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Foresight Myth Busters For Low Voltage (LV) Networks

  • 02 September 2021

  • EA Technology

Myth 1: Nothing ever happens on LV networks
Not True

Since the LV monitoring equipment being deployed on the Foresight, over 35,000 events have been recorded relating to pre-fault activity and quality of supply issues. This newfound visibility of the network has given Northern Powergrid the opportunity to proactively find and fix impending faults and gain insights into the quality of supply issues which include flicker, off supplies and illegal extraction to name but a few.

Myth 2: Most LV cable faults are single phase
Not True

Faults that cause off supplies due to protection operation are mostly multiphase. Pre-fault events are however mostly single phase.

Myth 3: Replacing just the fuse that is blown should be good enough for transient faults.
Not True

Most faults are multiphase, but it is easy to report them as single phase as only one fuse blows. The fuses on the respective phases on a multiphase fault are essentially in a race. One fuse will always interrupt the current first, the other fuse(s) is(are) pretty much exhausted, and unlike Mo Farrah, do not fully recover before being asked to step up and run a marathon again. The next time the fault occurs the weakest fuse goes leaving the new one now tired and so it flip-flops until the fault goes permanent.

Myth 4: Phase to phase faults do not generate any significant neutral current.
Not True

Most of them do. The ALVIN Guard utilises this current to localise the source of the fault to a particular feeder.

Myth 5: You cannot find faults until they go permanent which usually means customers are off supply.
Not True

Actually, you can. This is what the foresight project has proven. Not only can you find them, but you can fix them too. "Find and Fix before fault" is becoming a practical reality