UPS and Generators

UPS units can be frequency sensitive but when I tested mine I hooked a meter to it, Voltage and Frequency were both good on the true RMS meter. but I am guessing waveform.. The Genrac 1000 has a rating of 3% THD or less on the waveform, but ... there are components that help to shape that wave, and some of them can "Age" if allowed to set too long... They tend to dry out or something (We talk about them drying thought that may not be what happens). once you work the genny a while they shape up and work properly.

This is a real problem for vintage radio lovers cause if i were to plug in say an Eico 720 (My first Novice Radio Transmitter) I would want to use a Variac to bring the voltage up SLOWLY to insure I did not blow those very same parts in the transmitter. (yes, since it produces a waveform)

http://twit.tv/hn and I think it is the last program (Dec 9 2014) one of the hosts fires up HIS Eico 720 Nice rig, His was set up for AM though, mine only morse code

For just a DVR in the RV consider a small sine wave inverter to run it full time when not plugged in.

I had problems with my UPS at home when it was powered by a 15K Generac back up generator. The installers did an upgrade to the generator that is required for many high efficiency furnaces hoping it would solve the problem, however it didn't. With the generator supplying power, the UPS would not switch to it, would run down the battery, then die. Short blackouts were OK, but anything over half an hour made it useless. I talked with APC & they stated the generator produced "dirty" power that the UPS rejected. I never did come up with a solution.

yea, but i have cyberpower units as well, and they don't allow the change. at least not the models i own

i did not try to change the apc units yet, but it will prolly work

You could try loosening the transfer point on voltage on the UPS- I know my low end APC models let you set transfer voltage (high and low), but not frequency.

smkettner wrote:

LittleBill wrote:
i did a test recently for my stick house with a new generator. all 4 of my UPS's failed the test, by constantly switching between power and battery.

Are you sure it was a UPS fail vs generator fail?

well they kept switching. which apparently if the generator doesn't keep within a .5 hertz variance, they won't work

i have scoped and checked alot of generators. this is by far the most stable one i have used


normal no load you need to be up near 130v so by the time you get to full load your about 117-118.

this generator sits around 123-120 from 500 watts too 7000 watts.

i was impressed with it, but not my ups's

Many portable generators are kind of nasty,, The INverter ones should be clean but the traditional generators, epically the contractor models, can be nasty.

I used to have a 1,000 Genrac Portable (Hard to find, you usually find a 900, but 1000 is the smallest I can use) when it was new, it had been sitting in a box for lord knows how long, and an APC UPS would complain about it.

After I had run a tank of gas trough it, mostly running light bulbs (Big ones) it settled down and the API was happy with it . It was just big enough to charge the batteries on this house.

LittleBill wrote:
i did a test recently for my stick house with a new generator. all 4 of my UPS's failed the test, by constantly switching between power and battery.

Are you sure it was a UPS fail vs generator fail?

the problem with UPS is frequency sensitivity
they are designed for use with incoming Utility power
which may vary in voltage..but Almost never varies in frequency

I suggest bypassing the UPS when on generator power for home use
when there is a power outage,

with out building your own battery & inverter setup
i doubt you will find a 'cure' for your UPS problem , with out spending more $$ for "line conditioning" of incoming power..whether generator or utility

what type of generator were you using? any idea on the frequency or voltage or sine wave pattern?

what model ups's?