Where to start diagnosing high voltage spikes?

[von555]

The electrician wasn't here because of the voltage problems, but to install 2 new plug sockets. It was only after he'd gone that I worked out that the UPS was maybe not faulty. I don't really blame him for not noticing this problem. Who knows how long it's been like this? My old UPS (which I had for about 2 years) didn't shut off with high voltage spikes, just outages.

 

[ricicle]

I'm going to go with a bad neutral/earth connection somewhere at the Tx star point ! Other consumers may also be affected but haven't got any form of voltage measurement to pick it up. Their electronic equipment might start failing soon.

 

[JohnW2]

f those figures are correct, then the chances of someone putting a meter on it and find a voltage <253V (and therefore declare that "the supply looks fine") are pretty low.

Which suggests to me that the electrician may never have actually checked that! (nor, I suspect, did he check the ELI which may be a bit on the high side)

Exactly.

Kind Regards, John

 

[JohnW2]

My old UPS (which I had for about 2 years) didn't shut off with high voltage spikes, just outages.

That clearly sounds as if it was a totally different issue.

Kind Regards, John

 

[JohnW2]

I'm going to go with a bad neutral/earth connection somewhere at the Tx star point !

That would make sense, although I would be more than a little surprised if digging up the OP's drive was the first thing they would do to investigate that!

Kind Regards, John

 

[von555]

My old UPS (which I had for about 2 years) didn't shut off with high voltage spikes, just outages.

That clearly sounds as if it was a totally different issue.

Kind Regards, John

No issue. I had a UPS for two years, that worked fine. But it didn't switch to battery (and then shutdown when battery was exhausted) on high input voltage. When that UPS died (about a month ago) I purchased the first APC UPS. After testing it for 3 weeks I assumed it was faulty. Got a new one this week, same behaviour, and now they're digging up the drive.

My power is likely to go very soon. Hopefully there is an improvement when it's back up...

And just for fun:

Untitled

• von555
• 6 Dec 2012
• 1

 

[rjm2k]

Are you on a 3 phase supply?

Suspect it's something to do with these....

http://en.wikipedia.org/wiki/Ferranti_effect

http://en.wikipedia.org/wiki/Characteristic_impedance

Could there be one of these under the drive?

http://en.wikipedia.org/wiki/Line_reactor

 

[JohnW2]

No issue. I had a UPS for two years, that worked fine. But it didn't switch to battery (and then shutdown when battery was exhausted) on high input voltage. When that UPS died (about a month ago) I purchased the first APC UPS. After testing it for 3 weeks I assumed it was faulty. Got a new one this week, same behaviour...

Oh, sorry, I didn't realise you were talking about a third UPS. Do I take it that the first APC one behaved in the same way as the second ('current') one?

Kind Regards, John

 

[von555]

Power back. Dunno for how long. I have already said (though the thread is getting long), that the first APC UPS and second replacement one both acted the same. I thought the first one was faulty so returned it, and was surprised when the second one behaved in exactly the same way. I'm going to check voltages...

 

[von555]

Are you on a 3 phase supply?

Suspect it's something to do with these....

http://en.wikipedia.org/wiki/Ferranti_effect

http://en.wikipedia.org/wiki/Characteristic_impedance

Could there be one of these under the drive?

http://en.wikipedia.org/wiki/Line_reactor[/QUOTE]

No idea...

Just out of curiosity, what is the next step if nothing changes? Should I expect to see my line voltage come down to 230-240? Doesn't look much different at the moment....

 

[EFLImpudence]

Are the engineers not talking to you?

 

[rjm2k]

Are the engineers not talking to you?

and are you not peering into the hole they are digging in your drive? I would be!

 

[rjm2k]

[duplicate deleted]

 

[von555]

Ha. Even if they did I might not understand. I was just wondering... As it happens the electricity went off again and has come back and it seems a bit more stable. Between 246-256. Obviously it hasn't been long.

I'll obviously ask them about it....

It is freezing cold and soaking wet. I'll leave em to it...

 

[JohnW2]

Just out of curiosity, what is the next step if nothing changes? Should I expect to see my line voltage come down to 230-240?

As others have said, 'they' are the people to ask about that. The voltage may not necessarily come down that far. My supply is rarely below about 244V (never seen it below 240V), but I've never seen it above 250V. As westie has explained, the rules require that it does not go over 253V (for 95% of the time!).

Kind Regards, John