The Great Dunchideock Blackout Saga

We recently suffered a power outage, or power cut as we prefer to call such things here in the UK. This wasn’t any old power outage either. Let me explain.

The lights went out at 17:44 on Friday April 11th 2014. I hurriedly powered down everything in the lab and office except my laptop and our broadband router, which was by then being powered from the battery in an uninterruptible power supply. When the lights hadn’t come back on a few minutes later I telephoned our local Distribution Network Operator (DNO for short), Western Power Distribution, to enquire what the problem was, and when it might be fixed. WPD’s automated system suggested that our power should be restored by about 21:00 that evening.

9 o’clock came and went, by which time the batteries in my laptop and UPS were flat. I called WPD again, to be informed that the latest estimate for the time at which I would be able to get connected to the internet once again would be 01:00 on Saturday morning. I figured I’d allow WPD a bit of leeway, and eventually went to bed having set the alarm on my smartphone for 02:00. The alarm went off, but the lights still hadn’t come back on.  I phoned Western Power again to be informed that things should be back to normal in an hour or so. Bleary eyed I returned to bed.

When I arose next morning I wasn’t in need of any lights, but my router and laptop were working once again. There was, however, the continuous drone of an engine audible not too far away so I set out to investigate by following the sound, and here is what I discovered:

Generator on the track to Haldon Belvedere on April 12th 2014

Diesel generator on the track to Haldon Belvedere on April 12th 2014

Another call to Western Power Distribution elicited some further information. I managed to speak to WPD’s standby manager for the day, who explained what had happened the previous evening. Initally over 300 properties had been without electricity following the operation of an automatic circuit recloser mounted on pole NLT1M in Alphington, as shown at the top right of the map of WPD’s network below (click the image for a larger version), and in this photo I took subsequently:

Schneider pole mounted recloser and air break isolator in Alphington

Schneider U-Series pole mounted recloser and an air break isolator in Alphington

WPD map of 11 kV and 33 kV cables Southwest of Exeter

WPD map of 11 kV (red) and 33 kV (green) cables south west of Exeter

At that point everything powered via the 11 kV 3 phase (thick red) cables running from top right to bottom left of WPD’s map was without electricity. By around 21:00 the problem had been isolated to somewhere in the bottom left corner of the map, and power now reached as far as pole NLK19, near the north east corner of The Lord Haldon Hotel car park.

Pole 31NLK19, whilst The Lord Haldon Hotel and The Haldon Belvedere were running from WPD generators

Pole 31NLK19, draped with extra cables, whilst The Lord Haldon Hotel and The Haldon Belvedere were running from WPD generators

Unfortunately the hotel itself, which had a wedding reception booked that night, and everyone else in our corner of the village of Dunchideock and Haldon Hill were still without power, and WPD still didn’t know where the fault was. I am assured by a local resident that once it had got dark his wife noticed some arcing at the top of an electricity pole in a field behind his house, so he drove to the hotel car park and informed the WPD engineers gathered there about her discovery. The problem ultimately proved to be a faulty pole top cable termination, shown below in situ together with some inquisitive lambs:

A 48 year old cable termination at the top of pole NLK20

Youthful interest is shown in a big hole in the ground

Some youthful interest is shown in a big hole in the ground

By the time the likelihood that this was indeed the ultimate cause of the problem had been established time was pressing. According to WPD they have a self imposed 12 hour time limit on turning the power back on after any interruption in supply, and there was no way this problem would be fixed within that timeframe. That being the case some generators would be required, which presented WPD with another big headache. It seems there had been some other problems in Devon on the same day, and there weren’t enough generators in Exeter to go around, so WPD brought some more in from Torbay. That still wasn’t adequate for the scale of the problem, so they brought some more in from Taunton. Even that wasn’t sufficient, so finally they had to hire a few more from Bristol, one of which was emitting the dulcet tones that greeted me on Saturday morning. Here’s one of WPD’s own generators, that was located a bit further up the road near the entrance to the hotel:

WPD Generator hard at work outside Pen Hill Cottage

WPD diesel generator hard at work outside Pen Hill Cottage

All in all, by the time everyone affected had their electricity supply restored, which in our case seems to have been at around 3:30 on Saturday morning, 9 diesel generators were scattered across the north side and ridge of Haldon Hill. WPD assured me there was no danger of any further power cuts, since every 12 hours or so they would be hauling a bowser around the local vicinity to top up the tanks of any generator that might be running low on diesel fuel.

