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Topic Title: Power Cuts.
Topic Summary: Short Duration.
Created On: 22 September 2017 08:13 AM
Status: Read Only
Linear : Threading : Single : Branch
 Power Cuts.   - Zoomup - 22 September 2017 08:13 AM  
 Power Cuts.   - broadgage - 22 September 2017 09:01 AM  
 Power Cuts.   - kellyselectric - 22 September 2017 12:19 PM  
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 22 September 2017 08:13 AM
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Posts: 3657
Joined: 20 February 2014

Mornin All,
we are suffering from many and regular power cuts, or power outages as some call them, here in Norfolk. The events are regular and short lived and affect many areas. The cuts may be for a few minutes or up to about twenty minutes in some cases. What is going on? Are others suffering in the same way? The cuts occur in good as well as bad weather, day and night.


 22 September 2017 09:01 AM
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Joined: 07 August 2007

Possibly a change of policy or safety rules by the DNO.
Consider for example two transformers, or lines connected to transformers that were formerly worked in parallel. The resultant available fault current might be excessive for circuit breakers or other equipment.
So instead of lines A and B jointly feeding villages X and Y, you now have line A supplies village X and line B supplies village Y.
Any fault then blacks out one village until manual switching restores both supplies via the sound route.

Similar arguments apply at LV, excessive fault currents may have led to less interconnection and less redundancy. For example feeding LV mains from only one end instead of from both ends.
 22 September 2017 12:19 PM
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Joined: 22 July 2016

Do they feed LVmains from both ends together? I thought that was just a London thing. I think it might be a tree or something momentarily shorting an HV line maybe the long delay is if someones got to change an HV fuse and the shorter time Is if the autoreclosers just have to do their thing

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