Trane RTWD Installation Operation & Maintenance page 68

Communications Interface options
2) Analog voltage output is a function of refrigerant
differential pressure with the endpoints customer
defi ned in the Refrigerant Pressure Analog Output
settings - Refrigerant Differential Pressure Indication
The transfer function is 2 to 10 Vdc corresponding from
the "Differential Pressure Output Minimum Pressure"
setting to the "Differential Pressure Output Maximum
Pressure" setting. Both settings are confi guration
settings in the service tool. Since the calculations relate
to pressure differences, they can be made in either
gauge or absolute as long as they are consistent. For
multiple circuit chillers, such as RTWD, the refrigerant
differential pressure used in the calculation will be the
lowest differential pressure of all of the running circuits.
If a given circuit's Condenser or Evaporator pressure
transducers that are invalid (i.e. non-communicative or
out of range) that circuit's DP will be excluded. Note:
If both circuits have at least one pressure transducer
invalid, then output shall 1.0 VDC (per the table below),
but if only one circuit has an invalid pressure transducer,
the opposite circuit's DP value shall be used for the
analog output.
Refrigerant Differential Pressure
Sensor(s) out of range
< Differential Pressure Output Minimum Pressure
Differential Pressure Output Minimum Pressure <=
Refrigerant Differential Pressure <=
Differential Pressure Output Maximum Pressure
> Differential Pressure Output Maximum Pressure
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For this feature:
Refrigerant Differential Pressure = Lowest of (condenser
refrigerant pressure ckt x - evaporator refrigerant
pressure ckt x)
The "Differential Pressure Output Minimum and
Maximum Pressure" confi guration settings are not
a negative number and the Refrigerant Differential
Pressure used in the calc shall be clamped to be never
less than zero.
The following equations are applied:
Refrigerant Differential Pressure Indication Output (Vdc)
Vdc = 1.0
Vdc = 2.0
8 * (Refrigerant Differential Pressure - Min Delta Pressure Calibration)
Vdc = 2 +
(Max Delta Pressure Calibration - Min Delta Pressure Calibration)
Vdc=10.0
RLC-SVX14H-GB