Primary Air Temperature/Discharge Air Temperature Analog Input - Trane Tracer VV550 Installation, Operation And Maintenance Manual

Primary Air Temperature/Discharge Air temperature Analog Input

The controller senses the primary or discharge air temperature input with a hardwired
10k thermistor. The primary/discharge air temperature analog input can be configured
as either primary air temperature or discharge air temperature and applied as:
•
•
Either configuration also provides monitoring and diagnostics.
The controller can receive the primary air temperature as either a local analog input or
as a communicated value. If both are present, the controller uses the communicated
source temperature. If neither is present, the controller uses configuration to assume a
primary air condition, either hot or cold.
The space temp controller or a flow-tracking controller can operate without a valid
discharge air temperature analog input.
temperature loss depends on the control algorithm configuration. If a valid discharge air
temperature is present, then disappears, then returns to the valid range, the controller
automatically resets and attempts to run normally.
Table 9. Discharge air temperature loss impact and control algorithm configuration
Discharge air Type of control
temperature
failure
Open or short Space
after being valid temperature
controller
Ventilation flow
controller with
reheat
Ventilation flow
controller without
reheat
Flow tracking
controller
This sequence is ignored by and can be overridden by the following sequences listed in
priority from highest to lowest. For more information on control sequence descriptions,
refer to
1. Power up and reset sequence (highest priority)
2. Manufacturing test
3. Unit shutdown
4. Emergency override
CNT-SVX17G-EN
Primary supply air temperature input for stand-alone changeover control and local
reheat lockout. The 10k thermistor is upstream from the VAV heating and cooling
capacity;
Discharge air temperature input for reheat control (preconditioning outdoor air in a
ventilation flow control job). The discharge air temperature is used as feedback to the
control algorithm that is influencing the discharge air temperature. This is discharge
air control for units configured as ventilation flow control units. The 10k thermistor
is downstream of the VAV reheat capacity.
Unit operation
Normal operation; discharge air
temperature failure diagnostic
Shutdown; discharge air temperature
failure diagnostic
Normal operation; discharge air
temperature failure diagnostic
Normal operation; discharge air
temperature failure diagnostic
"Control Sequences," p.
Table 9 shows that the impact of discharge air
Air valve
Normal
Closed
Normal
Normal
8.
Inputs and Outputs
Fan Reheat
Normal Normal
Do not Off
care
Do not Do not
care care
Do not Do not
care care
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