OT: Powering colour laser printer from a generator

Can anyone advise on the following issue:
I need to power a colour laser printer away from mains power from a generator. I'm well aware that the high current a laser briefly draws as it starts printing a job is going to cause problems.
I haven't yet bought the laser printer, but if anyone knows of a model with low inrush current it would be helpful.
I have a choice of generators available, all digital sinewave types, in outputs of 1kva, 2kva, and 6kva. I also have to power 3 computers (of which 2 laptops), 2 dye-sub printers and 2 inkjet printers as well as networking gear etc from the same generator. I've powered everything but the (new) laser in the past from the 2kva generator without issues.
So, what is the answer? I notice the spec of one HP I was looking at had a peak inrush current of 40 amps as it starts printing. My 6kva generator can provide 22amps max....
Ideally, something like a UPS inline that can cope with the high peak current is the answer, but I'm not aware such a model exists, without going to massive plant type units.
Any ideas?
The obvious answer is to not use a laser and stick with inkjets.... I'd really rather not do that if at all possible, but that's another story..!
Alan.
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Alan wrote:

Anything modern with an "instant on" fuser is going to have a high transient current demand... You may have more luck with an older style "slow warm up" printer.
Some of the LED printers are slightly less juicy than other "lasers". Might be worth looking at the specs on an Oki model. Note that many of these are GDI[1] printers, so you will need to be running some version of Windows to print.
[1] Which also lowers the consumption a bit since they don't have the same computing power in the printer as other "smart" models - they leave the rasterisation to the printer driver on the computer.

The computing kit sounds like it is probably less than 1kVA by itself (assuming you have a TFT monitor on the non laptop PC).

The biggest genny you can find, and some careful choice of printer with a bit of measurement and experimentation sounds like a good idea.
I would also put all the other IT kit on a line interactive UPS so that if the printer does make a big notch in the genny output from time to time it does not effect the computers.

If the inrush for the printer is just to feed the fuser, then you may get away limiting the inrush current a bit. It would cause a slightly slower warm up, but may not have much effect after that. This could mean the first page out of the printer after a period of not printing does not get fixed correctly.
--
Cheers,

John.

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I've never used a digital generator over 1kVA, or that wasn't one of the recent Chinese production ones. None of these were a happy experience in terms of powering electronics from them, particularly audio PA kit.
Useful generators IMHE though have all been chunky great electro- mechanical things generating high quality sine wave outputs, and with varying competencies of regulator. I've had trouble with the voltage drooping under sustained load, but never seen one that made me worry about its waveform. I've run lasers from "builders' 2kW+ site generators" plenty of times, and so long as it was mechanically large (i.e. high inertia) and had a post-WW2 design of regulator, then it was fine. I've actually had less trouble than from cheap poor-waveform inverters off batteries.
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In an earlier contribution to this discussion,

Are you *sure*? - that's 10kVA! Is it normally powered off a 13A plug because, if so, the fuse ain't going to last long!
Are you sure that this isn't 40A at low voltage (maybe 12v) derived from its internal supply rather than from the mains?
--
Cheers,
Roger
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Here: http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=bpl05920&prodTypeId 972&prodSeriesId%470&locale=en_US
"Power Consumption : 240V; maximum 615W; average 200W; 200W when printing; 6 W PowerSave (sleep) mode. Peak inrush current is 240V; 40A peak (20 degrees C, from cold start). "
And that's for a HP1100 mono laser printer.
The inrush will be for a split second I imagine, so therfore can be delivered via a 13a plug without issue, and it's duration isn't enough to trip a MCB, but if the supply is a generator that can't deliver sudden peaks I may have a problem.
Alan.
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In an earlier contribution to this discussion,

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=bpl05920&prodTypeId 972&prodSeriesId%470&locale=en_US
Well, it certainly *says* that - but lower down it says "Minimum power supply capacity 2.3A". I can't help thinking that there's a decimal point missing in the 40A figure.
I think you should contact HP to clarify - although finding anyone who *knows* could present a challenge!
--
Cheers,
Roger
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On Wed, 14 Feb 2007 22:06:26 -0000, "Roger Mills"

Many Switching power supplies draw an enormous current for the first cycle, it then diminishes very quickly as the the main capacitor is charged. 40A is a very reasonable figure for the first cycle.
If the source (generator) is not able to supply this, the voltage will sag for a few cycles as the capacitor charges, then all will be normal.
A computer being run off the same generator may crash, a lamp wil flicker, a UPS will go to battery for a few seconds.

