The Stovebolt Site Forums The Shop Area The Tool Chest Compressor oil in cold weather

I have a little shed that I work in since I haven't built my shop yet. It isn't heated, but it rarely gets below freezing. I have to run about a 50 cord to the shop and it is slow to kick on in warm weather, this cold weather is throwing the circuit over. Is it because the oil is too heavy? Can you run lighter oil in a compressor without harming it?

Super55,

I don't think it has anything to do with the viscosity of the oil but rather the voltage drop that is occuring over the 50 foot cord. A compressor draws a lot of current and even short length cords are not really recommended. What gauge wire is the extension cord? Is the compressor voltage 120V or 240V?

As an example, if the compressor draws 15A - 20A, a 10-gauge extention cord would be best.

As a point of reference, I live in Colorado and have been in my garage shop and started the compressor to pump up inflatable snow tubes when it has been <10 degrees and my compressor starts fine...

Hope this helps...

Burgie

Yeah.. I know the cord is really too long for best results, but it's the best I can do for the time being. It It isn't the cord that's keeping it from working because it's the same cord that's always been there. I am going to use the heater idea when I get ready to use it next time.

Don't change the oil in the compressor, and do get a better cord if you can, lugging it is going to burn out the motor.
An alternative would be instead of running the cord the fifty feet, can you move the compressor and run a fifty foot air line?
And maybe add an extra air pig tank in the shop and pressure drop won't be an issue.

HOL DE FONE
Let us get the facts first. Best to send photo of compressor motor nameplate. Otherwise send nameplate voltage and full load current (FLA). Dont bother sending HP they overrate these motors.

Does compressor have unloader and are you starting compressor on a zero pressure line IF NOT that really makes it hard starting.
THEN if your wire size is too small that makes the effort even worse.

After a good long run go out and feel the cord - it will be WARM and maybe OK
HOT no no no
Yes it is possible 50 feet of proper conductor will be a $100 but what is cost of motor?

Dan Bentler

I'm going to move it up to the house. That should take care of it. It's just a little Ingersol Rand 6 HP 120 volt.

120V is your problem, get it on 240 and it'll work much better, not hard to do, should be a diagram under the electrical cover

Bill

6HP electric motor running 120V??? Wow...

If you have 240V accessible, and if the motor voltage is switchable (easy to do)...definitely switch to 240V...

Remember Ohm's Law...double the voltage and half the current...

Did I say 6... pardon... 2. I must be thinking that's about the gallon size of the tank.. Yipes.. Sorry for the confusion. I moved it next to the house. Still need to build a shop with a 220 compressor in it next summer. I did manage to hook up my mig to the dryer outlet.

QUOTE Remember Ohm's Law...double the voltage and half the current QUOTE

NOPE nope and more nope
ON a resistive load double the voltage you double the current and power goes up by 4.

MOTORS which is what seems to confuse people. Wiring a motor for low voltage is in effect placing two windings in parallel so current is high and volt low.

Wire for high voltage ie 240 the windings are now in series BUT the current through them is same as when in parallel. SO volt doubled current halved Power equal either way.

Motor on 120 draws 10 amp let us say. Each winding is drawing 5 for total of 10.

ON 240 each winding still draws 5 amps they are in series so current is 5 amp. Volt drop across each winding is 120 for total of 240 across the two in series.

120 x 10 = 240 x 5 Power is equal

Dan Bentler

Uh ...yeah sure....whatever you say......

Well, I guess I am confused? I have an extensive collection of woodworking tools in my shop. Nearly 90% of them are dual voltage. In every case, the nameplate will list voltage and current.

As an example I looked at my drill press; the nameplate data is:

Voltage: 120/240 & Current: 12/6

My tablesaw is:

Voltage: 115/230 & Current: 15/7.5

Now, to me, that implies that if I double the voltage, the current draw is halved?

Yes, with a purely resistive load the relationship between voltage and amperage is directly proportional. If one increases so does the other proportionately. With an inductive load the relationship is inversely proportional; increase the voltage and you'll decrease the amperage...

So...am I missing something here?

exactly right Burgie, the equation that matters is P=I*E, a 1 horse motor is a 1 horse motor on either voltage

Bill

Burgie:

"Remember Ohm's Law...double the voltage and half the current..."

I've been out of college for over 40 years but didn't we learn that "power" is measured in Watts and it's power that the utility companies are selling, not voltage or current?

In that case, would converting the motor voltage from 120 to 240 make any difference?

the difference it makes Ray, is using half the amps and extending the motor life, got nothing to do with who sells the power or how much it costs ... as I pointed out just above you, the power is the same

Bill

Inside the motor it does not matter. The motor will draw same power regardless of hooked for high voltage or low voltage.

On the Line feeding the motor by going to the higher voltage and lower current you can reduce conductor, starting relay, and overload protection size. Of course going from 120 to 240 adds another conductor so if a long run what you save costwise on "smaller components" may get eaten up by added conductor cost. There may be some savings from reduced I2R loss in conductors but when you figure you dropped a conductor size or two it may come out to a wash.

Dan Bentler

Folks,

I understand the electrical physics of the motor and was merely trying to keep things on a very high, elementary level. Perhaps I shouldn't have included the reference to Ohm's Law?

So, Super55, these are practices I follow in my shop as it pertains to electric motors:

1. If the motor is dual voltage, I always run it at 240V instead of 120V.

2. If possible, I plug the tool directly into the wall outlet. Most of my tools are on mobile bases so I have the ability to move them around to accomplish this.

3. If I use an extension cord it is the shortest possible length. (I buy the cords from the bulk spools at Lowes or Home Depot and put the ends on myself so I can customize the lengths).

4. My extension cords are always oversized. As an example, if the factory cord that came with my thickness planer is 12 gauge, and I need to use an extension cord, I use my 10 gauge extension cord.

Now, these are the things that I do that seem to work in my shop. Most of my tools are Delta, Rockwell and Dewalt, all are industrial grade and most are at least 20 years or older. I have never had a motor burn up on me due to poor cord management practices.

I hope this helps you...

Burgie