OPERATION
Page 32
MANUAL
CT
Controllers
1 - CONDUCTIVITY MAIN MENU
Conductivity and TDS
The Conductivity sensor is used to monitor and control the
concentration of Total Dissolved Solids (TDS) in the water. It
reads the conductivity of the water in microsiemens per
centimeter (
µ
S/cm). The conductivity readings can be
converted into ppm or mg/l of TDS by using a conversion factor
that depends on the type of ionic species that are present in
the water. Normally, a conversion factor of 0.5 is used for
water solutions containing different species of carbonate and
chloride ions (see 1.8 - Select Scale).
Control of Conductivity or TDS is obtained by replacing the
water with fresh water when the concentration level gets too
high. This is done by opening a valve to dump the water.
Replacement with fresh water is done automatically by opening
the valve through the water level control option.
Both flows of water - in and out - can be monitored with the
flowmeter option.
Conductivity or TDS Display
Depending on the application, it may be customary to control
either conductivity or TDS. The display is therefore available in
the two systems, as shown on the sample screens.
Changing the displays from conductivity to TDS is done by
changing the TDS factor from 1 to any other value different
from 1. To do this, select the SELECT SCALE Submenu (see
1.8 and 1.8.2) and change the TDS factor value. If the TDS
Factor is 1, the display shows Conductivity in
µ
S/cm. If it is
different from 1, it shows TDS in ppm or mg/l.
1.1- Control Mode
Line 1 shows the Control mode that is currently selected: OFF
(X), Manual (M), AUTO (A), Cycle Timer (T), Percent of Flow
(F), Daily Schedule (S) or 2-Week Schedule (B).
To change the Control Mode, select the first line with the UP or
DOWN ARROW keys and press the RIGHT ARROW key. The
Control Mode screen is then displayed.
The Control Mode screen and selection procedures are
common to all control functions. See CONTROL Submenu in
this Chapter.
1.2 - Display and Calibration
The second line displays the current reading of conductivity in
µ
S/cm or TDS in ppm or mg/l.
The conductivity or TDS readings should be calibrated with
standard test solutions and with temperature compensation
activated on the controller.
As with all sensor calibrations, the conductivity sensor can be
calibrated with 1, 2 or 3-Point calibration for origin, slope and
curvature. This is done by pressing the RIGHT ARROW key to
enter the CALIBRATION Submenu. The calibration procedure
is common to all control functions. See CALIBRATION
Submenu further down in Chapter II.
Menu 1
Menu 1 (Alternate)
Submenu 1.2.1
1.2.1 Temperature Compensation
After calibration, the Compensation Submenu 1.2.1 is
displayed. This feature requires the use of the temperature
sensor. The correction is expressed as a change of slope per
degree Celsius at 25oC. The default is 2%, but it can be
adjusted if necessary.
1.3 - Setpoint
The SETPOINT determines the conductivity or TDS level that
will trigger the dumping (bleeding) of water when the controller
when placed in the AUTO control mode.
To change the setpoint, press the RIGHT ARROW key and
enter the numerical value with the digital keypad.
CONDUCTIVITY
AUTO
Calibrate
uS
1500
Setpoint
uS
2500
Alarm Low
uS
100
Alarm High
uS
5000
Time Limit
min
30
Run Time
15
60
Select Scale
TDS
AUTO
Calibrate
ppm
750
Setpoint
ppm
1250
Alarm Low
ppm
50
Alarm High
ppm
2500
Time Limit
min
30
Run Time
15
60
Select Scale
Use Automatic
Temperature Compensation
for Conductivity?
NO
YES
