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10.11.1
Timed Cycling:
Note: Special Control for Feed type relay. These
instructions work with relays 1 – 5. These
instructions work with relays 6 – 9 when they are in
ON/OFF mode.
Often there is a long time delay between adding a
chemical and measuring its effect at a sensor. This
causes set-point overshoot and poor control.
Examples: Pumping acid into a large process tank
or adding bleach to a cooling system with a large
sump volume.
Timed Cycling feeds for a user defined ON Time
then waits for a user defined time before feeding
again, allowing the system to respond to the fed
chemical. During the ON Time, ON-OFF pumps and
frequency controlled pumps feed on set-point
control.
The On Time and Period are adjustable. The Off
Time is the difference between the two.
If the Period is 50 seconds and the On Time is 10
seconds, the Off Time will be 40 seconds.
The 'Chemical 123'Diagnostic display counts down
the time in the ON Time and OFF Period.
Selecting a Special Control automatically sets
typical default times or sensor values.
Adjust the default values for your site's application.
1. To Set and adjust the Timed Cycling press
MENU
2. Scroll to the I/O Setup selection and press
OK
3. Scroll to select the desired relay (2:Chlorine
Pump) and press OK
4. Scroll to Special Control and press OK
5. Scroll to Timed Cycling and press F1
6. Use Up/Down and Left/Right Arrow keys to
Edit the Period value then press F2. In this
example the default 900 second Period.
7. Use Up/Down and Left/Right Arrow keys to
Edit the ON Time then press F2. In this
example the default is 120 second ON
Time.
8. Relay 2 is now ON for 120 seconds and
OFF for 780 seconds in each 900 second
Period.
9. Press ESC Escape to save and exit.
SPECIAL CONTROL TIP:
When using Timed Cycling, Time
Modulate or PID control, best results for
tuning the loop are achieved if you only
change one variable at a time and wait for
two or three cycles to observe the effect
of this change. This would include
changing the stroke % of the pump and
any setting in the special control program.
10.11.2
Note1:Time Modulate is a Special Controls selection
for Feed type relay
Note2: Relays P6-P9 must be set to ON/OFF
Mode
Time modulate has adjustable turn on and turn off
set-points, a period and a direction, Increasing or
Decreasing the variable. Example of Increasing: A
chlorine pump will increase the ORP reading.
Example of Decreasing: A blowdown valve will
decrease conductivity.
When using Time Modulate on an increasing control
loop, the Turn On set-point will be lower than the
Turn Off set-point. When the ORP is below the Turn
On set-point, the output relay is on constantly. When
ORP is above the Turn Off set-point, the output relay
is off constantly. In either case, Time Modulate is not
operating until the ORP is between the set-points. It
is on in proportion to the ORP value with respect to
the range between the set-points.
Example: Period=100 seconds, ORP Turn ON set-
point = 400mV and ORP Turn OFF set-point =
500mV, current ORP = 450mV. 450mV is half way
between 400 and 500 so the pump will be on for
50% of the period time or in this example 100 x 50%
= 50 seconds and off for 50% or 50 seconds.
If the ORP drops to 430, the pump will be on for
70% and off for 30% of the 100 second period.
Time Modulate works for both increasing and
decreasing control loops.
1. To Set and adjust the Time Modulate press
MENU
2. Scroll to the I/O Setup selection and press OK
3. Scroll to select the desired relay (2:Chlorine
Page 77 of 102
Programming the Outputs
Time Modulate
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