PC Restart Problem During Changing-Over of UPS

Don't put resistive loads on them either. That means Laser printers (fuser) and floor heaters. I see both all the time and it's no mystery the UPS can't handle it!

Lol, yes I've seen under-desk heater plugged into the UPS, then people wonder why in only lasts a minute or two! I once saw a 1500W heater plugged into a 500W UPS, it was as if the UPS wasn't even there.

Yes Laser printers.

I have seen special notes for Laser printers in the UPS Catalogues whether it can handle or not.

The bios of some motherboards have a feature which will restart the system after a power outage. This is probably what is happening to yours.

To expand the thought just a little, some people want their computers to restart after a power outage. So here's how to do it, if your computer doesn't have the bios feature. (This was posted on Tom's Hardware by Chris Priede) There is no sense restating something clearly detailed.

You can make it "always on" by grounding the pin 14 of the ATX power supply. The wire going to pin 14 is usually green. Cut it a couple inches from the motherboard's
power connector (so that it can be reconnected if needed). Strip off some
insulation from one the (usually black) wires going to the adjacent pins 13,
15 - 17 without severing the wire itself; connect the power supply end of
the green wire to it. Leave the motherboard end of the green wire open.

I'm wondering if it could be frequency related. Just suppose that the frequency changes, will the UPS behave?

I'd call the manufacturer. You could also rent a power line disturbance monitor and find out what really happens when the utility goes down. You could also have regeneration within your plant or subsystem from motors continuing to spin.

You could try cutting power to the building.

Regard.

Answer in post #1 seems more logical as the behaviour of UPS on manual-switching is OK but on disturbance in power line can not be handled on Blackouts by UPS as one of the reason given in post #2; i.e. brown-out before black-out.

And I add that jerks/spikes in power line are a major cause of power failures due to heavy inductive load changes causing hi-surges/spikes.

You did not mention this problem is there since beginning of UPS installation or this problem started over a period of time?

1. If there is a switch on your UPS back side to select Inverter/ UPS modes change the switch to UPS mode. May it is in inverter mode. Then you will start hear a beep sound at regular time intervals.
   
2. Open your ATX SMPS if you know electronics, check big electrolytic capacitors. Replace if faulty (low micro-farads) or increase capacity by 20%.
3. Change small changeover relay in your UPS.
   

What model \ brand UPS is it??

Some of the cheaper line-reactive units do Not switch quickly enough <0.1s.

If this is the case, the PC will actually lose power and re-boot.

Regards,
Sapper

I think the root of the problem is the fan. If it is taken off and the problem goes away, then we know for certain. However, powering an inductive load and a computer on a UPS is not a good idea for reasons already stated.

Not going to disagree with you, while I think it (the fan) is the most likely cause, I wont discount battery age and condition or the type of UPS he/she is using either.

If it has been working previously and is only now exhibiting the issue described above, other issues could be coming into play.

However, if it is a brand new UPS, then the fan is likely the only cause.

Those small UPSs are only really designed to support a PC and Monitor or two long enough to shutdown cleanly.

They should not have heaters, fans, toasters or fishtanks on them... and I've seen all of the above in an office.

My personal favourite is the woman who tried several times to put an electric blanket over her chair to keep warm "cause the AirCon was too cold".

Regards,
Sapper

Gentlemen,

While I greatly respect all of your thoughts and wisdom and I know many things cause a computer to act strangely, there is still one thing I do know. A computer will not restart on it's own after a power loss, unless it is enabled in the bios or it's rewired to cause it to restart..

Now, the OP's situation is strange and weird as to what's happening and how it happens but we still can not ignore the bios. OR, perhaps he has a intermittant situation in his connections/ wiring to cause the effect I described in my previous post.

Randyl,

The software that comes with many of the UPSs available have options to restart your machine once the power has returned either WOL or Serial\USB.

If the drivers are installed it can be done. My servers\PCs are all set-up to restart once the power is back & the battery reaches 20% capacity. The UPS also shuts down and restarts each day to cover business hours.

It does depend on how the system is setup and how old the equipment involved is, but the capability has been around for a while.

Regards,
Sapper

Sapper,

You're right! It's been a few years since I retired. I must be getting a little old and fuzzy.

Randy

Thanks to all participants.

I have understood that the problem is "brown out before black out" not the that the fan is also running on single UPS with PC. If fan is also a problem then when i switch off the incoming mains to UPS, PC should also restart but not. It re-starts when utility goes out.

Maybe. However, you can isolate the problem by taking the fan off the uPS and see if the problem remains or goes away.

If the problem remains, then the issue is with the UPS. Call the UPS manufacture tech support.

If the problem goes away, then you know that the UPS can not drive the inductive load, which is a bad idea as stated before.

When the UPS kicks in there will most likely be a phase shift between the mains AC ad the inverter's AC phase. This can (depending on the phase shift) result in a large back-EMF pulse into the UPS. Not only does this stress the UPS, it will spike at the PC's power supply.

Even if the fan is not the direct cause it still is a bad idea to run the fan from the UPS.

Regards

Well gentleman please read the post once again.

The complaint is not that PC does not restart but it SHUTs DOWN on Power-outings of a typical condition, while it is running on UPS.

Otherwise you have a valid point for otherwise restart problem.

I popped in a GA with this.

The OP needs to undertake a systematic approach to the problem.

The Fan most of us agree should not be on the UPS and is the most likely culprit.

So eliminate the most obvious problem, the fan, then possibly the light as it is extraneous and probably does not need UPS support.

If the issue still present, then it is a UPS related issue, if it is no longer an issue, then the fan is the root cause and the issue is identified.
I can't say resolved as I can't be sure the fan wont be plugged back in.

Regards,
Sapper.

I have checked that even if i remove the fan from UPS, problem doesn't solve. I need to calibrate the UPS to switch on inverter if mains voltage drops at near about 195VAC. I think (not sure) UPS inverter enables at 170V which is the caused by PC to restart.

I am still confused why utility supply first "browns out" then black out. What i understand, when 11KV switches off, the large connected "inductive load" caused an "inductive kick back" which then caused a "brown out" before black out. The charged high tention lines may also be caused by this brown out. Am i right or just a cloddish thought?

If you are getting a lot of these power fluctuations, as well as changing the settings on the UPS to protect yourself.

You need to contact the utility company, because someone on the LV side of the transformer is pulling more power than the Transformer can support, thus the transformer protection is acting to protect the transformer.

As Current Increases, Voltage at the supply will drop, until the overcurrent protection kicks in and causes your voltage drop (Brown out) followed by Breaker Opens (Power Fail) seen at the UPS.

So first protect you system, Change the UPS trigger to 195V AC.
Second, Call the utility and put in a complaint or service request.

Regards,
Sapper.

Regards:

<.. decay due to the grid itself acting as a momentary "battery".>

Yes!

I remember a project "How to Store Inductive Energy" or some thing like it in I think 1960s where the purpose was not to loose power on <½ Cycle power outage for critical loads.

Regards.

In Lahore. How frequent the intruptions? I know the situation there.

See if some Welding shop is in your vicinity.

Arc welding generatates very dangerous spikes and brown-outs; locally assembled UPS are not capable of.

Even sophiscated design may kneel before the local power outages and disturbances.

Wow, what a concept. Welcome to the Third World. Not everybody has the benefit of a strong grid.

I wonder if this situation could be helped by the large capacitor 'power conditioners'? Maybe not for the whole building, but just the sensitive equipment. My larger UPS units have nice big caps, I imagine that is what they are doing, compensating for/absorbing spikes.