UK voltage

bernardgreen said:

The infinite monkey theorem states that a monkey hitting keys at random on a typewriter keyboard for an infinite amount of time will almost surely type any given text, such as the complete works of William Shakespeare.

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Indeed.

I'm not sure how much, if any, truth there was in it, but there was a story around a few years ago of the staff at some zoo having become intrigued by that oft-quoted attempt to explain 'random'. The story was that they provided their group of chimpanzees with keyboards, and got them used to pressing the keys (and, I imagine, seeing something happen as a result). However, the story went on, they gave up after a few months, since none of the animals had by then succeeded in producing even the first word or two of the first of the works of Shakespeare ...

... which, I suppose, all goes to remind us how large a number 'infinity' represents

Kind Regards, John

SUNRAY said:

I was out on a call yesterday evening, customer complaining things failing.
voltage measured variously between 235v and 245v L-N. Sadly 410v N-E, 630v L-E and unstable 200v to 350v E- earthspike.
DNO came quickly and pulled tails and bonds. Generator provided today for about 10 properties.

At home now 235.7v, a few years back it would have been 250v to 255v as I'm very near the sub.

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A colleague was back round there today as network engineers were reinstating supplies, It seems these properties are fed by a 400 to 230v transformer across 2 phases and a contact between primary wiring and secondary neutral/earth was being blamed. The figures don't add up for me but hey ho...

SUNRAY said:

... It seems these properties are fed by a 400 to 230v transformer across 2 phases and a contact between primary wiring and secondary neutral/earth was being blamed. The figures don't add up for me but hey ho...

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As you say, there seems to be an arithmetical problem there, since I don't really see how one can get 630V L-E out of what they are suggesting!

Kind Regards, John

JohnW2 said:

As you say, there seems to be an arithmetical problem there, since I don't really see how one can get 630V L-E out of what they are suggesting!

Kind Regards, John

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Well the numbers are there but I too struggle to see what fault(s) combined to give my test figures.
The best I've come up with is a 3ph transformer off the HV network with no earth on the star and an earth fault on the 'unused phase 3' or even on ph1 shown in red [I suppose it could have gone unoticed like it for a while if nothing else is connected between the transformers] and the broken earth & neutral/primary contact fault shown in purple:

But I'm grasping at straws and it doesn't explain the 200-350v found between the earth and spike.