YOKOGAWA av550g, User Manual

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< 10. Other Functions >
10-3
IM 11M12D01-01E
10.1.7 Cell Response Time
The cell’s response time is obtained in the procedure shown in Figure 10.3. If only either a zero or
span calibration has been carried out, the response time will not be measured just as it will not be
measured in manual calibration.
mA
90%
100%
The response time is obtained after the corrected calibration curve has been found. The response time
is calculated, starting at the point corresponding to 10% of the analog output up to the point at 90% of
the analog output span. That is, this response time is a 10 to 90% response.
10% of analog
output span
Five minutes maximum
Response time
Start calibration
Time
Calibration
complete
F10-3E.ai
Figure 10.3 Typical response time characteristic
10.1.8 Robustness of a Cell
The robustness of a cell is an index for predicting the remaining life of a sensor and is expressed as
one of four time periods during which the cell may still be used:
(1) more than a year
(2) more than six months
(3) more than three months
(4) less than one month
The above four time periods are tentative and only used for preventive maintenance, not for warranty
of the performance.
This cell’s robustness can be found by a total evaluation of data involving the response time, the
cell’s internal resistance, and calibration factor. However, if a zero or span calibration was not made,
the response time cannot be measured. In such a case, the response time is not used as a factor in
evaluating the cell’s robustness.
10.1.9 Cell’s Internal Resistance
A new cell (sensor) has an internal resistance of 200Ω maximum. As the cell degrades, so will the
cell’s internal resistance increase. The degradation of the cell cannot be evaluated just by changes in
cell’s internal resistance, however. Those changes in the cell’s internal resistance are just a guide to
the extent the cell is degrading. The updated values obtained during the calibration are displayed.