Running a computer with a generator
February 7, 2007 7:55 AM   Subscribe

I need to install a branch line from my emergency generator circuit that will feed my wifes work computer at home. I always assume that voltage from my Honda generator/welder is going to be quite dirty. Do I need more than a surge protector and line conditioner to prevent her system from being damaged?
posted by Raybun to Computers & Internet (8 answers total)
I'd probably put a UPS on there, one that *does* surge protection and line conditioning. It'll make up for any drops.
posted by SpecialK at 8:14 AM on February 7, 2007

Plug the computer into a small UPS, then plug the UPS into the generator. I've used this approach numerous times without any damage to the computer.
posted by Svenny at 8:15 AM on February 7, 2007

If you buy a high enough quality UPS it should clean the incoming generator power when it detects a line fault. I might add that my only experience in this field is with datacenter UPS's, and not sure if there is a viable consumer item. Good luck.
posted by ronmexico at 8:18 AM on February 7, 2007

I agree, use a UPS. The little device (POV?) used in most common power strips to provide surge protection is not that effective and it will lose effectiveness as it ages.
posted by 14580 at 8:21 AM on February 7, 2007

Note that not all UPSes do surge protection though ...
posted by SpecialK at 8:39 AM on February 7, 2007

The little device (POV?)

posted by b1tr0t at 9:11 AM on February 7, 2007

Most PC's built since 1995 use switching type power supplies, which are generally insensitive to the waveform of the AC line, so long as the voltage peaks of any non-sinusodial transients are not more than about 1.5 time RMS value. And if your PC is new enough to have SATA drives, you may even have a mandated high power factor power supply, which has additional filtering and power factor correction for greater efficiency mandated by EU and other regulatory bodies.

Thus, if you have a fairly new computer, the quality of the power coming from your generator is fine, but you might want to have a small UPS between it and the computer, anyway, to hold up the computer during the period you're switching over to generator power. For that, you should generally look for one of the "online" type UPS units, which constantly have their inverters and batteries in series with the load they protect, thus avoiding the several hundred millisecond switchover time of cheaper Back-UPS style units, which only switch over to battery operation for their inverters after the AC line has dropped for a few hundred milliseconds. UPS units need to be connected to generators and power sources very carefully, however.

Older style units could backfeed the power lines to which they were connected, and shock servicing personnel, or try to drive big appliances or other upstream loads with disasterous effects to themselves. Most modern units have rectifier bridges that prevent this, but you need to check when purchasing.
posted by paulsc at 2:18 PM on February 7, 2007

Paulsc is on the money however you might find the term 'line interactive' used by UPS manufacturers rather than online. The cost difference is not too significant but the quality difference is.
posted by bangalla at 3:16 PM on February 7, 2007

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