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[Ronski]

I'm sure on both my UPS's I can adjust the voltages for when it switches, my home one is an APC Smart-UPS 1500, can't remember what the work is, but it's not APC.

[jelv]

Just checked the settings on my APC back-UPS CS350. The high voltage intervention can be set between 256V  and 278V, the low can be set between 196V and 160V. There's also a setting for noise sensitivity which can be set as high/medium/low.

[Alex Atkin UK]

That's bizarre, I was under the impression anything under 216 is considered a brown-out and there are no guarantees all hardware can handle it, thus the point of having a UPS.

A brownout happens when the voltage drops below the usual mains supply level.

Brownouts are damaging for IT loads – in many ways they can be more disruptive than a total blackout, when the power simply goes off. During a brownout, devices continue to receive power but at a reduced level. This can cause some devices to malfunction.

Uninterruptible power supplies can handle the reduction in voltage due to its input voltage window. When the voltage drops outside this window, the UPS’s batteries kick-in and take over without any disturbance to the load.

[PhilipD]

Hi

That's bizarre, I was under the impression anything under 216 is considered a brown-out and there are no guarantees all hardware can handle it, thus the point of having a UPS.

There is no hard and fast rule that dictates what a brownout voltage is.  Essentially a brownout just means a temporary dip in the voltage from what is the norm.  Check your IT power supplies, I expect most if not all will be switch mode power supplies and work internationally, so 100-240 volts rating.  If you want to argue anything under 216 volt is a brownout then that means all IT equipment running in countries with 110-120 volts (which have exactly the same power supplies just different pins) are all running in a constant brownout situation and so must be damaged very soon and fail, but clearly that isn't the case.

Most UPS's are designed purposely not to transfer over to battery power until somewhat lower or higher than the max and mins of the supply companies voltage specification, simply because it isn't necessary to maintain the AC voltage within that range with IT equipment (they can run down to at least 100 volts and still work fine), and this saves wear and tear on the battery and the circuitry by switching only when necessary.

You can get online UPS's that will essentially regenerate the AC voltage 24/7 and the output voltage never varies, however these are more expensive and less efficient, and overkill for consumer use.

What you need to understand is UPS's are designed to maintain the voltage in a range required by the attached equipment to continue to operate, not to maintain the grids AC voltage specification.  A UPS isn't feeding back into the national grid, it's feeding IT equipment and is designed for that purpose.

Also worth remembering that IT equipment doesn't work on 240 volts, it is usually 12 volts or considerably less, so receive far higher volts than they need, there is a huge buffer between what IT equipment needs to run and what they get fed, which is why AC adaptors can be rated for use as low as 100 volts, and in reality they will be designed to run with some tolerances on those ratings, so will work quite a bit below 100 volts even.  A brown out down to say 80 volts wouldn't cause a problem for most IT equipment.  We've probably all experienced a blip in the power supply where the lights have dimmed for a split second yet things like TVs and computers have carried on working without a hiccup, it is because they can run on lower voltages.

If you have a power cut does your IT equipment attached to your UPS continue working okay? 

Regards

Phil

[Alex Atkin UK]

Hi

There is no hard and fast rule that dictates what a brownout voltage is.  Essentially a brownout just means a temporary dip in the voltage from what is the norm.  Check your IT power supplies, I expect most if not all will be switch mode power supplies and work internationally, so 100-240 volts rating.  If you want to argue anything under 216 volt is a brownout then that means all IT equipment running in countries with 110-120 volts (which have exactly the same power supplies just different pins) are all running in a constant brownout situation and so must be damaged very soon and fail, but clearly that isn't the case.

Most UPS's are designed purposely not to transfer over to battery power until somewhat lower or higher than the max and mins of the supply companies voltage specification, simply because it isn't necessary to maintain the AC voltage within that range with IT equipment (they can run down to at least 100 volts and still work fine), and this saves wear and tear on the battery and the circuitry by switching only when necessary.

You can get online UPS's that will essentially regenerate the AC voltage 24/7 and the output voltage never varies, however these are more expensive and less efficient, and overkill for consumer use.

What you need to understand is UPS's are designed to maintain the voltage in a range required by the attached equipment to continue to operate, not to maintain the grids AC voltage specification.  A UPS isn't feeding back into the national grid, it's feeding IT equipment and is designed for that purpose.

