A project to improve the SCADA (supervisory control and data acquisition) system at a water treatment works experienced a problem when on-site signals dropped out intermittently with no explanation. Any unexplained loss of communication on a site’s SCADA system has the potential to impact continuity of supply and water quality – so it was vital to resolve the issue quickly.
Contractor Software Links was tasked with upgrading the system and, believing that the issue lay with the lightning protection system, they called Furse in to investigate. Lightning protection is essential to protect utilities against the effects of lightning strikes and Software Links had taken the correct approach of creating physical earthing points at discrete positions around the system.
Furse identified that the issue was caused by different earthing conditions along the lengthy signal cable between nodes and the control room. The difference in conditions effectively blocked communications through current leakage, meaning that a signal would be sent at 6V, but the receiver at the other end of the cable might only read 1-2V.
To resolve the issue, Furse supplied a total of six units of its latest ESP (electronic systems protection) product within a month of its first call from Software Links.
Following installation of the new ESP devices, Software Links’ engineer reported that the devices had resolved the issue and there was no deterioration in the voltages or the signal on the SCADA system. This means that Bristol Water’s communications system now operates as expected, maintaining continuity of water supply.
“Furse introduced the specialist ESP devices in mid 2014, only a few months before Software Links reported its issues. This meant that we were able to give Bristol Water and Software Links a lightning fast response,” said Keith Herrington, Furse R&D Manager.
Furse developed the ESP for the type of SCADA system that is typical in the water industry. They are galvanically isolated from earth and only connect to earth when they detect an overvoltage from lightning or switching transients. This means that under normal operation they are not earthed at all. This protects the signals from the effects of different earthing conditions and protects critical process equipment against transient over voltages, which helps to enhance its operating life.
The ESP devices is available as a standard-sized product, as well as a slimline unit for applications, where space is at a premium and the Quad unit that houses multiple protection units in a single enclosure for high density applications.