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Why does high wind cause power cuts?

Andy Millar
May sound like a stupid question but then "there's no such thing as...". Is it typically because the phases in a three phase line touch? Or because branches blow into the lines and arc across? Or sometimes one thing, sometimes another?


Google let me down, so posting this - in one of those brief intervals when we do have power today :) It's the fact that what ever is causing them is obviously easily resettable - by the rate ours has been going on and off today - that made me start thinking about it. (It's on the HV lines affecting my village and half the adjacent small town. But not, you'll all be relieved to hear, the Ginsters' pasty factory which is on the other side of town :D ) 


Thanks,


Andy
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    When  it goes out but then comes back after a second or so the auto-reclosers are reconnecting you. The fault is then either something transient,  which may be as simple as vegetation falling on the lines or wind blowing the rain into the wrong places on very wet insulators, or there is a hard fault that is not reconnected but there is at least one more dis-connector  between you and it that has locked off.


    This wikipedia article  has a US centric bias, but broadly similar devices are found on our  rural11kV lines, either staying off after a fixed no. of re-tries in a pre-set period or less commonly having a remote signaling link to tell it to go for a  re-try.

    Note that in the UK the 11kV does not distribute neutral, so we have current transformers looking for imbalance, that perform the equivalent of a coarse RCD on the 11kV outbound, so a tree against a line is easily detected. This is 'SEF' - sensitive earth fault tripping. You'd expect SEF trip and re-try to be more common than line to line or line down faults , which would be likely to be flash and a permanent off.


    This doc from ENW  explains a typical UK policy -  you may find section 7,4 a good read.

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  • 0
    When  it goes out but then comes back after a second or so the auto-reclosers are reconnecting you. The fault is then either something transient,  which may be as simple as vegetation falling on the lines or wind blowing the rain into the wrong places on very wet insulators, or there is a hard fault that is not reconnected but there is at least one more dis-connector  between you and it that has locked off.


    This wikipedia article  has a US centric bias, but broadly similar devices are found on our  rural11kV lines, either staying off after a fixed no. of re-tries in a pre-set period or less commonly having a remote signaling link to tell it to go for a  re-try.

    Note that in the UK the 11kV does not distribute neutral, so we have current transformers looking for imbalance, that perform the equivalent of a coarse RCD on the 11kV outbound, so a tree against a line is easily detected. This is 'SEF' - sensitive earth fault tripping. You'd expect SEF trip and re-try to be more common than line to line or line down faults , which would be likely to be flash and a permanent off.


    This doc from ENW  explains a typical UK policy -  you may find section 7,4 a good read.

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