surprised it hasn't burned up yet.

that would only be true if it was a dual winding motor wired for 120V.

as a 240V motor on 120V, You'll just get less power. I think 1/4 of nameplate if ohm's law applies as I think it does. so it's a massively overloaded 1HP motor. you'll still get synchronous speed unloaded.

I'd guess whoever put the naughty plug on it had a naughty outlet for it.

 

[kredden]

Could be. I’ll wire up a new plug tomorrow and fingers crossed that’s all that is wrong with it.

 

[kredden]

that plug end looks new, someone probably just wired up the wrong end, couldn't figure out why it didn't work, and now you have it.

It is new, on of the PO's put a Husky cord on it, hence my confusion!

 

[nmk_61802]

Looks like this might be the same model:

Oil change 4 hp 20 gallon craftsman compressor

Hi all I have a 20 year old compressor a craftsman. I dont know where to fill the the pump. It has a 1/4 NPT at the bottom with a l shape drain. Thanks

www.garagejournal.com

Look at last few posts for motor info

 

[kredden]

Nice, that does appear to be the same one. His stickers are in a lot better condition that mine.

 

[kredden]

Well that was it, swapped over to a 20A 240v plug and it cranks on up to 100 psi with no drama. I had fiddled with the pressure switch screw, just need to adjust back to 125. Now time to clean it up and fabricate a replacement for the missing handle. Thanks for all the help!

 

[Wiz02]

Glad that you found and fixed the problem. FYI, my early 80s Cman compressor looks very similar to yours, but mine has a dual voltage capable motor.


Though I changed the motor electrical connections to 240vac a long time ago, I still remember multiple posts marked for 120 vs 240vac

 

[kredden]

Funny thing is that during all this I was picking up some stuff at a store and they had a much newer (but still almost 20 yrs old) upright 25 gal Husky compressor out front with a free sign on it so I grabbed it. Plugged it in and it wouldn't turn on, dug in to it and found that the motor brushes had completely worn away to nothing, just part of the spring left. Of course the brushes aren't made any more so I need to see if I can figure out if any of the more generic ones on eBay can be retrofitted. This compressor is 115v only, no 230v option .

 

[RTM]

found that the motor brushes had completely worn away to nothing, just part of the spring left. Of course the brushes aren't made any more so I need to see if I can figure out if any of the more generic ones on eBay can be retrofitted.

My local Ace hardware has random brushes in the loose screws section. Find something close and file it down?

 

[PCustoms]

How rusty is the inside of that tank?

 

[kredden]

How rusty is the inside of that tank?

Haven't looked yet, but there were only a few drips of water that came out when I opened the valve at the bottom.

 

[kredden]

My local Ace hardware has random brushes in the loose screws section. Find something close and file it down?

Yeah, I may try that. The outer casing's for the brushes are OK so I'm 3d printing a test block to see if I measured the dimensions correctly and will go from there.

 

[Shiftless]

My local Ace hardware has random brushes in the loose screws section. Find something close and file it down?

You beat me to it. That’s what I have done in the past. Carbon brushes are easy to reshape. The perfect tool to use is a 1 inch wide belt sander.

 

[Wamsutta]

This is a classic symptom of a 240 volt motor being run on 120.

That motor is 240 only and will not work on 120.

That's exactly correct. The motor wants 240V but is being fed 120V. So in order to get the same required wattage, it has to draw in more amperage to compensate for the lack of voltage. All that amperage is getting things hot and that's why the thermal overload trips.

 

[tvand13]

Funny thing is that during all this I was picking up some stuff at a store and they had a much newer (but still almost 20 yrs old) upright 25 gal Husky compressor out front with a free sign on it so I grabbed it. Plugged it in and it wouldn't turn on, dug in to it and found that the motor brushes had completely worn away to nothing, just part of the spring left. Of course the brushes aren't made any more so I need to see if I can figure out if any of the more generic ones on eBay can be retrofitted. This compressor is 115v only, no 230v option .

Do air compressors that big typically use brushed universal motors? Every 25 gallon compressor I've seen has an induction motor.

 

[micromind]

Do air compressors that big typically use brushed universal motors? Every 25 gallon compressor I've seen has an induction motor.

I've never seen one that size with brushes.

 

[kredden]

I wouldn't think so but this second compressor is only 1.7hp (maybe real? ), 26 gallon 120v 15A WL660900AJ. The motor is a LOT smaller than the one on the original compressor in this thread. I've got one of the brush holders out, trying to find a match. You can see the other one in the second pic on the upper left area of the commutator, it is down to just the spring acting as a brush.

 

[kredden]

I found one web site that actually had the brushes (MC030230AV) listed and I contacted them and they said they are out of production with no replacements. I've got an email out to Campbell Hausfeld asking for the specs on the brush but I doubt I'll hear back. Here is what they are supposed to look like and here is mine with the 3d printed brush part of what I think the approximate size should be 8mm x 11mm x 20mm.

 

[The Cobbler]

you should be able to source brushes with a similar size, you can easily file & massage them to fit .
let me look at my stash of junk to see what I have . I've got some scrap that I keep just for parts

 

[fitter30]

Don't wire a 120 vac reciprocal for 240vac. Years ago used a outlet on a roof of a hotel. Plugged a vacuum pump in one before i realized that the pump was going up in smoke it was to late. $500 pump up in smoke in a few seconds.

 

[The Cobbler]

also, with worn brushes could indicate a bad armature too

 

[AC-WC]

20 Gallons, nothing fancy. Here it is in all its glory, if I can get it running reliably I'll spend the time to clean it up.

That's the same as mine it is absolutely 220 and on a 20 amp circuit for me. It does have an odd plug with 1 sideways terminal, 1 vertical and the normal ground. I've had mine since 86 with minor repairs. Just did a pressure switch a few months ago and maybe 10 yrs ago a safety valve. Still no rusty water coming out of the tank so I'll keep using it.

 

[The Cobbler]

approximate size should be 8mm x 11mm x 20mm.

let me look at my stash of junk to see what I have

I looked , and I have a motor very similar from a compressor that is trashed, thought we'd be in luck, but they are 6.15x10.81x 27
sorry

 

[kredden]

Thanks for checking!

 

[u3b3rg33k]

That's exactly correct. The motor wants 240V but is being fed 120V. So in order to get the same required wattage, it has to draw in more amperage to compensate for the lack of voltage. All that amperage is getting things hot and that's why the thermal overload trips.

that's incorrect. please see my above post about this.

 

[nadogail]

I knew a guy who built a playhouse for his daughter, he wanted a 240 outlet for something and just grabbed a 120 outlet and ran 240 to it.

He did label everything, the 240 appliance was fitted with a 120 cord and plug.

That was 65 years ago, to the best of my knowledge there were no problems.

Maybe that same guy has worked on other projects.

 

[micromind]

I knew a guy who built a playhouse for his daughter, he wanted a 240 outlet for something and just grabbed a 120 outlet and ran 240 to it.

He did label everything, the 240 appliance was fitted with a 120 cord and plug.

That was 65 years ago, to the best of my knowledge there were no problems.

Maybe that same guy has worked on other projects.

Years ago, it was fairly common to supply a 125 volt outlet with 240 and label it. 250 volt outlets were hard to get back then.

 

[PCustoms]

Years ago, it was fairly common to supply a 125 volt outlet with 240 and label it. 250 volt outlets were hard to get back then.

What?

How many years ago was this?