Trane Tracer VV550 Installation, Operation And Maintenance Manual page 17

Table 10.Flow sensor loss impact depends on control algorithm configuration
Airflow sensor Type of
failure control
• Open or shorted Space
after being valid; temperature
control
• Cannot calibrate;
• Measured airflow Ventilation flow
more than 120%. control
Flow tracking
When the communicated airflow setpoint is invalid, either the flow sensor has failed or
calibration has failed, and the controller closes the air valve if the configured airflow
tracking offset is negative. If the configured airflow tracking offset is positive, the
controller opens the air valve to the configured maximum airflow.
Once a valid differential pressure is established through the local hardwired input and
then is no longer present, the controller generates a flow sensor failure diagnostic.
This sequence is ignored by and can be overridden by the following sequences listed in
priority from highest to lowest. For control sequence descriptions, refer to
Sequences," p.
1. Power-up/reset sequence (highest priority);
2. Manufacturing test;
3. Unit shutdown;
4. Emergency override;
5. Manual output test;
6. Auto commission;
7. Water valve override.
CNT-SVX17G-EN
Unit operation
Pressure dependent
mode; airflow sensor
failure diagnostic
Pressure dependent
mode; airflow sensor
failure diagnostic
Airflow failure mode;
airflow sensor failure
diagnostic
8.
Air valve operation
Normal
Normal
If the configured airflow
tracking offset is
negative, close the air
valve. If the configured
airflow tracking is offset is
positive, move the air
valve to the configured
minimum airflow.
Inputs and Outputs
Fan Reheat
Normal Normal
Do not Normal
care
Do not Do not
care care
"Control
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