User's Manual
Table Of Contents
- Table of Contents
- SITRANS LR250 Overview
- Specifications
- Installation
- Wiring
- Operating via the handheld programmer
- Operating via SIMATIC PDM
- Functions in SIMATIC PDM
- Quick Start Wizard via SIMATIC PDM
- Changing parameter settings using SIMATIC PDM
- Parameters accessed via pull-down menus
- Operating via AMS Device Manager
- Functions in AMS Device Manager
- Features of AMS Device Manager
- Device Description (DD)
- Configuring a new device
- Startup
- Pull-down menu access
- Device configuration
- Quick Start Wizard via AMS Device Manager
- Maintenance and Diagnostics
- Remaining Device Lifetime [see Remaining Device Lifetime (4.2.) on page 99]
- Remaining Sensor Lifetime [see Remaining Sensor Lifetime (4.3.) on page 102]
- Service Schedule [see Service Schedule (4.4.) on page 105]
- Calibration Schedule [see Calibration Schedule (4.5.) on page 108]
- Electronic Temperature
- Wear (see Wear on page 56)
- Communication
- Security
- Device Diagnostics
- AMS Menu Structure
- Functions in AMS Device Manager
- Parameter Reference
- 1. Quick Start
- 2. Setup
- 3. Diagnostics
- 4. Service
- 5. Communication
- 6. Security
- 7. Language
- Appendix A: Alphabetical Parameter List
- Appendix B: Troubleshooting
- Appendix C: Maintenance
- Appendix D: Technical Reference
- Principles of Operation
- Echo Processing
- Analog Output
- Maximum Process Temperature Chart
- Process Pressure/Temperature derating curves
- Loop power
- Appendix E: Application Examples
- Appendix F: HART Communications
- Appendix G: ATEX Certificates
- Appendix H: Firmware Revision History
- Glossary
- Index
- LCD menu structure
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D: Technical Reference
Appendix D: Technical Reference
Principles of Operation
SITRANS LR250 is a 2-wire 25 GHz pulse radar level transmitter for continuous monitoring
of liquids and slurries
1)
. Radar level measurement uses the time of flight principle to
determine distance to a material surface. The device transmits a signal and waits for the
return echo. The transit time is directly proportional to the distance from 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).
Electromagnetic wave propagation is virtually unaffected by temperature or pressure
changes, or by changes in the vapor levels inside a vessel. Electromagnetic waves are
not attenuated by dust.
SITRANS LR250 consists of an enclosed electronic circuit coupled to an antenna and
process connection. The electronic circuit generates a radar signal (25 GHz) that is
directed to the horn.
The signal is emitted from the horn, 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 sensor reference point
2)
. This distance is used as a basis for the display of material
level and mA output.
Echo Processing
Process Intelligence
The signal processing technology embedded in Siemens radar level devices is known as
Process Intelligence.
Process intelligence provides high measurement reliability regardless of the dynamically
changing conditions within the vessel being monitored. The embedded Process
Intelligence dynamically adjusts to the constantly changing material surfaces within
these vessels.
Note: Where a number follows the parameter name (for example, Algorithm (2.8.4.1.)
this is the parameter access number via the handheld programmer. See
Parameter
Reference
on page 78 for a complete list of parameters.
1)
The microwave output level is significantly less than that emitted from cellular
phones.
2)
See
Dimensions
on page 12 and
Flanged Horn with extension
on page 14.