MICROTSCM (07/09)
Page 17
REV 2.4
Convert the effected change in SCU to a percentage. Since the instrument always operates
in a range of +10 SCU to -10 SCU, the range is 20 SCU.
% effect = Effect X
100
Range
1
Then calculate the proportion band or PB.
PB = % Effect
X
100
% Cause
1
In our
example
calculating the Proportional Band or P. Band with a 10% change (cause)
:
% effect =
0.5 SCU X
100 = 2.5%
20.0 SCU 1
PB = 2.5%
X
100
= 25%
10%
1
To prevent overshoot, it is desirable to slow the control loop down a little more. To do this
the PB is multiplied by 1.5.
In our
example
:
PB = 25% X 1.5
≈
38%
Once the control parameters are set into the analyzer and the dosing pump has been set,
the SP may need to be adjusted to account for seasonal change, but other than routine
maintenance and monitoring, no other adjustments should be required.
7.3.2 Entering the Control Parameters
The next step is to enter the control parameters into the MicroTSCM analyzer. To do this,
follow the steps:
1.
Press
/Menu
to enter the Main Menu screen.
2.
Press
F1 (Sensor Setup)
to enter the Sensor Setup screen.
3.
Press
F4 (Extended Setup)
to enter the Extended Setup screen.
4.
Press
F2 (PID Analyzer)
to enter the PID Analyzer screen.
5.
At
F1 (Mode)
toggle the highlighted setting to AUTO using the
ST
buttons.
6.
Press
F3 (Set Point)
adjust the Set Point (from section 7.1) using the
ST
buttons.
7.
Press
F4 (P. BAND)
adjust value using the
ST
buttons (in our example 38.00).
8.
Press
F4
again
(INT. TIME)
adjust value using the
ST
buttons (in our example 100).
9.
Press
/Menu
four times to return to the graphic monitoring screen.
7.3.3 Manual Control
To operate the system in manual mode, follow the steps 1-4 above, on step 5 use the
ST
buttons to adjust the setting to MANUAL. Select F2 and a new setting called
MANUAL OVERRIDE will show. Adjust the value using the
ST
buttons. A +10 will
increase the pump speed by 10% and -10 will decrease pump speed by 10%. Please note
that the speed change may not be representative of dosing rate.
