Siemens SITRANS DA400 Operating Instructions Manual

Also see for SITRANS DA400: Operating instructions Operating instructions Operating instructions

Description3.4 Mode of operationSITRANS DA400 for material flow monitoring with protection against explosion14 Operating Instructions, 09/2007, A5E00841152-013.4 Mode of operation3.4.1 Principle of measurementMode of operationThe SITRANS DA400 uses acoustic emission sensors to detect high-frequency acousticvibrations. These vibrations are caused by:● friction and impact of solids in:– pipes– chutes– conveyors● friction and contact between mechanical parts● bubbles bursting● cavitation● turbulence formation in gas and liquid flows.Acoustic vibrations conduct well in solids such as metals but are greatly diffused andattenuated in the air. Therefore, the sensor does not sense background noise and allows fornon-invasive process and equipment monitoring.The SITRANS DA400 provides a measuring value in the form of sound level L, which isdependent on the acoustic power. The sound level L produced by the material flow isdependent on the mechanical power. L is calculated with the following formula:L = 10 log (η*P mech/P 0)L Sound levelη Energy transfer coefficient, from mechanical to acousticP mech Mechanical outputP 0 Reference outputIf a preset limit is exceeded, SITRANS DA400 issues a pre- or main alarm. Depending onthe configuration, the alarm signals are output on the digital output. Additionally oralternatively, a PROFIBUS interface is available, which allows for connecting to controlsystems.