Appendix A: Technical Reference; Principles Of Operation; Measurement Response - Siemens SITRANS LR200 Instruction Manual

Appendix A: Technical Reference

Principles of Operation

SITRANS LR 200 is a sophisticated radar instrument that uses advanced microwave
pulse technology
slurries. Radar level measurement uses the time of flight principle to determine distance
to a material surface. The transmit time is directly proportional (to the distance to the
material).
Pulse radar uses polarized electromagnetic waves. Microwave pulses are emitted from
the antenna at a fixed repetition rate, and reflect off the interface between two materials
with different dielectric constants (the atmosphere and the material being monitored).
The echo is detected by a receiver, and the transmit time is used to calculate level.
Electromagnetic wave propagation is virtually unaffected by temperature or pressure
changes, or by changes in the vapor or dust levels inside a vessel.
SITRANS LR 200 consists of an enclosed electronic component coupled to an antenna
and process connection. The electronic component generates a radar signal at 5.8 GHz
(6.3 GHz in North America) that is directed to the antenna.
The signal is emitted from the antenna, and the reflected echoes are digitally converted
to an echo profile. The profile is analyzed to determine the distance from the material
surface to the reference point on the instrument. This distance is used as a basis for the
display of material level and output.

Measurement Response

The measurement response (response rate) limits the maximum rate at which the
display and output respond to changes in the measurement. Once the real process fill/
empty rate (m/s) is established, a response rate can be selected that is slightly higher
than the application rate. The response rate automatically adjusts the filters that affect
the output response rate.
There are three preset options: slow, medium, and fast.
Related
Parameters
Values
If none of the preset options is satisfactory, the filters can be adjusted individually.
1.
The microwave output level is significantly less than that emitted from cellular phones.
7ML19985HP01 SITRANS LR 200 (PROFIBUS PA) – INSTRUCTION MANUAL
1
to provide non-contacting continuous level measurement in liquids or
Response LOE Timer
Rate (minutes)
1 * slow 100
2 medium 10
3 fast 1
Empty
Fill Rate
Rate
0.1 m/minute 0.1 m/minute
1 m/minute 1 m/minute
10 m/minute 10 m/minute
Echo
Lock
material
2
agitator
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