Uninterruptible Power Supplies

[TTbangbang]

Hello all,

We have been given a couple of big office UPSs. I hate the things but the IT wizard in the household thinks they're a good idea. Is there any way I can say they are unsafe to have on ] whilst I'm working on the de-energised electrics? Pray

 

[ian932]

Not sure if I understood the question - are you working on the circuits fed by the UPS ?

 

[septiclecky]

?:| ? :|

Hello all,We have been given a couple of big office UPSs. I hate the things but the IT wizard in the household thinks they're a good idea. Is there any way I can say they are unsafe to have on ] whilst I'm working on the de-energised electrics? Pray

How can they be unsafe to have on whilst working on a de-energised electrics? ?:| ? :|

It can only be unsafe if you have isolated the supply to the UPS but have not isolated the output from the UPS.

Once the output from the UPS is isolated then it is safe to work on the circuits supplied via the UPS.

 

[TTbangbang]

Thanks for the responses guys.

I was referring to UPS supplying one/two computers, which would kick in if the power goes. So, as I understand from septiclecky, UPS would be of no use if the electrician is in the house working on the computer circuit - as the computers would have to be disconnected from the UPS too.

So... I could put the argument (against having UPS) that if a fault occurred that tripped the RCD protecting the computer circuit amongst others, then the UPS have to be disconnected too. So basically they're worthless!

Yee hah!

I mean, how likely are lightning strikes and surge currents in this country?

 

[ian932]

I mean, how likely are lightning strikes and surge currents in this country?

UPS is not primarly for the above its to stop data loss during power outs or to give the user time to save/backup. If your user wants UPS I dont see the problem his money and I cant see why it make your job harder. Only thing I would advice is that sockets are red ones so sparks know they may be live after Main switch is turned off

 

[TTbangbang]

That's a good idea re. red socket outlets.

... can easily get curtains to match

 

[bassman]

Confusing

If the computers are powered via the UPS surely they carry on when power is turned of.I have sites that are tested monthly for this reason to make sure that the UPS keeps the computers running. Only the computers no screens or printers.

Depends on what type of UPS as the newer models APC type have audible to let some one know that they have gone to inverter.

If it is only small units usually fed via kettle lead unplug lead before doing maintenance and wait till power restored before plugging back in.They are suppressed for transients, but not woth the risk.There is also a lead to put between PC and UPS which you can program for pc to shutdown and save any info, very rarely used.

 

[Pyro]

I mean, how likely are lightning strikes and surge currents in this country?

Re: lightning strikes:

Rural West Yorkshire July/August 2006.

If anyone on the forum has had the pleasure (or otherwise) of being in southern Africa in the rainy season you will know the meaning of the term "thunderstorm".

There was such a storm in West Yorkshire / Lancashire one Sunday afternoon in 2006. It had the force to rival a good African thunderstorm. Lightning strikes in the Hebden Bridge area were seriously impressive to watch and listen to.

Re: surge currents.

It's not only surge currents that damage computers (and other electronic equipment) but also brown-outs and intermittent interruptions.... The intermittents are probably the worst for causing damage.

Again, rural West Yorkshire features and it gets its unfair share of these. A client on a small trading estate has an electronics business and has his PCB assembly machine fed from a 3kVA UPS. He also has UPS units for the computers, workbench equipment and fancy test kit. There is no telling what damage could have been caused by brownouts & intermittent power failures, but the UPS units have ensured that the resultant losses have not occurred.

Final point about power outages - the landlord of the above noted trading estate has installed a back-up generator to provide cover during extended power outages.

Pyro.

 

[TTbangbang]

Pyro,

Thanks for the enlightenment

Haven't experienced a ripping good thunderstorm for a while (am in Cambridgeshire), but best one ever was in Northern Territory, Australia - bejasus!

 

[ABC Technical]

I miss the really big thunder storms we used to have when I was a kid.

 

[Mr Smith]

i too remember those , abc .

have not seen anything similar in a long time .

other than africa, as ttbang says.