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If the probe reading is off by more than 50%, then the controller will indicate an error by displaying ‘CAL LIM µS‘.
This generally means that the probe has failed or needs cleaning.
Alternately, a sample of cooling tower water may be analyzed by a precalibrated conductivity monitor, and the DC4000
controller calibrated to match that reading using the sample as a standard solution.
The DC4000 Controller provides a circuit board test-switch to aid in troubleshooting the unit and system. The switch
is located under the access cover on the lower section of the controller (see Figure 10).
The conductivity test-switch allows the user to determine if the conductivity circuit is operating correctly. When placed
in the test position, this switch switches the conductivity probe and wiring out of the circuit and places an internal preci-
sion resistor. This resistor has a known conductivity reading of 3000 µS +/- 5%. If the unit has been calibrated then this
reading could be displayed as + or - 50% of this 3000 µS value (+4500 µS, -1500 µS).
COND : (
µS)3400
CAL: ( µS) 3400
From Conductivity Screen....press Enter....to Calibrate
In Calibration....
1) press
or
to adjust conductivity reading value
2) press to save calibrated conductivity value
Figure 10: Test Switch
ENTER
ENTER
(866) 433-6682 • (281) 359-8538 • [email protected] • www.novatech-usa.com
