Airflow Measuring Systems; Traq™ Dampers - Trane Performance Climate Changer PSCA Installation, Operation And Maintenance Manual

Airflow Measuring Systems

Traq™ Dampers
Traq dampers are low-leak dampers that modulate and
measure airflow. Each Traq damper section is supplied
with a factory-mounted ventilation control module (VCM)
on the interior of the mixing box section. The VCM has an
input terminal for power and an output terminal for air
velocity (see Figure 84). A direct-digital controller controls
the factory-mounted and wired actuators.
Figure 84. Traq damper terminal connections
Velocity (2-10 Vdc)
GND
24 Vac
GND
Thermistor
Figure 85. Traq damper terminal connections
VCM (Transducer) Calibration.
zero function that recalibrates the transducer once every
minute. When troubleshooting, allow for the recalibration
time before making any measurements.
Input Power.
The only input the VCM needs is the 24 Vac
power connected to the J2 plug (green and black wires).
Output Velocity Signal.
signal from the VCM represents air velocity. This voltage
CLCH-SVX013B-EN
Ventilation Control Module
J4 (Red)
J4 (White)
J2 (Black)
J2 (Green)
J5 (Yellow)
J5 (White)
The VCM has an auto-
The 2 to 10 Vdc linear output
can be converted to represent airflow (cfm or L/s) using the
formula below and Table
Airflow = k (cfm @ 10V)
or
Airflow = k (L/s @ 10V)
For example, if the VCM on a size 30 air handler at sea
level (k=1) has a 10-volt signal, it would represent
24,492 cfm (11,559 L/s) through the Traq damper. If
the voltage were 6 volts, airflow through the Traq
damper would be 12,246 cfm (5779 L/s).
Table 13. Altitude adjustment factors
Sea level = 1.0
Elevation (feet)
1000
2000
3000
4000
5000
6000
7000
8000
9000
10,000
In Table 14, the cfm at 10Vdc is a calculated value based on
area and peak velocity. In certain situations, it can be
advantageous to raise the velocity of air through the
remaining Traq dampers by closing off one or more
dampers in the unit. The cfm at 10Vdc can be recalculated
based on the proportion of remaining Traq dampers or by
multiplying the remaining area of dampers by peak
velocity. Calculations are based on VCM voltage versus
airflow at sea level.
Start-Up
13.
 volts 2 
–
------------------------------
8
 volts 2 
–
------------------------------
8
k
0.982
0.964
0.949
0.930
0.914
0.897
0.876
0.860
0.846
0.825
67