Siemens SITRANS LR 300, Instruction Manual, Page: 47 / 140

7ML19985CL02 SITRANS LR 300 – INSTRUCTION MANUAL Page 45
mm
mmm
Oper
ation
Operation
Overview
The SITRANS LR 300 is an advanced level-measuring device for liquids and slurries.
Using advanced pulse radar technology, the device calculates material level by emitting a
series of radar pulses and then analyzing their reflections.
The device consists of an enclosed electronic component mounted to a flanged antenna
component. The electronic component generates a 5.8 GHz (U.S.A. 6.3 GHz) radar signal
that is directed to the antenna, waveguide, or horn.
The radar signal is emitted axially from the antenna and propagates along this axis in a
defined conical beam decreasing in strength at a rate proportional to the square of the
change in distance.
The radar pulse detects the interface between the dielectric constant of the atmosphere
and that of the material being measured. Electro-magnetic wave propagation is not
sensitive to temperature and atmospheric conditions, or to variations in the medium.
Pulses are transmitted from the antenna at a fixed repetition rate. The reflected echoes
are received and digitally converted to an echo profile. The profile is analyzed to
determine the distance from the material surface to the flange face. This distance is used
as a basis for the display of material level and mA output.
Transceiver
The SITRANS LR 300 transceiver operates under one of five sets of pre-set conditions
(P003).
When the echoes are received, the relevant echo algorithm (P820) is applied to determine
the true material echo.
The measurement response limits the maximum rate at which the display and analog
output respond to changes in measurement. Determine the actual vessel filling and
emptying rates, and set P003 to a measurement response just faster than the maximum
filling or emptying rate (whichever is greater).
Measurement
Response
parameter P003
Max. fill/empty rate
P700/P701
Echo
verification
P711
Fail-Safe timer
P070
1 0.1 m/min slow 2 100
2 1 m/min 2 10
3 10 m/min 2 1
4 100 m/min 0 0.1
5 1000 m/min fast 0 0
SITRANS LR 300.book Page 45 Monday, June 10, 2002 7:18 PM