Siemens sitrans PROBE LU - Specific Instructions for Hazardous Areas

Page 106 SITRANS Probe LU (HART) – OPERATING INSTRUCTIONS A5E32337695
Glossary
derating: to decrease a rating suitable for normal conditions according to guidelines specified
for different conditions.
dielectric: a nonconductor of direct electric current.
echo: a signal that has been reflected with sufficient magnitude and delay to be perceived in
some manner as a signal distinct from that directly transmitted. Echoes are frequently
measured in decibels relative to the directly transmitted signal.
echo confidence: the recognition of the validity of the echo. A measure of echo reliability.
Echo Lock Window: a window centered on an echo in order to locate and display the echo’s
position and true reading. Echoes outside the window are not immediately processed.
Echo Marker: a marker that points to the processed echo.
Echo Processing: the process by which the device determines echoes.
Echo Strength: describes the strength of the selected echo in dB above 1 μV rms.
Echo Profile: a graphical display of a processed echo.
electrical noise: unwanted electrical signals that produce undesirable effects in the circuits of
the control systems in which they occur.
false echo: any echo which is not the echo from the desired target. Generally, false echoes are
created by vessel obstructions.
frequency: the number of periods occurring per unit time. Frequency may be stated in cycles
per second.
hertz (Hz): unit of frequency, one cycle per second. 1 kilohertz (kHz) is equal to 10
3
Hz.
HART: Highway Addressable Remote Transducer. An open communication protocol used to
address field instruments.
inductance: the property of an electric circuit by virtue of which a varying current induces an
electromotive force in that circuit or in a neighboring circuit. The unit is a Henry.
multiple echoes: secondary echoes that appear as double, triple, or quadruple echoes in the
distance from the target echo.
Near Blanking: see Blanking
nozzle: a length of pipe mounted onto a vessel that supports the flange.
parameters: in programming, variables that are given constant values for specific purposes or
processes.