Distribution network operators in UK and Ireland have installed thousands of Ensto’s Auguste load-break switches. Let’s ask SP Energy Networks, why they have trusted the product line and its manufacturer for twenty years.
SP Energy Networks operates the electricity distribution networks in Central & Southern Scotland, North Wales, Merseyside, Cheshire & North Shropshire, supplying 3.5 million connected customers. The distribution networks include over 40,000 km of overhead lines (OHL), which have almost three thousand telecontrollable or automated points installed.
The company has twenty years’ experience of Ensto Auguste load-break switches, still sometimes called by their former brand name, Soule. Jamie McDonald, Lead Engineer, OHL Standards, at SP Energy Networks counts that there are around 1700 units installed across the network.
– We use Auguste switches for two main purposes on our 11kV network. Firstly, they are installed on radial spur lines as auto sectionalising disconnectors. When there is a fault on the spur, they disconnect the spur line, reducing the effect of the fault on customer supplies on the healthy main line, he says.
– Secondly, they are installed in place of 11kV main line air break switch disconnectors (ABSD) at critical network switching points. We use these as telecontrollable or automated switching points, allowing quicker identification of faulty sections and restoration of customer supplies.
Senior Standards Engineer at SP Energy Networks, Ewan Gilliland, says that Augustes have been especially useful for both those purposes mentioned.
– When disconnecting faulty sections of OHLs, they have some great benefits over traditional auto sectionalizing links (ASL). Because they operate all three phases at once, the risk of one phase not operating correctly is eliminated and reduces the risk of damage due to ferro-resonance.
– In addition to that, they have a programmable setting for the fault current that we want them to operate at. ASLs have only one setting to cover both overcurrent and earth fault, and we have some low current faults where ASLs do not operate. Auguste switches can instead have a low earth fault setting (9A) but still keep a high overcurrent setting (100A) to allow excellent discrimination between fault types and high load.
Ewan gives some examples of Augustes performance and how the company has benefited from using them over other alternatives. There are very remote network switch points that are difficult for operator access. According to him, after installing Augustes with telecontrol, the customer minutes lost have been reduced significantly.
– On longer and remote spur lines we have had repetitive transient faults that have a low fault current. The existing ASLs fail to operate there and we have installed Augustes. Due to the option to select a low earth fault setting, they detect the fault and operate successfully to allow the disconnection of the faulty section of network, he describes.
Distribution network operators (DNOs) in UK and Ireland have installed thousands of Augustes in their networks during the last decades. The benefits they bring as part of network automation in connection to supervisory control and data acquisition system (SCADA) are well known.
They are easy to install, reliable and have very low maintenance requirement components. They are the key building blocks of OHL network automation of today and in future. However, most importantly, for DNOs, they improve the indexes of interruption duration (SAIDI) and frequency (SAIFI) with minimal investment costs.
John Carolan, Sales Manager of UK & Ireland at Ensto Utility Networks, says the reduction in both customer minutes lost (CML) and customer Interruptions (CI) is the major criteria to invest in Augustes. In case of SP Energy Networks, for example, the company’s own estimate of avoided CI/CML penalties exceeds £7 million per year.
He sees Ensto’s role as a trusted partner to reduce the customers’ costs in every aspect by continually supporting their needs with evolution of the solutions. That means strong presence, regular meetings and capacity to develop and present new product features desired, as has been done with SP Energy Networks.
– Auguste represents advanced network automation, but still is a cost-effective solution with a very short pay-back, he says. The investment decision made even easier by a list of approvals including ENA Notice of Conformity Certificate and all relevant IEC standards.
– Installation and commissioning is simple to complete on site. And once on the pole, Auguste keeps working maintenance free and provides customers with a long-life asset that provides continued benefits for upwards of twenty years, John Carolan concludes.