West Control Solutions TB 45 Temperature Monitor - Manual (Page 25)

6.4 Filter
A first order mathematic filter can be used for the input values. The time constant is adjustable. This low-pass filter is
used for suppression of process-dependent interference on the input leads. The higher the value, the better the filter
effect, but the longer the input signal delay.
a
Please, note that the adjusted filter time t.F1 can increase the response time for the process value. The
DIN-tested response times were tested with t.F1 = 0,5 s.
6.5 O
2
measurement (optional)
This function is available only on versions with a second universal input INP2.
Lambda probes ( probes) are used as input signals. The electromotive force (in volt) delivered by lambda probes is de-
pendent on the instantaneous oxygen content and on the temperature. Therefore, the device can only display accurate
measurement results, if the probe temperature is known.
The unit calculates the oxygen content using the Nernst formula.
Distinction of heated and non-heated lambda probes is made.
The two sensor types can be processed by the unit.
Heated lambda probes
Heated probes are fitted with a controlled heating, which ensures a continuous temperature. This temperature must
be specified in parameter Probe temperature in transmitter CI 45.
Parameters
Functions Pro be temperature t EmP ...°C (/°F/K - dependent on configuration)
Non-heated lambda probes
When the probe is always operated at a fixed, known temperature, the procedure is as with a heated probe.
A non-heated
probe is used, if the temperature is not constant. In this case, the temperature in addition to the
probe mV value must be measured. For this purpose, any temperature measurement with analog input INP2 can be
used. During function selection, input INP2 must be set for measurement (
CONF/InP.2/I.Fnc=1).
Configuration:
O
2
-measurement must be adjusted in function 1 :
Func r Fnc.1
7
O2-measurement with constant probe
temperature (heated probe)
8
O2-measurement with probe temperature
measurement (non-heated probe)
Connection
Connect the input for the lambda probe to INP1 . Use terminals I and 2.
If necessary, temperature measurement is connected to INP2.
Input 1 is used to adjust one of the high-impedance voltage inputs as sensor type:
Inp.1r S.tYP
41 Special ( -2,5...115 mV)
42 Special ( -25...1150 mV)
43 Special ( -25...90 mV)
44 Special ( -500...500 mV)
47 Special ( -200...200 mV)
These high-impedance inputs are without break monitoring. If necessary, input signal monitoring is possible via the
limit values.
g
Input 1 must be operated without linearization:
Inp.1r S.Lin 0 no linearization
Functions
TB 45 Filter 25