Water and Effluent Treatment Magazine
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16 WET NEWS JANUARY 2015 Existing switchgear and electrical distribution equipment have been retrofitted so that each of the substations are now supported by two Ring Main Units and one control box Power to the Bough Beech WTW • Sutton and East Surrey Water had to protect Bough Beech WTW from power outages. However, mobile coverage in the area proved a problem. TECHKNOW 1 The solution involved upgrading the physical switchgear equipment plus a bespoke switchover programme 2 A new 11kv Ring Main Unit as well as new switchgear, all designed were installed 3 Existing switchgear and electrical distribution equipment were retrofitted 4 The new sequence was designed to run through three substations and six switches S utton and East Surrey Wa- ter is a water-only compa- ny serving customers in East Surrey, parts of West Sus- sex, west Kent and South Lon- don. Its supply area covers 835km2, much of it rural and supplies drinking water to ap- proximately 670,000 consumers in 282,000 properties. To improve resilience and customer service, the company has been undertaking a signifi- cant modernisation project to ensure the Bough Beech Water Treatment Works (WTW) was equipped to meet the future needs of the region. As a result it asked Lucy Electric, a global THE VERDICT • "...Sequencing solutions have ensured that we can stay operational with a minimum impact in the case of an external fault. This gives us piece of mind and will also save costs" Sutton and East Surrey Water ONSITE Asset management leader in switching, protection and automation solutions for medium and low voltage electri- cal distribution systems, to develop a bespoke solution to protect the treatment plant in case of a power outage and to improve stability and limit disruption. Sutton and East Surrey Water wanted to protect the plant from any potential disruption caused by loss of power from the regional supplier or during rou- tine maintenance. Due to the remote location, there was only one connection into the treat- ment plant. That meant that if power was lost on site for any reason, the plant would have to rely on the local generator to create electricity. Power outage The site already had its own generators in place, and when the supply from the local elec- tricity supplier is lost then the site automatically switches over. However, bringing the seven onsite transformers online at the same time would create a current / power inrush problem for the generators and cause them to trip out. This meant that in the case of a power outage, a specialist electrician would have to be brought in to recalibrate the switches. This was both expen- sive, and would create a period of downtime for the treatment plant, which has obvious nega- The equipment was able to cope with the bespoke sequencing programme developed to allow for the transformers to undergo a staged re-energisation of the ring in case of a power outage Once the automation sequence is started, all switches should have operated after 225 seconds PROJECT SPECS • Develop a bespoke solution to protect Bough Beech WTW in case of a power outage • Improve stability and limit disruption • Bring the seven onsite transformers online at the same time without them tripping out