Instrumentation Monthly Test | Measurement | Control
Non contact radar level sensors increase reliability on river sluices for Canal & River Trust
On the River Weaver, the Dutton sluice site consists of eight large sluice gates lifted by ‘Rotork’ actuators. The sluices operate depending on the water level, this is a key measurement point and the level monitoring needs to be very accurate. – the navigation is closed to river traffic if the water level is too high. At this site, the level of the River Weaver is now measured by four instruments: two ultrasonic sensors (for redundancy) are mounted in stilling tubes. These tubes are required to reduce ‘loss of echo’ issues from weather and surface conditions. However the tubes can require substantial engineering to install, and generally they need ongoing on site maintenance to prevent blockages, or repairs to keep measurement errors to a minimum. Even with this stilling tube installation, the SCADA Maintenance engineer commented, “In recent years we have experienced issues where either one or both of the ultrasonic sensors loses echo or “drifts” causing level sensor failure alarms to be sent out.”
As a result Canal & River Trust have installed two other devices alongside, VEGAPULS WL61 water radars, as test instruments. As they are unaffected by weather or surface conditions, these were simply mounted on a “unistrut” adjacent to the stilling tubes and CRT have compared the data from both sets of instruments over several months. There has been no “drift” with the WL61 water radars since installation. “Whilst we have seen occasions where the water level on one or both of the ultrasonic units rises, the radars have not.” Continues the engineer. “As far as I can see, the WL61 radars provide more reliable data than the ultrasonic devices. My concern with the ultrasonic sensors is that “drift” could create nuisance alarms and result in staff call outs.” There are also the ongoing maintenance requirements associated with the stilling tubes. “I do not have these concerns with the WL61s. In addition, I have confidence in the support from VEGA should an issue arise with any of the instruments at a later date.”
As the engineer summed up, “I am pleased with the quality and performance of the VEGAPULS WL61 level radars we will be installing these in place of the ultrasonic sensors at the other River Weaver sites and in other CRT sites as we replace older equipment.”
This yet another example of how on open water applications, radar is increasing reliability, accuracy and lowering TOTEX costs. For more information and other case studies, please contact VEGA: info.uk@vega.com or call sales on 01444870055