West Control Solutions N8800 - Manual (Page 70)

7.2 O
2
measurement
This function is available only on the instrument version with INP3.
As the O
2
-measurement result range can extend over many decades, automatic
display switch-over between “ % ” and “ppm“ was realized.
The instantaneous unit is displayed in
the lower line.
With set-point changing via keys I or
D, the unit of the set-point and of the
other parameters is displayed.
Lambda probes (λ probes) are used as
sensors.
The electromotive force (in Volts) generated by λ probes is dependent of
instantaneous oxygen content and temperature. Therefore, the 8800 process
controller can only evaluate exact measurement results, if it knows the sensor
temperature.
Distinction of heated and non-heated lambda probes is made. Both can be
evaluated by the 8800 process controller.
Heated lambda probes
Controlled heating which ensures constant temperature is integrated in the heated
λ probe. This temperature must be entered in the 8800 process controller
parameter Probe temperature.
Parameter r Controller r Probe temperature r .....°C (/°F - dependent of
configuration)
Cntr r tEmP temp. 0...9999
Non-heated lambda probes
With the probe always operated at a fixed, known temperature, a procedure as
used for a heated probe can be used.
A non-heated λ probe is used, unless the temperature is constant. In this case, the
probe temperature in addition to the probe mV value must be measured. For this
purpose, any temperature measurement with one of the analog inputs INP2 or
INP3 can be used. During function selection, the input must be set to X2 (second
process value).
7.2.1 Connection
Connect the input for the lambda probe to INP1.
Use terminals A15 and A17.
If necessary, temperature measurement must be connected to INP2 or INP3.
Special functions
O
2
measurement 70 8800 process controller