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kb58
kb58 SuperDork
2/4/20 8:52 a.m.

I'm an EE, for what it's worth.

Like vacuum cleaner specs, pedestrian compressor ratings are a mix of BS, marketing. A 100% efficient 1 hp motor at 120V will draw 6.2 amps. That means that a "5hp" compressor needs 6.2 x 5 = 31 amps. But that's for a perfect motor, which doesn't exist. Figure 85% efficiency and it increases to 36.5 amps. These currents will be half as much for 240V, but the point is, mfgs play all sorts of games when it comes to power ratings. Disclaimer: Real (commercial) compressor manufactures tend to be more honest with their numbers.

Welder. Welder rating is the maximum current it can deliver, it has nothing to do with how little it can output. Interestingly, the expensive big machines are typically much more adept and have far better finesse at the low end than cheap welders.

dculberson
dculberson MegaDork
2/4/20 9:00 a.m.

Quincy makes a good compressor. That's what we use at work for our HVAC system. It has to keep our pneumatic lines charged up 24/7/365 and it does a good job. We get many years out of them. The last replacement was 2006!

AnthonyGS
AnthonyGS Dork
2/4/20 10:24 a.m.
kb58 said:

I'm an EE, for what it's worth.

Like vacuum cleaner specs, pedestrian compressor ratings are a mix of BS, marketing. A 100% efficient 1 hp motor at 120V will draw 6.2 amps. That means that a "5hp" compressor needs 6.2 x 5 = 31 amps. But that's for a perfect motor, which doesn't exist. Figure 85% efficiency and it increases to 36.5 amps. These currents will be half as much for 240V, but the point is, mfgs play all sorts of games when it comes to power ratings. Disclaimer: Real (commercial) compressor manufactures tend to be more honest with their numbers.

Welder. Welder rating is the maximum current it can deliver, it has nothing to do with how little it can output. Interestingly, the expensive big machines are typically much more adept and have far better finesse at the low end than cheap welders.

Got it.  Miller also posts input specs for their welders. My electrician has all 3 manuals, FWIW.

AnthonyGS
AnthonyGS Dork
2/4/20 10:28 a.m.

In reply to dculberson :

Good news.  The motor was heche en Mexico, but I know the unit is assembled and shipped from KY.  I need to check the compressor, some of them are made in Italy it seems.  I did buy the maintenance kit to get the extended warranty.  I have mounting pads (rubber / cork) and anchors to install it.  I need to get a 1/2" concrete bit for my hammer drill.  Once its wired in, I will figure out where to hang my hose reel.  

 

Rotaryracer
Rotaryracer Reader
2/4/20 11:02 a.m.
Gearheadotaku said:

Are you a SCCA member?  Is so, you can get off lease welders from Lincoln for a crazy discount, like 1/2 price. These are units used by NASCAR shops for a short period then turned back in to Lincoln. Got mine late last summer, works fine. Doesn't have a scratch on it.

It's a 180 amp 110/220 volt. Much more heavy duty than the Home Depot model of the same output.

Not to derail this thread, but this is highly relevant to my interests.  I went on the SCCA website and found some vague marketing-speak of 20-40% off for members, but the link just took me to the main Lincoln page.  Is there a trick to finding and purchasing these machines?  I am an SCCA member.

Thanks!

Jason

AnthonyGS
AnthonyGS Dork
2/8/20 5:54 p.m.

Got wiring done today.

 

Got floor anchors installed too.  Now I just need to decide how to hang hose reel and regulator.

You can also see the plug for the welder below the panel.

The lift power will route to the same location as the compressor via conduit and also get a cord end.

If anyone needs 10 ga wire I have extra and its expensive.

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