A C-TRAC3
20 of 21 Jan 13 R5
Air Quality Sensors
Generally these sensors output a modulating 0-10Vdc signal based on the levels of impurities in the air.
The signal is connected to the MP terminal on the C-TRAC3 to override the base minimum position.
Normally the minimum position pot located on the face of the C-TRAC3 sets the base minimum. Note that
here are additional connection methods that can achieve the same result. Check with the wiring diagram,
terminal designation sheet and unit function sheet.
Damper Linearization Curve
As a set of dampers open, the amount of static pressure drop decreases. However it does not decrease
proportionally. Because of this the C-TRAC3 uses an output curve to the damper actuator(s) that tries to
match the actual airflow with the required airflow. For example, an input signal of 1.5Vdc (15%) will
output 1.9Vdc to the actuator. The actual air flow will be near 15%.
EMS Control
Energy Management Systems incorporating BACnet or Modbus communication protocols, or a nearby
computer using Engineered Air SMC software, may be connected to the C-TRAC3 for remote monitoring
and control of temperature setpoints, minimum damper positions and enabling operational modes and
control. Review the associated manual supplied with the equipment for additional information.
Face Mounted Setpoints
Some applications do not require the use of one or both of the setpoint knobs mounted on the face of the
C-TRAC3. If not required, the ‘Not Used’ check box will be ticked, with the note ‘Set at Max’ below it.
Setting the knob below maximum may cause the C-TRAC3 to have higher than expected setpoints.
Multizone Setpoint Calculation
Multizone program setpoints are configured somewhat differently from other programs. The SMC
software allows the user to input the minimum and maximum cold deck temperatures, and the maximum
hot deck temperature. The minimum hot deck temperature is based on an adder to the minimum cold
C-TRAC3 Damper Linearization Curve
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C-TRAC3 Output
Linear Output
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