Liebert CHALLENGER 3000, Operation And Maintenance Manual

Page: 19 / 76

Operation with Advanced Microprocessor Controls
11
Analog Setup
For installation of analog sensors, see 4.5.1 - Connecting the Analog Sensors .
After selecting a compatible sensor and properly wiring it to the terminals, set up the control to mon-
itor the sensor as follows:
Slope —The slope is a multiplier used to scale the input signal. The slope can be positive (rising) or
negative (falling) and can range from 0 (resulting in a horizontal line) to ±999. The slope for a 0-5 volt
input is per 1 volt input, for 0-10 volt input is per 2 volt input, and for 4-20 mA is per 4 mA input. For
example, assuming an intercept of 0, for a 0-10 volt sensor input with a slope of 50, an input of 1 volt
would be displayed as 25: 1x(50/2); 2 volts would be 50: 2x(50/2); 3 volts would be 75: 3x(50/2); etc.
Intercept —The intercept is an offset from point 0 corresponding to 0 volts or 0 mA input. The inter-
cept can be positive or negative and can be a point from 0 to ±999.
Adding an intercept of 100 to the slope example above, 1 volt would be 125: 100 + (1x[50/2]); 2 volts
would be 150: 100 + (2x[50/2]); 3 volts would be 175: 100 + (3x[50/2]); etc.
Text —You may enter a custom label for each analog input. The text label can be 20 characters in
length including any of the following:
ABCDEFGHIJKLMNOPQRSTUVWXYZ#%*-0123456789, or space.
Set Status Display
The Status Display can be set to display the return air temperature and humidity SENSOR READ-
INGS or the temperature and humidity control SETPOINTS through this selection. When SET-
POINTS is selected, the status display indicates so by displaying “SETPTS.” If SENSOR READINGS
is selected, the Status Display will show the return air sensor readings.
Calibrate Actuator
For systems that use a valve actuator for chilled water or GLYCOOL cooling, the actuator timing may
be calibrated or adjusted. This is the time it takes for the valve to travel from full closed to full open.
It is programmable from 0 to 255 seconds. The factory default time is 165 seconds and should not be
changed unless the actual valve travel time is not correct. The full valve travel time is used by the
control to determine the appropriate valve position. For example, if the valve travel time is 165 sec-
onds and 50% cooling is being called for, the valve will open for 83 seconds to acheive 50% open. To
change the valve travel time, first enter the “CALIBRATE ACTUATOR” screen. The display will show
the present period used by the control for valve actuator full travel. Press ENTER and adjust the time
using the UP/DOWN arrows. When the correct time is displayed, press ENTER to store the new time
to memory.
NOTE
For a 4-20 mA input sensor, if the desired reading at 4 mA input is 0, then an intercept of
-1 x slope would be required. For example, assuming a slope of 50, the formula would be
([-1 x 50] + 4 x [50/4]) = 0. The intercept is -50.