BA 4510
1.4.3.2 Solid Electrolyte Measuring Cell Design Principle
1
Ceramic tube
2
Ceramic cover for the reference electrode
3
Measuring electrode
4
Reference electrode
5
Thermocouple
6
Reference electrode connecting wire
7
Measuring electrode connecting wire
The measuring cell is a zirconium dioxide ceramic tube with two electrodes made from platinum wire. Inside the tube the
sample gas flows through is the measuring electrode. The electrode outside of the tube serves as reference electrode with con-
stant electrode potential. The electrodes and the ceramic tube from a voltaic cell (solid electrolyte measuring cell).
For favourable oxide ions conductivity values of the zirconium dioxides and prevent interference reactions due to unbalance
with flammable components in the sample gas, the measuring cell is heated to 750 °C. A thermocouple on the measuring cell de-
termines the current measuring temperature T. An electronic control circuit ensures a constant measuring temperature.
CAUTION
Risk of overheating
Overheating will damage the device.
Heating results in heat loss in the inert gas measuring device. Therefore do not place
items on or in close proximity of the device.
The block diagram in the next chapter how measurements are processed electronically.
1.4.3.3 Electronic Processing of Measurements
The following block diagram outlines how signals are processed.
Measuring cell
Cell voltage
amplifier
Thermovoltage
amplifier
On-screen
keyboard
Heater
control
Microcontroller
Power
supply
0.8 A (resettable)
1.0 A
100...24 0V AC, 47...63 Hz
Relay output
RS232
Analog output
Measuring cell monitor
Fig. 2: BA 4510 block diagram
5
Bühler Technologies GmbH
BE550013 ◦ 09/2018
