Uninterruptible Power Supply question

If the power is that critical... run it on inverter(sine wave) full time and just keep the battery charged.

GordonThree wrote:
On many APC, at least the more expensive SmartUPS line, there's an adjustment on the back near the power cord accessible with a small screw driver that makes the unit more or less sensitive to "bad power"

those settings are in the software now for most of the apc/cyber stuff

On many APC, at least the more expensive SmartUPS line, there's an adjustment on the back near the power cord accessible with a small screw driver that makes the unit more or less sensitive to "bad power"

dryfly wrote:
Could one assume that all APC and CyberPower UPS's will in addition to providing battery backup, smooth the output A/C power? Reason I ask is that I'm in the process of installing a Generac whole house generator and while the specs look good, I still have some issue with the powering of some electronic gear. I'm just not sure if the Generac truly puts out pure sine wave voltage.

After installing Generac back up generator I had problems with 2 different models of APC UPS's. APC said it was the generator, the Generac dealer said it was APC! The generator installer did an upgrade designed to make the generator more compatible with some furnace electronics - it didn't help.

The UPS came on when the utility power dropped, but after the generator started it still insisted there was a fault, and ran the battery down. It never passed the generator power through...

i think he is saying
to consider carefully the choice of which UPS to use
that many will fail to operate or 'complain' when used with a generator

THE op asked a question regarding UPS operation

most users are saying, a UPS is NOT needed with a generator, and consumer grade maynot operate correctly when used with a generator

Gdetrailer wrote:


You should also understand that many UPS units will not and cannot work with a generator as a input source.

As far as running electronic equipment from a generator goes, should be perfectly fine for 99.9999999% of the equipment out there..

I understand, but this is a little confusing. Are you saying that it is necessary to remove the UPS when running on generator power? If the UPS may not perform on generator power, and yet the generator should supply smooth enough AC, it sounds like when generator is activated the UPS must be taken out of the circuit. What am I missing here??

Dutch_12078 wrote:

Gdetrailer wrote:

Pretty much ALL of the APC UPS versions are MSW, not sure about "Cyberpower" but I suspect they may also be MSW since they tend to be a lot cheaper than APC, if not they may be extremely cheaply built PSW and if that is the case I would take a APC over the Cyberpower.

APC has a number of pure sine wave models, mostly in the Smart-UPS series. The Smart-UPS 750VA (SMT750) is just one of them...

That is a PRO model marketed toward a server room which most folks would not buy since it is more expensive than most consumers would be willing to shell out.. Nor would most consumers find these in most retail stores.

That is why I mentioned "pretty much ALL APC versions are MSW".

Retail stores typically carry the lower end shoe box/power strip versions typically 450 VA.

Additionally the model you pointed out specifies "Output Frequency (sync to mains)
50/60Hz +/- 3 Hz" which IS why you are able to get it to operate with a generator.. MOST of the consumer UPS units typically will not be able to sync higher or lower than 60 hz properly.

Additionally APC states "Output Voltage Distortion
Less than 5% " which is NO BETTER than MOST GENERATORS..

From APC WEBSITE HERE

So, in the end, even a Sinewave APC UPS cannot provide any better sinewave than most generators since most generators also spec similar distortion specs!

The only real nice part of a UPS is to catch the in between time from when the power goes out to the point you get generator up and running.

Much less about "clean" power..

As far as sensitive electronics goes, SHOW ME SOME REAL LIFE EXAMPLES of these so called "sensitive to dirty power electronics"..

I have run pretty much anything I could get my hands on over the years and have not had any thing blow up or burn up or malfunction from MSW UPS units and or portable generators..

One would think that TVs, stereos, sat equipment and PCs are "sensitive", they are not, not even a little bit..

Modern day TVs, sat and PCs ALL use switching power supplies, those supplies rectify the line input to DC, then run that DC through a high frequency chopper the chopper output goes through a high frequency transformer, the output of the high frequency transformer is rectified and filtered to DC..

NOTHING in a switcher is "sensitive" to dirty power since the initial input stage is rectified to DC AND BRUTE FORCED "filtered" via a high voltage capacitor (typically 470 UF at 400V).. The chopper never sees any "dirty power".

Switching power supplies are not sensitive to frequency as they are designed to be used with 50hz - 60 hz. Pretty much nearly all switching power supplies now days are "universal" for input voltages, most are designed to operate from 100V AC to 250V AC.. Very few are for 120V only or 120/240 MANUAL switchable now days but even those had a wide range of voltage they can accept.

OP does not "need" UPS units to "clean" the generator power..

The only reason one would WANT a UPS would be to provide backup power until the generator has started and stabilized.

But OP does need to be aware, NOT ALL UPS UNITS will be able to sync to a generator and that is what I was getting at.

Gdetrailer wrote:

Pretty much ALL of the APC UPS versions are MSW, not sure about "Cyberpower" but I suspect they may also be MSW since they tend to be a lot cheaper than APC, if not they may be extremely cheaply built PSW and if that is the case I would take a APC over the Cyberpower.

APC has a number of pure sine wave models, mostly in the Smart-UPS series. The Smart-UPS 750VA (SMT750) is just one of them...

I have plenty of ups operating off generators, from cheap Cyberpower to high dollar Liebert. Of course the generators aren't low end Generac they're high end Cummins units. I used to buy very expensive ups for everything, now only mission critical gear runs off the double conversion pure sinewave type, everything else runs off the cheap MSW standby type. Haven't had any trouble with power supplies rejecting the MSW waveform. However the equipment is only on ups for 2 minutes while the Cummins spools up.

dryfly wrote:
Could one assume that all APC and CyberPower UPS's will in addition to providing battery backup, smooth the output A/C power? Reason I ask is that I'm in the process of installing a Generac whole house generator and while the specs look good, I still have some issue with the powering of some electronic gear. I'm just not sure if the Generac truly puts out pure sine wave voltage.

Pretty much ALL of the APC UPS versions are MSW, not sure about "Cyberpower" but I suspect they may also be MSW since they tend to be a lot cheaper than APC, if not they may be extremely cheaply built PSW and if that is the case I would take a APC over the Cyberpower.

You should also understand that many UPS units will not and cannot work with a generator as a input source.

UPS units are extremely sensitive to FREQUENCY of the input. Units designed for use with US 60hz grid are looking for 60hz, not 59 hz or 61 hz like a generator will supply. Very few UPS units will work with a generator as a input.

As far as running electronic equipment from a generator goes, should be perfectly fine for 99.9999999% of the equipment out there..

Not sure as to what you feel is "sensitive" electronic equipment but I have run TVs, stereos (EXPENSIVE ONES NOT THE $100 types), Satt receivers, COMPUTERS, home fridges, power tools and so on from MSW inverters..

Truth be known, very few electronic devices are "sensitive" to "dirty power" and the disclaimers are used by pretty much every generator manufacturer warning folks to not use with "sensitive" equipment is nothing more than a CYA for the manufacturer.

Your Generac WILL supply a CLEANER SINE WAVE than any MSW UPS. Non inverter generators by there nature produce sine waves, that is where the grid (shore power) gets their sine waves.

The only thing about portable and home standalone gens is they may have some waveform distortion, typically 10% or less but that IS far less distortion than a MSW inverter or MSW UPS.