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High Voltage line arcing.

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High Voltage line arcing.

Post by colly0410 » Sat Dec 26, 2015 7:00 pm

Been watching videos on you tube of HV lines arcing, some of them seem to be shorting out to earth. (through trees, cranes etc) Would a 3 phase HV line have some kind of earth leakage gubbins (RCD?) to cut the power if an earth fault developed? I can understand that a SWER line (electric washing line) would arc to earth as it would think it's in normal operation.

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Re: High Voltage line arcing.

Post by Katie Bush » Sat Dec 26, 2015 8:15 pm

All I can say is that our power supply has occasional unexpected drop-outs.. The power cuts out in the event of a short to ground, or inter-phase fault, then resets itself within a minute.. If the fault persists, there are three automated attempts to restore power, then if the third attempt fails, the drop-out becomes a lock-out, requiring human intervention to clear the fault and restore normal working.

I only discovered that by talking to the line maintenance crew a few years ago, during one of their 'hedge and tree' lopping exercises.


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Re: High Voltage line arcing.

Post by Ed Dinning » Wed Feb 17, 2016 9:30 pm

Hi Folks, just seen this one.
Most HV distribution in rural areas is on lines in the 3.3 to 33Kv range and the system is delta connected without a neutral (and earth).
These rural lines are normally monitored for voltage balance to earth but do not necessarily trip if one of the lines is earthed due to a branch falling on it. If the fault persists it can damage insulation, but it normally only sends and alarm, hence protecting rural supplies.

The HV transmission lines (66KV, 132KV, 275KV and 400KV) are star connected and are tripped very quickly in the event of a line to neutral; or earth fault.


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