Also worth remembering that IT equipment doesn't work on 240 volts, it is usually 12 volts or considerably less, so receive far higher volts than they need, there is a huge buffer between what IT equipment needs to run and what they get fed, which is why AC adaptors can be rated for use as low as 100 volts, and in reality they will be designed to run with some tolerances on those ratings, so will work quite a bit below 100 volts even.  A brown out down to say 80 volts wouldn't cause a problem for most IT equipment.  We've probably all experienced a blip in the power supply where the lights have dimmed for a split second yet things like TVs and computers have carried on working without a hiccup, it is because they can run on lower voltages.

If you have a power cut does your IT equipment attached to your UPS continue working okay? 

Regards

Phil

The argument isn't if the equipment will work fine, because yes I'm well aware it should do due to international PSUs.

The point is that the only guideline you have for what voltage range the equipment is designed to run at IS the grid voltage range for the country the UPS is sold in.  So logically it should be configured to stay within that range to be 100% sure all connected equipment is within spec.

Its rare to have power cuts around here so I haven't given it an extensive test, but I have switched it off at the socket a few times to prove it works.  The battery already seems to be a bit p00 though, drops to about half a charge the second its under load.

[PhilipD]

Hi

Sounds like it isn't a very good UPS anyway then, maybe a replacement should be on your priority list.

Regards

Phil

[Alex Atkin UK]

Maybe, but if it gives me a few minutes for the PC to shut down, its probably good enough.   I just got more paranoid after upgrading the server to 30TiB of space, didn't fancy all those drives dying at the same time at some point due to an avoidable glitch in the power.

Ironically, I'm probably more likely to accidentally hit the hair-trigger power button on the front of the UPS than have an actual power cut. 

[sevenlayermuddle]

A few years back, following restoration of power after a network fault, I noticed a few hours later it wasn’t quite fixed... low voltage, about 160-180V  iirc.

I noticed it because various appliances were unhappy.  My microwave oven, whilst fully responsive and lighting up, rotating the plates, and making all the usual beeps, failed to induce any heat whatsoever in its contents.   The fluorescent lights in the garage failed to start up, just flickering endlessly, failing to catch.   My IT equipment on the other hand was entirely happy, though I did disconnect my broadband for fear of associated bursts of interference, and DLM intervention.

Interestingly when I reported it, the power company were unaware but treated it with same if not more urgency as a full power cut.  I think the problem is that low voltage can become a safety hazard too as some appliances end up working harder to function at the low voltage, then overheat.  Fridge compressors for example may find themselves run continuously whereas at full voltage they get frequent rest breaks.

[roseway]

I had one of those experiences a few years back. It was cold, and my gas central heating tried to start up. There was enough power to open the gas valve, but not enough to fire the spark ignition, so unburnt gas poured out of the flue. I phoned UK Power Networks to explain the danger, and urged them to turn the power off completely until the fault was fixed, but they weren't interested and just repeated that I should turn my heating off (which I'd already done of course).

[Alex Atkin UK]

Crikey, that's bad.  I mean how many people are going to notice that happened?

[sevenlayermuddle]

Crikey, that's bad.  I mean how many people are going to notice that happened?

How many would even understand the concept.  In my case I did make an effort to spread the word to a few neighbours that voltage was dangerously low.   But the responses were along the lines of “Ours is ok, look, we’ve the TV on and it’s working fine.”

[jelv]

There was enough power to open the gas valve, but not enough to fire the spark ignition, so unburnt gas poured out of the flue.

That sounds like a faulty boiler. It should have detected that the gas had not lit and shut the gas off again after a short time (certainly less than a minute).

[roseway]

It possibly was. It was a very old boiler.

[displaced]

We’ve got the opposite problem - our mains goes as high as 263V for hours at a time occasionally. Normally it’s around the 250V level.

We used to get through incandescent and halogen bulbs like they were going out of fashion before we swapped to LEDs.  Cheaper PSUs tend to die early too.

Have reported it to UKPN and whilst they agreed it wasn’t right, they didn’t seem to want to do much about it!

[sevenlayermuddle]

We’ve got the opposite problem - our mains goes as high as 263V for hours at a time occasionally. Normally it’s around the 250V level.

We used to get through incandescent and halogen bulbs like they were going out of fashion before we swapped to LEDs.  Cheaper PSUs tend to die early too.

Have reported it to UKPN and whilst they agreed it wasn’t right, they didn’t seem to want to do much about it!

No experience of UKPN. I wonder if you just encountering an out-sourced call centre who's script does not extend to your enquiry?

I’d be inclined to keep a record of each conversation, and to tell them you are doing so.   Once you have a reasonable amount of evidence (two or three calls) you can invoke the organisation’s formal complaints process, which means it will get processed by somebody higher up the food chain within that company.  Chances are that person will, perhaps after installing a 24/7 monitor,  back you up and maybe even make a reasonable offer of compensation for damage caused.