| The Breakroom > The Water Cooler |
| Too Many Volts |
| (1/6) > >> |
| awemawson:
When we moved here eight years ago, I was aware that the mains voltage was quite high. Not really surprising, as we are supplied overhead by an 11kV three phase line, and the step down transformer to 415v three phase / 240v single phase is on our land. This means that we are at the feed end of the cable, so if they are to allow for voltage drop to premises at the far end, we will inevitably be at the high end. Indeed, my barn / workshop is a direct cable from the transformer pole, and the farm house is 'one pole further downline', and typically there is a one volt difference in the mains between the two. In the picture, the cable going to the left feeds only my barn / workshop, and the cable going right feeds the house then onwards to our neighbours half a mile away, and a small industrial estate. |
| awemawson:
Now we've had problems with rather a lot of bulbs blowing, especially LED GU10's , but when I've measured the mains it's always been within the legal specification of 253 max. However, when I fitted UPS's to the PC's, they continually monitor the voltage, and were giving me high voltage alarms. Plotting out the recorded data it was obvious that when the load was low 'down line' at night, in fact the volts were going as high as 256 and once 257. I reported high voltage, and a 'UK Power Networks' man came out, measured, said it was in spec but on the high side, and although he couldn't act on my figures agreed to fit a voltage recorder for a week to see using their own calibrated instruments. Sure enough his measurements exactly traced mine, so he went out to the transformer and inspected the 'tapping switch', which was set to the highest voltage. That's wrong he says, they should always be 'one tap down' or even more - I'll get it altered. That was in early July. Since then we had a further five visits by various bits of the organisation 'just checking' resulting eventually in a notice through the door advising of a 'scheduled power cut' for today (8th December). Hooray - at last - about time. So 09:30 this morning a large Unimog access platform, and two vans arrived. First thing to do was set out a matrix of earth stakes and earth the Unimog, that had churned it's way into our goose field. Then they pulled the LV (415v) 200 amp fuses on the transformer pole. Then they had to 'mark the pole' to stop anyone else re-fusing |
| appletree:
You can get a box of tricks which attenuate the supply voltage and thus reduce the current drawn, might be worth it on the 240 house supply, I can imagine your volts are all over the place, also if there are Solar panels on that feed they can impact. When I was an Instrument apprentice my mate was in the electrical section his boss went to great lengths with power factor correction |
| pete3000:
Technically should be 230v/400v the old standard was 240v/415v. Sounds like someone has done their tapping wrong...... as you have found out. Didn't you measure the 11kv to see if it was in spec :zap: lol |
| awemawson:
Next they chopped out a section of the feed cables from each phase of the 11kV overhead line down to the transformer - all done live using long fibreglass tools and rubber gloves. Two man job, with one cutting the cable and the second grabbing the cut off bit to stop it falling onto the transformer |
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