Piero
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if 6 times the run current was true, would that not make most air compressors pop there 13amp fuses ?????
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if 6 times the run current was true, would that not make most air compressors pop there 13amp fuses ?????
Piero
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Now, I am not saying the post I will copy in, is correct, but I found this on an other forum, The chap replying to a similar question did test his own air compressor, his reply I will copy and paste below
Pasted "
Just ran up my 3hp CompAir for you.
Motor plated at 15A for full load (it's 20years old) General Electric old skool moving coil clamp meter.
Inrush on the needle peeks at 25A, running current is 10A from Zero psi.
A brand new motor would be made today with a much higher efficiency, but the pump being new would be stiffer to turn.
SOD
Lathe power requirement varies according to design.
A 6inch chuck is a heavy lump to accelerate a 4inch is not
Gear drive has large losses, a belt drive has not
How long is your piece of string?
Pasted "
Just ran up my 3hp CompAir for you.
Motor plated at 15A for full load (it's 20years old) General Electric old skool moving coil clamp meter.
Inrush on the needle peeks at 25A, running current is 10A from Zero psi.
A brand new motor would be made today with a much higher efficiency, but the pump being new would be stiffer to turn.
SOD
Lathe power requirement varies according to design.
A 6inch chuck is a heavy lump to accelerate a 4inch is not
Gear drive has large losses, a belt drive has not
How long is your piece of string?
So, based on start current being six times run current, the Shhh type of compressor might actally be ideal, almost maxing out the Anker 767 surge capacity on start up, with a small margin. Question is, what else might be running off the battery bank at the same time?
sako243
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Fuses are quite slow blow in nature. A typical 13A fuse will handle much more surge, in fact a 13A fuse is supposed to withstand 1.6x the rated current for 30 minutes (BS 1362). It only blows at much higher currents (1.9x ish).
www.pat-testing-training.net
Why does a 13A fuse not blow at 13A?
The rated current is the current that it can pass without not overheating the plug. A 13A fuse will allow a current of 20A to pass without blowing.
carbon
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I work mostly with pressure washers and use a digital current clamp meter when testing but the sample rate isn’t fast enough to detect the maximum peak current but I still can see currents in excess of 25 amps at start up with some motors. When a motor capacitor completely fails the fuse usually lasts up to about 1 second, looking at the chart in the above post the fuse will then handle about 80 amps before failing.
not done it yet
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We could, now we know the transient maximum current, be suggesting a two horsepower compressor?
I would expect, with a maximum continuous rating of 2300W there would be a transient overload quoted (usually for a given limited time before tripping). As this does not appear, at first reading, to be needing more than occasional recharge of the receiver, the user could turn off other power consumption for the short time required for a single re-fill.
I have a 2000W inverter I can use with battery power. I’ve never tried using it for running my three HP compressor - the inverter is completely isolated from the grid, when in use.
Many modern units can take power from the grid for excess power, if needed. A second, or perhaps much less, above the continuous rating of the inverter may not trip the system. I can run my one horsepower mill and lathe without trouble - but like any sensible machinist, they are never both in operation at the same time.
Virtual ‘one liner’ posts, like the OP made, are (frankly) often a waste of responder’s time - as can be seen from this thread progression.
I would expect, with a maximum continuous rating of 2300W there would be a transient overload quoted (usually for a given limited time before tripping). As this does not appear, at first reading, to be needing more than occasional recharge of the receiver, the user could turn off other power consumption for the short time required for a single re-fill.
I have a 2000W inverter I can use with battery power. I’ve never tried using it for running my three HP compressor - the inverter is completely isolated from the grid, when in use.
Many modern units can take power from the grid for excess power, if needed. A second, or perhaps much less, above the continuous rating of the inverter may not trip the system. I can run my one horsepower mill and lathe without trouble - but like any sensible machinist, they are never both in operation at the same time.
Virtual ‘one liner’ posts, like the OP made, are (frankly) often a waste of responder’s time - as can be seen from this thread progression.
MetalMonkey
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Generally the more relevant information you can supply to start with, the greater the accuracy of the responses you will receive.
Especially when you want a solution which is outside the norm for a seemingly arbitrary reason.
