Site voltage at 250V

[psydii]

Anyone have any experience with getting to the bottom of a site supply being over voltage? Our UPS’s are in a warning state, and we’ve had one computer PSU pop this morning (though that could be coincidence).

[psydii]

Anyone have any experience with getting to the bottom of a site supply being over voltage? Our UPS’s are in a warning state, and we’ve had one computer PSU pop this morning (though that could be coincidence).

 

Update: The limits are 6% below, but 10% over, so 250V is still within spec.

 

https://www.legislation.gov.uk/uksi/2002/2665/regulation/27/made

 

But still interested to here how other have dealt with power problems.

[IrritableTech]

My UPS errored on frequency out of range earlier this week. First time I'd seen that.

Zabbix showed it was resolved after ten minutes.

 

In winter the voltage tends to be higher, perhaps the warmer weather has caused this normal adjustment to be higher than planned?

[john]

Are your ups not smoothing that out to give stable 230 or 240 out?

 

If you frequently have spikey power your electric DNO maybe will consider putting loghers on the incoming supply to see but as was pointed out its within the tolerance so kit should be fine with it.

[psydii]

Are your ups not smoothing that out to give stable 230 or 240 out?

 

 

 

UPS's handling it fine. But they are complaining, and I don't recall seeing an over voltage incident lasting more than a few minutes in the last 20 years, so it's piqued my interest.

 

If you frequently have spikey power your electric DNO maybe will consider putting loghers on the incoming supply to see but as was pointed out its within the tolerance so kit should be fine with it.

 

DNO? Logger? What are these? Supply and troubleshooting of the big plant stuff isn't the forte of the teams I currently have access to.

[HPlum78]

Trying to prove that there is a constant over voltage to a supplier is like pushing water up hill... how old is your building?

[dapaulio]

Supported a school whose electric in one building supplied 250v and as a result the UPS dealt with it but at the cost of its life span. It killed two ups in 2 years.

I produced ups logs showing the over voltage and how the ups was behaving.

Hope this helps

[Andrew_C]

DNO - your actual supplier, not necessarily who you get bills from. A "disturbance logger" is fitted by DNO and is left for a period of time. Any fluctuations are recorded, and if out of spec, can be remedied. It is possible your voltage has gone up if a major user in your area has shut down. If so, the DNO might change the transformer at the substation to drop your voltage. But probably not if you are only running at 250V.

[MrEprise]

After a spate of PSUs in one model of PC* going bang, I started doing some investigation and found in many cases more than 250V being served from sockets (I think the record was 257V from one socket I tested!) When we contacted Western Power Distribution about it, they were happy to argue that 250V was perfectly acceptable (while also mentioning that rural areas always get the higher volts for some reason) but then after repeated phone calls (where we kept telling them that the voltages were a lot higher than normal and that it was destroying computer equipment) they eventually backed down and sent someone out to adjust the delivered voltage from the substation. Since then, we stopped getting fireworks in computer rooms and the lower voltage AFAIK didn't have any detrimental effect on anything else.

 

*These were HP d530 desktops. It didn't help in the first place that the glue holding various components in place in the PSU could become conductive if moisture from the air is also introduced to the glue - usually those in damp rooms, without then introducing a higher voltage that the PSUs seemingly couldn't cope with.

[Chris_Cook]

When it comes to power circuits, 10% variations shouldn't be a problem. Equipment should easily be able to handle that if its been designed properly. So anything under 253v is fine. If equipment can't handle this then its a warranty issue for the manufacturer.

 

Some UPSs can be very sensitive, so its worth tweaking the sensitivity to match the normal site conditions over time. If your voltage is normally around 250, then I wouldn't worry, but if its normally 230 and suddenly changes to 250+, then it might be worth investigating. What you don't want is the UPS going into protection unnecessarily, you just want a warning if the voltage or frequency changes. That would shorten the life of it or its batteries every time it goes into protection. Its worth having a discussion with your UPS manufacturer about the recommended settings.

 

The voltage will be dependant on the distance from your substation - the closer you are the higher the voltage will be. That's because the voltage will drop over the length of the cable.

 

Also, remember that the UK voltage was 240v before the EU standardised in 1990. The 230v + 10% bit was so that we didn't have to change things. Or at least that's the story I was told. So your only really 10v over what the DNOs are aiming at.

 

Surges and surge protection is a different thing, and worth investing in. I think you can even get that installed at the distribution boards these days.

 

The other thing that can shorten the life of PSUs is if the outputs are overloaded. We've found this with some cheaper PCs and PSUs where they specify a big number overall, but then one voltage rail can't keep up. I ended up checking this with the PSU and mainboard manuals and then complained to the manufacturer.

[psydii]

Trying to prove that there is a constant over voltage to a supplier is like pushing water up hill... how old is your building?

 

Power supply and distribution is all less than 15 years old. It was a sudden change (in so far as we'd occasionally have under-voltage events, but never sustained, and we've never had an 'over-voltage' event before). It is ongoing; three days later we are still at 250V.

 

Several of our UPS are about the same age as the building supply and distribution. Several are a lot younger. We are pretty used to what constitutes 'normal' for the site. However we've been up to 253.70V over the weekend. I'll ask around and maybe escalate to the LA's Facilities team.