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Running a computer off a generator with a ups?

Running a computer off a generator with a ups?

Hi I'm planning on running my fairly new computer using a ups that's being fueled by a gasoline generator, I'v heard that it should be safe to use like that but I wanted to get a second opinion. Any thoughts?

RE: Running a computer off a generator with a ups?

Ah, your turn in the barrel is about to come up...

It is safe BUT you will find that your typical UPS that looks at normal commercial power is completely freaked-out by the usually out-of-spec power that small generators produce. I've seen many of those small UPSs go into UPS mode while the generator is running just fine supplying power. This means the UPS is typically going dead running the load even though power should instead be supplied by the generator.

It may work fine. I'd estimate about 60% of the time it does not work fine. consider getting your generator and then trying UPSs until you find one that works with your generator.

Keith Cress
kcress -

RE: Running a computer off a generator with a ups?

You need a generator and UPS designed more toward the commercial market spec requirements.

  • More precise generator frequency and voltage regulation
  • UPS designed for operation on generator power.
Lack of generator precision (frequency and voltage regulation) and a consumer quality UPS (lacking adjustable parameters to accomodate generator power) is the issue as pointed out by itsmoked above. The likely end result is the UPS staying in battery mode and failing to switch over to accept generator power.

UPS units for the commercial market will have adjustable parameters that permit operation on properly regulated generators. Namely the window of acceptable frequency, acceptable voltage limits, and transfer delay (amount of time the UPS samples incoming power to determine if acceptable) can be changed per manufacturer recommendations for operating on generator power.

I'm using an older technology, but robust design UPS that came off a commercial job site, a FERRUPs 1.4kVA UPS to power all the electronics in my home. The UPS, with parameter changes per the UPS manufacturer's recommendations for use on generator power, runs fine on my commercial quality generator..

RE: Running a computer off a generator with a ups?

Yup. The old Ferrups line was an extremely robust and
forgiving UPS. Hated to see them disco'd. Emerson
messed up a few more also. :(
The present-day alternative is a true on-line backup
power system. A bit more expensive to implement.
Most have software-defined parameters, and can be
easily made to accommodate wide inputs variations.

RE: Running a computer off a generator with a ups?

Finding a little 1.4kVA unit with configurable parameters might take a bit of searching. Very few small units offer that kind of configurability, or at least those that do have the capability don't make it available to the user.

RE: Running a computer off a generator with a ups?

The 1.0+kVA Smart-UPS offered by APC allows quite a bit of 'adjustment' and could be a solution if you have a problem.

Keith Cress
kcress -

RE: Running a computer off a generator with a ups?

I stand corrected Keith - thanks.

RE: Running a computer off a generator with a ups?

Hi Scotty; They have a couple of switch settings that open up the "region of trip".

From their lit:

Quote (APC)

Adjustable voltage sensitivity Provides the ability to adapt the UPS for optimal performance in specific power environments or generator applications.
Adjustable voltage-transfer points Maximizes useful battery life by widening the input voltage window or tightening the output voltage regulation.

Keith Cress
kcress -

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