A lot of people may think they need something, but they often don't - or just haven't considered or been aware of an alternative - that is the benefit of having a variety of replies.
For example - I find a hand held cordless blower is just the trick for dusting stuff off quickly without the hassle of getting the air line out. However, it is not much use for blowing up a tyre...
Piero
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I was actually shopping for a clamp meter with inrush mode, it would be interesting if nothing else
sako243
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That is extremely valid. At my old company it was known as the Roger effect. Basically our technical authority in the group was the first contractor our clients had ever had turn around to them and say hang on... Are you sure you want to do that? Or more often - are you being morons?
The end result is it (usually) ended up costing a bit more initially but they got a far more capable and versatile system built out of it. Over the years it trickled down such that junior engineers would often do the same thing - question what they actually wanted and propose alternatives.
I've got a 100L Clarke job with a belt drive. It's a few years old (& in the workshed so I cant recall details).
What I can say is that it's surprisingly quiet, and what noise it does make isn't harsh or irritating - way quieter than the bloody racket the direct drive things make.
All in all a cracking little unit, handy (it's on wheels with a pull handle) & does its job well.
Never considered the start load, as it's always fired up easily with no drama.
What I can say is that it's surprisingly quiet, and what noise it does make isn't harsh or irritating - way quieter than the bloody racket the direct drive things make.
All in all a cracking little unit, handy (it's on wheels with a pull handle) & does its job well.
Never considered the start load, as it's always fired up easily with no drama.
not done it yet
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I remember the tight-fisted purchases at a place I used to work at.
One obvious example was a 3.5kW cooler for a XRF analyser with a 3.5kW X-ray hube. They forgot, or didn’t consider, the EHT supply for the tube, which produced another approx 1.5kW of surplus heat. Of course, they blamed the installation, not their poor design specification….
There were so many similar (and some were hugely costly mistakes (or tight-fisted estimates for design specifications) resulting in machinery that was poorly matched with the process.
Is this "power station" off the Solar Array basically just an Inverter unit?
If it is, then I'd check to see if it has a stated max motor size that's allowed to be started off it (some US-made Inverters for off-grid systems used to state this - e.g. a Trace/Xantrex 3kW Inverter/Charger stated a max 1hp motor).
Where we had off-grid properties (single inverter) with workshops and/or borehole water pumps, then we'd have those items on a separate circuit to the battery-inverter-generator circuit, so these bigger items could only be supplied directly off the generator output.
If I've interpreted the "power station correctly, & on that basis (& given the pre-mentioned approx. 6x transient start current) - then no way would I be wanting to start a compressor off a 2.3kw inverter directly.
As an add-on.... the 6x starting for 1ph motors is a rule of thumb, as there is the factor of whatever the motor is driving.
A motor that spools-up with virtually no load on it may well take less than 6x (& what inrush there is will be for a very short duration).
Something with a lot of weight/drag on the motor (e.g. an old-school Wadkin Planer or suchlike) might push the transient to say 10x, & for longer duration.
A motor that spools-up with virtually no load on it may well take less than 6x (& what inrush there is will be for a very short duration).
Something with a lot of weight/drag on the motor (e.g. an old-school Wadkin Planer or suchlike) might push the transient to say 10x, & for longer duration.
brightspark
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i clocked my 3hp motor running at 12,5amp flc and 55 amp starting
Piero
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interesting
Sorry to hijack, but it’s kinda relevant..
SGS will be stocking a slightly down-rated version of this compressor at around half the cost. I like the space saving design, and think it’ll be good enough for my needs (future spraying, air dusting, tyres etc). It’s only a 50L reservoir, and the OP was after 100L, but what’s the opinion of the eperts here please?
SGS 50 Litre Oil Free Direct Drive Vertical Air Compressor - 4.3 CFM, 2HP, 50L
Introducing NEW Air Compressor from SGS - with vertical 50 Litre receiver tank is ideal for DIY and trade applications such as spray-painting, tyre inflation, nailing and stapling. Upright design.
www.sgs-engineering.com
Currently using a borrowed Bambi slient (oil lubricated) fridge style thing. Expensive new and less oomph.
Ta.
Smallfry
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Start up current is 3X run current. Thats what I learned too.
