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NETWORK / 22 / MAY 2018 O fgem figures show that the number of electricity interruptions was above 40 per 100 customers at 11 of the 14 network operators in 2016/17. Depending on the operator, customer interruptions lasted on average between just under 20 minutes and almost an hour. The regulator's Interruption Incentive Scheme sets targets for the volume and duration of power cuts and rewards or penalises network operators for exceeding or falling short of these targets. As well as this, direct pay - ments are required to customers for their inconvenience where network operators' performance falls short of standards set out for supply reliability. More than £1.8 million was paid out through this scheme in 2016/17. And this is all aside from the direct cost of sending out engineers to deal with faults. In short, there is plenty of incen - tive for the operators to focus on keeping the lights on. Unfortu- nately it just isn't an easy task. Steve White, head of net- work operations and control at UK Power Networks, says the company invests more than £500m in its electricity net - works every year. "Despite our best efforts to maintain and upgrade the elec- tricity network, some faults can still happen," he says. "Overhead power lines can be touched by tree branches, or be damaged by third parties including traffic accidents and farmers using high machinery. Underground power cables can also be damaged by third parties accidentally digging through them." UK Power Networks begins its efforts to prevent problems by producing local cable plans and e-maps to help workers and customers avoid its cables when digging. It also runs a public information campaign, titled Be Bright Stay Safe, which aims to remind people of the dangers of working too close to power lines. FAULT DETECTION TECHNOLOGIES Finding faults Helicopters, thermal imaging cameras, artificial intelligence and the internet of things are among the latest weapons as the battle against power cuts rages into the modern era. Greg Pitcher finds out more. The firm also listens out to customers, who o˜en give the first signal of an electricity interruption when they call to register it. "When people report a power cut, our engineers work by remote control from our control room, or by visiting site, to iden - tify the cause and start repairs or re-route the power supply." UK Power Networks took on 60 apprentices last year and runs its own training centres. It also invests in technology. "We use high-tech planes us - ing radar systems, and helicop- ters, to patrol overhead power line routes and identify where trees and vegetation is grow- ing too close to the lines," says White. "A key contributor to the reli- ability of our power networks is the Automatic Power Restora- tion System," he adds. "This in- novation identifies and isolates the location of a fault and re- routes power on the network so that only a few customers are affected for more than a couple of minutes." The operator has also invested in 65 thermal imaging cameras and uses 'cablesniffer' devices to hunt out fault loca - tions. Its Fusesaver device helps isolate a fault on to a single spur of a complex rural network. "Future proactive fault man - agement is also heavily depend- ent on network visibility down to the low voltage network, so we have just approved a £30m project to invest in low voltage visibility to help mitigate load- related faults in future." The low-voltage network Finding exactly where a fault has occurred is a major chal- lenge for the network operators. Jonathan Rodgers, future networks manager at technology supplier Kelvatek, explains the problem. "In terms of staff running about doing stuff, a large percentage of the work is on the low-voltage system," he says. "A high voltage fault gets attention because of the impact but there is 10 times more cable in the low-voltage network and it is not on poles, it's hidden under - ground, so it can't be inspected in the same way." Rodgers says poorly formed resin or natural ground move - ment can cause power cuts even without the impact of a third party. "Typically you will get water ingress into a damaged cable," he says. "Eventually you will get internal damage to the point where the 350amp-400amp fuse at the low voltage substation A UK Power Networks engineer using the Automatic Power Restoration System.