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Sounds like youre misunderstanding inrush current, which is essentially irrelevant here. Inrush is too brief to have any effect on anything. What counts is the power consumption of the fuser, which wont be anything like 40A, nor 13A. Ie the 615w figure.
So a 1kW gen would run one of your printers, but not 2.
If you need to power a printer off a gen of less than 615W rating, generally it is be effective to add a series impedance to the fuser heater to limit power draw. The downside is it will be slower to warm up, but this is trivial for most apps.
Your total load figure can be intermittent rating, as the printer only draws these loads briefly. OTOH a bit of margin is wise, as gen engines are not things that stay running at peak performance all the time.
There is one other problem, voltage surges. While more or less a non issue on mains, on portable gens theyre a real problem when running a mix of electronic and switched power loads, which is what a laser printer is. A meaty surge absorber would be wise.
There is also the q of what voltage the gen will really supply under full load, and whether the printer, pc etc will tolerate it. IMLE the gens I used dogged down badly when fully loaded, and if you have a choice at this point I'd go for equipment able to run off 110-240v without need to operate a switch to do so. 240v kit may well be fine, but it isnt always so.
Gen frequency is often way out of spec, but this shouldnt matter. It also should not be a prob with an electronic invertor type.
NT
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Hello,
I've monitored the output voltage and waveform from one of the inverter generators in the past and found it suprisingly good, it seems to hold the voltage very steady as load is applied and removed. The same cannot be said for a traditional Honda open-frame generator I also have, as the mechanical governor cannot react in time to sudden load changes, and if a large load is switched off the output voltage peaks alarmingly high, and as you say the voltage drops when it gets loaded.
I've run a fair bit of computer kit from the inverter generators last year without issue. I usually used a line-interactive UPS inline to a desktop PC but I didn't see the UPS complain about undervoltage once.
I've found a HP3500 colour laserjet in work I can test with a generator to see how they get on, before buying a laser myself.
Alan.
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Alan wrote:

The colour machine will have higher power requirements than a conventional mono one. So if it can hack that then it ought to be ok with the mono one.
--
Cheers,

John.

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snipped-for-privacy@care2.com wrote:

Many of the better UPSs have an additional filtered (but unsupported) output designed for this sort of application.
--
Cheers,

John.

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Not the OP, but Laser printers commonly use a *long* (30-35cm for an A4 printer, longer for A3) halogen to heat the fuser roller so I'm not too surprised by that figure. Some of the new lasers use a ceramic heater for the fuser that is in direct contact with a mylar like heat transfer tube, they use less power but I'd still expect a fairly high inrush current. Colour lasers also have to drive four cartridges and a photo-conductor belt or some similar arrangement so the motor current is likely to be higher than a mono one as well.

Al the fuser assemblies I've seen have been mains powered, makes the cabling cheaper and you can switch it with a cheap SCR.
--
Clint Sharp

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On Wed, 14 Feb 2007 12:51:55 GMT, "Alan"

Inrush is not when it starts printing.
Inrush is the power supply charging it's capacitor(s) from dead, this is usually only when the power is first applied to a device not when the device wakes up from power save or changes modes such as the start of printing.
The only way to know for sure if it will work is to test the complete system.

If other equipment is running when you first turn on printer, you may experience a power sag and subsequent crashes, a UPS for the sensitive devices should mitigate the power disturbance from the laser printer.
Laptops (with a functional battery) are extremely tolerant of power problems.
A Toshiba 1400 series online UPS will fix almost any power problem.
If you feed everything else from a UPS of any type, it won't matter what the laser printer does to the generator as long as it keeps running and recovers in a minute or two.
If you feed the laser printer from an ONLINE UPS then it's inrush will not impact the generator.
A line interactive UPS will either pass the inrush surge to the generator or shut-down,

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wrote:

Thanks, will test in the next few days, sounds like it should be OK.
Alan.
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