Mode Of Operation; Principle Of Measurement - Siemens SITRANS DA400 Operating Instructions Manual

Description

3.4 Mode of operation

3.4 Mode of operation
3.4.1

Principle of measurement

Mode of operation
The SITRANS DA400 uses acoustic emission sensors to detect high-frequency acoustic
vibrations. These vibrations are caused by:
● friction and impact of solids in:
● 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 and
attenuated in the air. Therefore, the sensor does not sense background noise and allows for
non-invasive process and equipment monitoring.
The SITRANS DA400 provides a measuring value in the form of sound level L, which is
dependent on the acoustic power. The sound level L produced by the material flow is
dependent on the mechanical power. L is calculated with the following formula:
L = 10 log (η*P
L
η
P
mech
P
0
If a preset limit is exceeded, SITRANS DA400 issues a pre- or main alarm. Depending on
the configuration, the alarm signals are output on the digital output. Additionally or
alternatively, a PROFIBUS interface is available, which allows for connecting to control
systems.
14
– pipes
– chutes
– conveyors
/P )
mech 0
Sound level
Energy transfer coefficient, from mechanical to acoustic
Mechanical output
Reference output
SITRANS DA400 for material flow monitoring with protection against explosion
Operating Instructions, 09/2007, A5E00841152-01