Siemens SITRANS L Operating Instructions Manual page 262

Glossary
confidence
see Echo Confidence.
damping
term applied to the performance of a device to denote the manner in which the
measurement settles to its steady indication after a change in the value of the level.
dB (decibel)
a unit used to measure the amplitude of signals.
derating
to decrease a rating suitable for normal conditions according to guidelines specified for
different conditions.
dielectric
a nonconductor of direct electric current. Many conductive liquids/electrolytes exhibit
dielectric properties; the relative dielectric constant of water is 80.
dielectric constant (dK)
the ability of a dielectric to store electrical potential energy under the influence of an electric
field. Also known as Relative Permittivity. An increase in the
dielectric constant is directly proportional to an increase in signal amplitude. The value is
usually given relative to a vacuum /dry air: the dielectric constant of air is 1. Many conductive
liquids/electrolytes exhibit dielectric properties; the relative dielectric constant of water is 80.
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
describes the quality of an echo. Higher values represent higher quality. Echo Threshold
defines the minimum value required for an echo to be accepted as valid and evaluated.
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.
262
SITRANS LR250 with FOUNDATION FIELDBUS
Operating Instructions, 09/2021, A5E32221411-AH