Trane Tracer ZN.520

CNT-SVX04A-EN
Analog inputs
34
Outdoor air temperature
Analog input 3 (AI 3) is used for outdoor air temperature or alternatively as a
generic temperature input (10 kΩ thermistor only). When configured as an
outdoor air temperature input and when a valid outdoor air temperature exists
(either hardwired or communicated), the controller uses this value to determine
if economizing (free cooling) is feasible if the controller should enter freeze
avoidance during unoccupied periods.
If the outdoor air temperature is below the economizer enable point
(adjustable), then economizing is allowed. If the outdoor air temperature is not
present, then economizing is not allowed. If both the hardwired and
communicated outdoor air temperatures are present, the controller uses the
communicated value for control decisions. Once an outdoor air temperature
has been established (either hardwired or communicated), the controller
generates an Outdoor Air Temp Failure diagnostic if the signal is no longer
valid, and the unit disallows economizing.
A value of Enable or Disable for nviEconEnable overrides these decisions,
regardless of the presence of an outdoor air temperature value.
Economizing is disabled in the DX mode. Refer to“DX operation” on page 70.
Generic temperature input
Analog input 3 (AI 3) is normally used for outdoor air temperature or
alternatively as a generic temperature input (10 kΩ thermistor only). When
configured as a generic temperature input, the input can be used in a variety of
applications using Tracer Summit. This input has no effect on the controller’s
operation but will report a Generic Temperature Failure diagnostic message if
the input becomes invalid or out of range.
Universal 4–20 mA input
Analog input 4 (AI 4) can be configured for one of three functions. See Table 29.
Table 29 Use of Analog Input 4 as a universal 4–20 mA input
AI 4 configuration Range Application
Generic 4–20 mA 0–100% Useful only for Tracer Summit systems. There is no effect on the operation of
the controller.
Relative humidity 0–100% Measurement of RH for dehumidification control of the space. NOT to be used
for outdoor RH sensing.
CO
2
0–2000 ppm Useful only for Tracer Summit systems. There is no effect on the operation of
the controller.