Clean system – LSU 4.9 for industrial applications
LSU: Universally applicable
- The LSU wide-band lambda sensor is a planar ZrO₂ dual-cell limit-current sensor with integrated heater.
- It is used for measuring the oxygen content and the λ-value of exhaust gases in vehicle engines
- Thanks to a steady characteristic curve in the range λ = 0.65 to air, it is universally applicable for λ = 1 and for other λ-ranges.
LSU wide-band lambda sensor
As a planar ZrO₂ dual-cell limit-current sensor, LSU is used for measuring the oxygen content and the λ-value of exhaust gases of gasoline and diesel engines. Its heater is already integrated. LSU can be used for both λ = 1 and for other λ-ranges. A trimming resistor determining thesensor characteristics is installed at the connection-plug module. For its operation, special electronics (e.g. AWS off-value controller, LA4 or IC CJ125 evaluation circuit) are required.
It is made up of a Nernst-type potentiometric oxygen-concentration cell and an amperometric oxygen pump cell. When subject to high temperatures, oxygen ions diffuse through the Nernst-cell ceramics – as soon as there are differences in the partial oxygen pressure at both ends of the ceramics. The transport of ions results in an electrical voltage, which is measured using electrodes.
The components of the exhaust gas diffuse through the diffusion duct to the electrodes of the pump and Nernst cells, where they lead to a thermodynamic balance. Control electronics record the Nernst voltage and supply the pump cell with voltage. In case of a Nernst voltage of less than 450 mV, the exhaust gas is lean. Accordingly, the pump cell is supplied with a current that causes oxygen to be pumped out of the duct. By contrast,the exhaust gas is rich, if the Nernst voltage exceeds 450 mV. In this case, the control electronics reverse the voltage causing the cell to pump oxygen into the duct. An integrated (CJ125) component analyzes the signals. It includes the controller for thepump flow,the controller that keeps the Nernst cell at 450 mV and an amplifier.
The sensor element is manufactured using thick-film techniques. Due to production distribution, the characteristic curves for differentsensors will vary as well. Despite a uniform 0 V output voltage at an oxygen concentration of 0%, at air the voltage scatters between approx. 6 and 8 V. Each sensor is calibrated individually in order to establish a clear relationship between the measuredoxygen concentration and the output voltage. Calibration is recommended at each maintenance.
Fields of application:
- Gasoline engines
- Gas engines
- Diesel engines
- Lean-combustion engines
- Block-type thermal power stations
- Tempering furnaces
- Chemical industry
- Packaging equipment
- Process engineering
- Drying plants
Measurement and analysis processes
- Flue gas measurement
- Gas analysis
- Determination of Wobbe index
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