MODEL 54eA | SECTION 15.0 |
| CALIBRATION - CONTROL |
concentration, temperature) compared to the measurement range, the difference between the 20 mA (Hi) and 4 (or 0) mA (Lo) setpoints, which you determined when configuring the analog output.
In the example shown in Figure
The percent change in pH was:
pH2 - pH1 |
| x 100% = | 8.2 - 7.2 pH | = 33.3% | |
pH “Hi” - pH “Lo” | 9.0 - 6.0 pH | ||||
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The change in the output signal was:
6 - 4 milliamps x 100% = 12.5%
20 - 4
So the Plant Gain is:
C = 33.3 = 2.66 12.5
Once R and C are calculated, the proportional and integral bands can be determined as follows:
C
Proportional band (%) = P = 286 R
Integral Time (seconds per repeat) = I = 3.33 x D x C
So for the example:
286 (2.66)
P = = 254% 3
I = 3.33 (4 sec.) 2.66 = 36 seconds
To enter these parameters, use the procedure detailed in Section 5.6.
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