The UV intensity sensor reports the UV-C actually reaching the water. That is the measured variable a disinfection duty is controlled and alarmed on — not lamp hours and not lamp current — so a sensor that has drifted or fouled will under-report a healthy plant or, more seriously, over-report a failing one. This is the ÖNORM certified sensor variant, designated 2 V=200W. ÖNORM is the Austrian standards scheme; its drinking-water UV certification applies to the measuring chain as a whole, not to the sensor in isolation, so on a certified plant the specified sensor is part of what is certified and a general-purpose substitute is not equivalent. The designation is carried exactly as the manufacturer states it. Wedeco was founded in Herford, Germany in 1976 and is now a Xylem brand.