Whilst they didn’t have such a thing last time I checked, during the recent winter storms, I was also informed that Western Power now provide an online power cut map. This is how it looked on the morning of Saturday April 12th 2014:

Western Power Distribution power cut map at 08:39 BST on Saturday April 12th

Western Power Distribution power cut map at 08:39 BST on Saturday April 12th


It seems as though “running off a generator” doesn’t count as a “power cut”, because Dunchideock isn’t on that map, all of which meant that WPD could now fix the problem as and when time permitted. Here’s how things were looking by Sunday evening:

By Monday morning the epoxy resin in the Lovink red box had set, the big hole in the ground was filled in, and we were all back on mains power once again. All of which raises a few questions, in my mind at least.

In my conversations with WPD’s duty engineers I enquired whether this particular failure might be in any way attributable to the recent wet and windy winter weather here in South West England I alluded to earlier. I was told that while a causal link with any single failure was impossible to establish, it was conceivable that WPD’s electricity distribution network had suffered additional “stress” due to increased lightning strikes and the potential for trees to be more easily toppled by strong winds whilst their roots were sitting in sodden soil. I also idly enquired about the stresses placed on the network by renewable generation in the South West, but that story will require an article of its own at the very least.

In the meantime I’ve been pondering how this saga would have panned out if some of the homes in Dunchideock had already been in possession of an electric vehicle and some vehicle to home or even vehicle to grid technology. Since the powers that be here in the UK don’t seem to be wild about either of those concepts maybe a pile of shiny new lithium ion batteries from Tesla in the corner of each garage in Dunchideock might be more realistic to speculate about, or at the very least some second user EV batteries that are at least receiving some R&D funding on this side of the Atlantic? In that case perhaps we should add distributed storage to grid (or S2G for short) to our list of TLAs under consideration?

The lights wouldn’t have gone out in any V2H or storage equipped home. Their broadband would have kept on working too, so information about the failure could have been swiftly despatched to WPD’s control centre to enable the location of the fault to be pinpointed more swiftly. If some people had V2G and/or S2G installed as well, and subject to being suitably reimbursed for their public spiritedness, they could have kept their neighbours’ lights on as well as their own provided that WPD’s equipment was capable of sectionalising their network with greater granularity than at present. As luck would have it there is a pile of such equipment already in Dunchideock, although it’s only in the V2G lab at the moment rather than attached to any of the WPD poles I’ve mentioned apart from the one in Alphington, or in the corner of anyone else’s garage in Dunchideock. Here’s what a remote terminal unit looks like from the outside:

A Lucy Switchgear Gemini Remote Terminal Unit plus PakNet PAD

A Lucy Switchgear Gemini Remote Terminal Unit plus PakNet PAD

and here’s what the ARM powered CPU board on the inside looks like:

Gemini ARM CPU card

A Lucy Switchgear Gemini ARM CPU card, connected to the internet

As you can see, in actual fact it’s not a whole lot different to a Raspberry Pi, or the guts of the average smartphone for that matter:

A Raspberry Pi model B, connected to the internet

A Raspberry Pi model B, connected to the internet

Hence such a piece of electronics wouldn’t in and of itself add a whole lot to the price of an electric vehicle and/or a garage in Dunchideock, or anywhere else on the planet for that matter.

In conclusion, I also cannot help but wonder how much the Great Dunchideock Blackout cost Western Power Distribution, how much the evidently changing climate in this part of the world is costing and will cost them, and how their electricity distribution network is coping with the assorted stresses and strains generated by all the renewable power sources currently being tacked onto it down here in not so Sunny South West England that do not currently have any form of energy storage associated with them.

4 thoughts on “The Great Dunchideock Blackout Saga

  1. As if in confirmation of my theory outlined above, I have just been speaking via telephone to the Sustainability Manager of South Gloucestershire Council about the potential benefits of distributed energy storage. She told me she could no longer see the web page I was describing because the council offices had just suffered a power cut.

