Generator won't power compressor....ideas?

[Raspy]

I doubt that. it's just people don't read the tags / or understand what they read.... or how the co listed the info / did the conversion.

rms and peak.. etc.

I BET you his comp is listed using PEAK wattage, then the hp conversion was done. looking at the rms conversion and the hp listed.. that would drop the rms hp into the 2.x range.. right near your calculation.

I bet somewhere hidden on that tag or in the manual it states a peak measurement..

For those not familiar with rms, peak and peak to peak.. hit an ac/dc / electronics 101 coursebook...

Many compressors advertise a horsepower rating, but the motors say SPL instead of the actual running horsepower. It's common to see a "4 HP" compressor that actually has a 2 1/2 HP motor and the CFM confirms the rating. A true 5 HP compressor will say 5 HP on the motor plate. Others will advertise 5 HP, but the motor will say SPL and the running amps will be far below 5HP.

I think the exaggerated claims are listing the locked rotor amps and converting that to some advertising claim. I call it "Sears horsepower". It's commonly done on shop vacuums where they draw 13 amps at 115 volts, but claim to be 5 hp or so. Bogus. It would be equal to the amps it draws as it explodes, not as it runs. It's misleading. Best just to look at the CFM at 90 PSI for comparison o compressors.

 

[Soundguy]

if he has a 110/220 motor.. it's gonna for sure be compatible with 60hz and or single phase if sold for the domestic market.

 

[Soundguy]

I think the exaggerated claims are listing the locked rotor amps and converting that to some advertising claim. I call it "Sears horsepower". It's commonly done on shop vacuums where they draw 13 amps at 115 volts, but claim to be 5 hp or so. Bogus. It would be equal to the amps it draws as it explodes, not as it runs. It's misleading. Best just to look at the CFM at 90 PSI for comparison o compressors.

well.. that's pretty much exactly what I said..

peak draw.. possibly at stall / max torque, converted to hp figure.

and yes.. i'd call that the same type of logic used to rate small gas engine hp.


somewhere in some lab, using 0w1 oil, and straight ether for ful, with no belted equipment, no pumps.. no fans , etc.. carb running out of epa spec in a manner the end user could never see it operate, at an rpm band 200 nanoseconds before it detonates on the test stand. they clock that hp .. and then poof.. you have an engine the size of a basket ball making 25hp..

 

[Boeing]

You guys are amazing...and thank you.
I will wire to 230V. I bought a male 4 prong plug to go into the generator and 15' of 10/3 wound wire.
And....you're right about the motor too. 4hp PEAK, 2hp running. The compressor is a campbell hausefield vt6196 from about 1993. It puts out 5.8 scfm at 90 psi. Max pressure 120. I like the coiled air line idea too.....
Thanks again.

 

[Soundguy]

yep.. I figured it was a peak hp listing. IE.. the max current it could ever be made to draw.. not something you as the user will ever really see..

pretty common listing nomenclature / method nowadays.. bigger numbers.. looks better...

 

[daybreak1998]

Howdy,
Compressor with a 4hp motor? And that thing has a standard NEMA 5-20 (20amp/125v grounded plug) like your standard but with the right blade sideways? I have a compressor which is a 3hp unit that is also 120/240 capable, which is wired 115, with standard plug, and it starts fine here. If that compressor actually has a 4hp motor, then thats gonna be to big for your standard electrical.

Get a L14-30 twist lock plug which then goes to a NEMA 5-20 (its only about 2 feet long) That way you are going off the 120/240 30amp socket on the generator. L14-30P to dual 5-20R

Even that might not work. Re-wiring the compressor for 240 would be the better way. You would then also need a 240 plug at your shop, or where ever it sits. Are you trying to use it out in the fields?

NOTE; motors really like to start easier with 60Hz cycle. Make sure the generator is really right on the mark.

 

[chim]

Sum Ting Wong

1. Who makes a 4HP motor? Gimme a list of manufacturers [grin]

2. "4HP Peak" has nothing to do with rms/average/peak, etc. It's a sales pitch calc only.

3. Other than watching cute squiggly lines on a scope, the only measurement that means squat is rms (aka effective). RMS is what your clamp-on ammeter and voltage meter display.

4. Full load current for a 115V, 1ﾘ motor is 16 amps:

Electrical Motor - Full Load Current

 

[xzcVAbc5]

You guys are amazing...and thank you.
I will wire to 230V. I bought a male 4 prong plug to go into the generator and 15' of 10/3 wound wire.
And....you're right about the motor too. 4hp PEAK, 2hp running. The compressor is a campbell hausefield vt6196 from about 1993. It puts out 5.8 scfm at 90 psi. Max pressure 120. I like the coiled air line idea too.....
Thanks again.

Your generator will thank you. When you have a generator capable of spitting out 120V or 240V at the same time and you plug in a 120V you are only using half of your generator. When you wire 240V you're using the whole voltage and are able to draw all of the power from the generator from one device.

 

[SPYDERLK]

6500W at 120V = 54A. 6500W at 240V = 27.5A


Neither one is 4 times the rated amps at the running voltage, but probably plenty to get the compressor started. You just need to get that power to the compressor in a practical way.

True, but 240V gens dont work that way. Full rated power is only available from the 240. 6500/240 = 27.5 is the amps available. Only half power will be available from each 120V leg of the spit since the gen will be fused to protect its windings from current over 27.5A. That compressor will never start on the 120V output of that 240V gen.
larry

 

[Soundguy]

take his 4hp peak #.. convert to watts.. then convert to rms, assuming that number is a peak watt rating.. now use the hp conversion and go back to hp... the numbers bang out almost perfectly.

so yes is does matter.. completely.

you just have to understand electronics and economics...

. "4HP Peak" has nothing to do with rms/average/peak, etc. It's a sales pitch calc only.

3. Other than watching cute squiggly lines on a scope, the only measurement that means squat is rms (aka effective). RMS is what your clamp-on ammeter and voltage meter display.

4. Full load current for a 115V, 1ﾘ motor is 16 amps:

Electrical Motor - Full Load Current