Tell that to Panamax. Their top of the heap UPS wouldn't work on gen power, while a cheap Minuteman would.


Fact!

The fact is that any UPS that works on utility power will work on generated power as long as the generator voltage and frequency output is within spec.

Many generators don't output very clean power and will cause UPS devices to shut down.  This is actually a good thing because if the power coming out of the generator is so far out of spec that it shuts down the UPS, then you probably don't want it powering your electronics anyway.

From my understanding, generators run best at or near rated load.  If they are under or over utilized it's more difficult for the regulator to output clean power.

It's possible the cheap Minuteman just wasn't sophisticated enough or did't have the feature to shut it down in case of crappy power.  Many UPS and even power conditioner devices will shut down if voltage or frequency is too high or too low and some even have settings to change how sensitive they are.

I got a call 3-4 months ago from a client complaining that my equipment racks didn't stay on line with the generator.  The original install was over 6 years ago so I looked at my notes and the networking, telephone and A/V required for two TVs were on the generator.

Met the electrician onsite and sure enough, once cut over to the generator the racks went off including the gear that should be on backup.  Tested voltage going into the rack and it was 170-195vac!

Ended up being a faulty voltage regulator in the generator.  Once it was repaired everything worked as expected.  In this case I was actually happy that the APC UPS units shut down to protect the gear.  The client had damage to several appliances which was probably related to the generator.

I put a Panamax in my rack because I needed something anyway and it crowbars at 90VAC and 140VAC. It has tripped even though I didn't see the lights change. I'd like to put it on a generator, to see if it works. I need to replace the impeller and get a Kohler running on my friend's boat, so I think I'll take it with me to test. I'll measure the line voltage and frequency, too.

If you really want to scare the hell out of yourself, take a scope and look at the waveform of the generator output as well as the UPS output. Electronics to make a UPS output a sine wave is pretty expensive and you might be dealing with almost a square wave, meaning if RMS is correct, then peak voltage will be low. And I'd expect the generator output to be dirty, too.

If you do this, be sure you first think of how to isolate the power from the scope so you don't have any lethal voltages where they can be touched.

edit: re These expensive automation systems are useless if the power goes out: Holy crap! I just realized my flashlight won't work if the batteries are dead! [clutches pearls] What EVER will I do?

During the last big outage in my area power was out for several days. Almost immediately after the lights went out a gasoline driven generator was hung on a utility pole at the edge of our property, under one of their amplifiers. The generator continued to run till power returned, then the generator disappeared as fast as it had appeared. I never saw any actual elves. I don't know if this was a Comcast or power utility accommodation. Unfortunately, we had FIOS, no battery deliveries, no cell tower, and no power to run things anyway.

Even those with a generator had trouble finding a gas station that could pump.

I have a boy power flashlight and emergency radio for use during grid failure. As long as I have calories, I'm good.

I always carry a 5 gallon can in my truck, have two 5 gallon cans in the outbuilding, and the generator has a full 5 gallon tank..

Generator runs for 24+ hours on a full 5 gallon tank, so I am good to go for most outages.

Couple times we were without power for more than 4 days, I was able to find a gas station that was up and running.


Worst case, I'll head to the beach house with the coolers full of the good stuff.

you beach people can survive on whiskey and salt water.... ;>)

Damn near.

It's wine, bikini clad babes and pray the wife doesn't see me lookin'... ;-)