    This is what WPD’s power cut map currently has to say on the matter:

    WPD power cut map for South Gloucestershire at 15:15 BST on May 15th 2014

  2. It seems that Chipping Sodbury is part of Western Power Distribution’s “West Midlands” area. Having finally worked out who to ask about South Gloucestershire Council’s recent power cut, I am reliably informed that:

    The fault occurred at 15:00:49 hrs which caused the Cowmills/Safeways 11kV Circuit Breaker on Section X of our 11kV switchboard at Chipping Sodbury sub-station to trip. This trip initialised a sequence scheme to operate allowing automated switching to occur. This sequence began isolating sections and restoring supplies to parts of the network as follows

    Restoration 1 129 customers restored at 15:14:25hrs

    Restoration 2 535 customers restored at 15:20:20hrs

    Restoration 3 136 customers restored at 15:27:16hrs

    Restoration 4 110 customers restored at 15:34:00hrs

    During this period we had also mobilised manual switching staff who had been able to locate the fault visually at one of our switch positions which allowed us to isolate the faulty section completely and restore all supplies at 15:38:19 hrs.

    The fault was at a cable termination box at Brookfield Close substation 62025 on the circuit towards Tudor Hall substation 7986. This was then dug out and repaired overnight with the network returned to normal running arrangements on 16/5/14.

    Given the time taken to restore supply to South Gloucestershire Council and everyone else in the area on this occasion, long before the fault itself was fixed, it does rather make one wish that Dunchideock’s electricity supply was part of a “ring”, rather than merely a “spoke” emanating from a “hub” in Exeter!

  3. Looking for something else and have just found and read your article. You have probably been lectured at length on the operation of rural distribution networks but just in case here is a snapshot. It is both difficult and costly to connect everyone onto a ring circuit, indeed it is far from cost efficient, if you live in a rural area then one of the penalties for this is reduced services, no mains gas (probably) low speed broadband (probably), limited main drainage, bus services, shops, etc. A single phase spur is even more difficult to connect as a ring, due to network imbalance. I no longer work for the Electricity Distribution business, having retired in 2002 but I am constantly amazed by the advances made in reconnecting customers either by remote switching devices, be it automatic or deliberate manual intervention. The costs of this are borne by the wider users of the network in the same way that solar panel and wind generation subsidies are paid for by all of us. Unregulated and I am not a fan of the regulator, rural networks would not be served as well as they are now because the economics do not stack up.

    By the way luck as always plays a big part, where the fault is, the time of day it occurs, has there been a storm, rural networks are mostly overhead lines and prone to storm damage, and how difficult it is to access the fault location. There are also issues with the System Network and Operational Safety which make connecting the output from residential power supply to the DNO system infeasible. Batteries and an inverter or a standard suitcase generator, properly wired in accordance with the wring regulations, are fine and will also provide you with a limited amount of power in the event that there is insufficient generation to meet demand and rota load shedding is put into operation to secure the stability of the Grid.

  4. Thanks for popping in Ian,

    I’ve been working on automating electricity distribution networks since the late 90s, so I’m familiar with the “conventional wisdom” in the industry that you seem (to me at least) to be outlining. Here on the edge of Dunchideock we have no mains gas, no mains water and low speed broadband, though salespeople do keep phoning us up to point out that “fibre” is now available (as long as we sign a long term contract). There isn’t even a pub in the village. From time to time we also have to survive without mains electricity!

    There certainly seems to have been a fair bit of storm damage recently, across WPD’s patch in general and the Haldon Hills in particular. If you’re familiar with the acronym enshrined in our company name you’ll know that using the batteries in plug in electric vehicles to power homes and businesses are of particular interest, as are “static” storage devices.

    Whilst there are certainly safety issues associated with powering “the DNO system” during a “power cut” are they in fact insurmountable? There are certainly a number of residences in Dunchideock equipped with Solar PV panels and grid-tie inverters. There are even local businesses with them too:

    That being the case, your “infeasible” would seem to be less than entirely accurate?

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