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 1V=200W. ÖNORM is the Austrian standards scheme; its drinking-water UV certification applies to the measuring chain as a whole, so on a certified plant the specified sensor is part of what is certified. The designation is carried exactly as the manufacturer states it. Wedeco was founded in Herford, Germany in 1976 and is now a Xylem brand.