User manual VAISALA LM21 DATASHEET

[. . . ] Box 26, FIN-00421 Helsinki, FINLAND Tel: +358 9 894 91 Fax: +358 9 8949 2485 Email: industrialsales@vaisala. com www. vaisala. com Vaisala Background Luminance Sensor LM21 Features/Benefits · Intelligent, stand-alone sensor · Extensive self-diagnostics · Window contamination measurement and compensation · Optical path blockage detection · High power heaters to prevent snow accumulation · Calibration traceable to measurement standards · Field calibration device available Vaisala Background Luminance Sensor LM21 is an intelligent, standalone precision photometer. The Vaisala Background Luminance Sensor LM21 is a part of Vaisala's airport RVR assessment equipment. The background luminance has an effect on the distinctiveness of the runway lights as seen by a pilot. Comprehensive selfdiagnostics The LM21 is an intelligent, stand-alone sensor. [. . . ] The LM21 sends the measurement data to the interface unit of a Vaisala transmissometer or forward scatter visibility sensor. The interface unit combines both the visibility and background luminance data into the same message and sends it to the main RVR computer. The LM21 can be connected to the Vaisala Transmissometers LT31 and MITRAS, as well as to the Vaisala Forward Scatter Sensors FS11 and FD12. The LT31 and FS11 are connected using a RS-485 serial line. For the MITRAS and FD12 connection, the measurement result is converted to a frequency that corresponds linearly to cd/m2 divided by 10. automatically when the LMA21 is connected to the Vaisala Background Luminance Sensor LM21. The LM21 reads the calibration coefficients from the LMA21 memory and performs the calibration. The status and result of the calibration is displayed with 5 LED indicators on the cover of the LMA21. Easy to calibrate The calibration of the LM21 is traceable to the measurement standards. The Vaisala Field Calibrator LMA21 is a unique field calibration device that is available for quick field calibration. It provides a stabilized and diffused white light beam for the LM21 calibration. The calibration coefficients for light intensity have been defined during factory calibration, and stored in the LMA21 memory. [. . . ] This compliance has been verified according to the following EMC directives: Radiated emissions EN55022 Radiated susceptibility IEC 1000-4-3, 10 V/m Conducted emissions EN55022 Conducted susceptibility IEC 1000-4-6 EFT immunity IEC 1000-4-4 ESD immunity IEC 1000-4-2 Dimensions Dimensions in mm. Environmental Operating temperature Operating humidity -40 . . . 100 %RH 142 100 154 31 Specifications subject to change without prior notice. [. . . ]