UK voltage

[JohnW2]

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.

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]

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.

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...

 

[JohnW2]

... 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...

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

 

[SUNRAY]

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

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.