Genny HELP please

[hk_fz6_05]

Ok so spent the day in the garage. Recently acquired a genny (no power out there) to run a compressor off. Got them both used but made sure (I thought) to have enough spare power on the genny to run the comp easily. Well. Not happening.

I turn the genny on (runs beautifully), let it run for a while to warm up, then hook up the comp and switch it on...and ....blah. The genny dies straight off.

After a couple of tries I managed to keep the genny going by adjusting the fuel intake, but only just (it was literally bouncing up and down so hard I had to steady it by hand to avoid it bouncing around the garage floor) and even then it didn't fire up the comp in any useful way.

So having very little experience in these matters I come to you for help. I've included the data on both machines and it would seem to suggest that I shouldn't be having any problems, so why am I? Am I missing something glaringly obvious? (I know the comp runs off the mains grid)

Any help appreciated!!!

(the genny is pic 1 and comp is pic 2)

 

[Solarservant]

How big is the generator (Watts) and what's the start-up amperage draw from the compressor? Does the output from the generator run through a breaker? What's that amperage rating? Have you tried running anything else on the genny? You should try something smaller and see if it continues to run.

 

[hk_fz6_05]

the generator runs 2,3kW, the comp (if I read the pics right) runs 8,2 A.
It does run through a breaker - hadn't thought of that, but if it manages to run (just) from twiddling the fuel intake, then the breaker amperage shouldn't be a problem, should it?
I'll check what the breaker circuit says, run something lighter off it and get back to you. thanks!

 

[Solarservant]

Pretty small generator, and I'm betting that the start-up on the compressor pulls way more than the rated amps, at least 1.5x. Are you in the UK? You would be looking at 50hz/230VAC nominal? So 1.5 x 8.2=12.3A (for a few seconds at most). 12.3 x 230VAC=2829W. That could be your issue, although I am wondering why the breaker isn't popping right away. Is the genny really old and tired?

Off to work. Let me know when you get a chance...

 

[dpaul007]

I wouldn't take your calculations from the peak output numbers, the generator can only sustain that power for a small amount of time. Companies pull this max power crap with speakers and amps, too. The generator is rated for 2000 watts (and 2300 watts for a short amount of time), and just the running draw on the compressor is between 1800 and 1900 watts. And as Solarservant already mentioned, when the compressor starts up, it's pulling more than that.

 

[hk_fz6_05]

interesting maths, (craptastic)
thanks for the feed back - I just came off yet another ungodly busy night shift and will get round to testing something else on the genny later today. Will post then.

Oh yeah - not in the UK but mainland Europe, 220 VAC and 50Hz is right though.

:thumbup:

 

[Motogiro]

Another thing to think about is does the compressor have a properly working decompression valve?
Compressors use a boat load of current to start.

Sent from Moto's Droid using Tapatalk 2 :mikebike:

 

[hk_fz6_05]

I'm pretty sure SolarServant is on the money with the first diagnosis unfortunately - tried running my 500W angle grinder off the genny and went without a hitch (although there is an audible dip in revs on the genny when I first hit the switch).

The breaker on the genny is rated 16A so no issues there. I think there's just a lack of juice to get the comp running - oh well got the genny on the cheap, guess I'll get a more umphy one.

Thanks for your help everyone!

 

[hk_fz6_05]

PS is there any way to determine the start up power draw of the comp?

 

[Solarservant]

You'll need a clamp-on meter to measure AC amps through the power cord. Watch the initial amperage draw as your compressor is just starting. Some better meters have a Min/Max function that will allow you to see what you peaked at.