Cause of frequent power interruptions: "livestock rubbing themselves against poles causing [circuit breakers] to operate" ;-)

Oct 05, 2022 Last reply: 3 years ago 33 Replies

If you can find someone who has recently had some electrical supply work done then they may have a map of your local distribution grid. Worth finding a copy (or talk to your local PC they may have one).

That is much more likely - they haven't done preventative tree maintenance here since they took over from NEDL (who did it every 2 years). One of our failures was a tree fell onto a major line, the other was a pole thinned to 3" that snapped at cow rubbing height.

I agree that we have had more than our fair share of outages this autumn. It wasn't such a problem in the past. They seem to coincide with high rainfall where I am which could be weighing down tree branches.

We used to have 240 volts on three vertically arranged once insulated with fabric and rubber lines. The rubber had long since perished and strips would hang down between the lines. In the wind and wet they would arc and spark spectacularly dropping bits of burning rubber onto the ground. It would dim the lights sometimes but arcs never persisted for long enough to trip out a higher level breaker.

Also ask farmers if they have the power grid distribution map for their property. I suspect if you stay off when others are reconnected it is usually because the hard fault is on your patch.

We have mapped our entire zone and know where all the substations, transformers, switched and breakers are for next time.

There are usually two at least where we are. Here there is full 3 phase running N-S on bigger poles that have a t shape at the top ie. . _|_. | |

And spurs off that that just have the two lines. I hadn't realised that my part of the village only had two phases until we investigated exactly what was going on during the long storm Arwen power cut.

Yeah, special transformer on each pole to transfer 33 kV down to a level that cows can feel but which will not fry them. ;-)

If there are only two HV wires on the poles then you cannot get 3 phases down them.

Are there any single phase+neutral HV lines anywhere ?

No s*it Sherlock!

I wouldn't have though so.

They typically operate balanced transformers across a phase pair at HT rotating the ones they use to feed each successive village. The output at mains voltage is +V 0 -V one three lines one of them neutral.

Life gets interesting if just a single phase goes down. So few modern gadgets even notice but the kettle takes forever to boil!

If not frying them is a requirement, then the fence could probably be powered by induction.

To me, an HV line on wooden poles carrying just two wires is immediately obvious, because mostly the cross country poles carry three wires. Had you never ventured to that part of the village ?.

There are a couple of isolated houses along my walking route fed by a 2-wire HV arrangment and a single transformer on the pole which seems to be connected to both HV lines (which is odd if 1 phase plus neutral makes 230V). The output from the tranny is just a pair of wires going to both houses, where one connects across to the second house.

You have no idea quickly fencer lead acid batteries learn to walk. They must feel isolated and alone out there in the countryside:-)

We have just that arrangement here, except it's 5 houses.

We don't allow ourcattle to ride on trains anymore, they go in f****ng great B double or triple trucks. No point in sending you a photo.

Do you need a battery when there is a power line at the top of the pole? I would have thought it would be possible to tap off power with an induction pickup and, if it is something the electricity supplier is doing to protect their poles, that wouldn't be stealing electricity.

If you have a decent list of when the power trips have happened, you should be able to compare that with the historical met records and see if they correlate with times of higher than normal wind.

I have compared my list of power cuts with wind speed details from my own weather station and I can't see any correlation for most of the interruptions. There are a very small number that correspond with gales and thunderstorms, which I discount as being "act of god". The rest occur at random times when the weather has been unexceptional.

NY snipped-for-privacy@privacy.invalid wrote

How reliable is your weather station wind speed data tho ?

That's one thing which is very difficult to measure reliably because it varys so much locally due to houses etc. It might be interesting to compare your wind data with the official data.

And even more complicated, maybe the wind only matters when it is at right angles to the line of the power poles.

And the other possibility is time of day. Do cattle rub against poles in the night ?

Here they are mostly associated with driving rain/snow and high winds.

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