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Power Calculations
The power calculations start from the physical value,
Power, from the compressors – a totalized instantaneous
power from all compressors in the chiller. This value is
integrated over an hour period to provide Hourly Usage.
The Hourly Usage value is totalized daily for the data
logging report (resets at midnight) into Daily Usage
variable.
Also at midnight it adds up to both monthly variable
Monthly Usage and total variable Total Usage. Monthly
st
Usage resets on the 1
day of the month at midnight.
Total Usage however does not reset ever unless button
Reset kWh is pressed. This button is available at Main
Menu > Settings Menu > HMI > Admin Parameters and
can be accessed by Admin user only.
Beside the Total Usage variable there is the date which
indicates when Total Usage kWh count started. When Total
Usage kWh count starts over after being reset, the date
updates as well.
Tonnage
To display tonnage and flow:
1. Navigate to HMI Configuration screen.
2. Change Flow Metering mode to one of the options
shown below. This will display corresponding controls
on Chiller Control screen.
Figure 20. Flow metering
3. Flow Metering source options:
a. User Entered – Provides Chiller Flow Rate data
entry on the Chiller Control screen. Enter a
theoretical flow value for the chiller.
Figure 21. Chiller flow rate
Note: The tonnage display will also reflect this
theoretical value.
b. Flow Meter – relies on Main PLC analog input to
have a calibrated flow rate for the chiller.
Enter the Flow Meter Maximum value on the Chiller
Control Screen.
Figure 22. Flow meter maximum
c. Differential Pressure– relies on 2 pressure sensors;
one inlet and one outlet connected to Main PLC.
ARTC-SVX013A-EN
Provides the following additional fields:
•
Nominal flow – enter the design 100% load flow
rate.
•
Nominal Differential pressure – enter the DP
reading for 100% design flow rate.
•
Evaporator Flow Threshold – enter minimum
value of DP that is considered a flow proof.
•
Actual DP displays the difference between
Entering and Leaving fluid pressures.
•
Actual Flow displays the results of the internal
calculation based on measured DP.
4. Enter Fluid Compensation Factor on the Chiller Control
screen if the fluid used is not water.
Metric/Imperial Display
The System allows you to customize your display to suit
your environment. Whether you prefer to see data in
imperial or metric units, it is a single click of a button:
1. Navigate to the HMI Configuration screen – Main Menu
> Settings Menu > HMI.
2. Toggle the Display Imperial button. Button displays
current setting.
Figure 23. Display imperial button
BMS Interconnectivity
Chiller system includes a standard building system
interface that has a comprehensive set of data points,
status, alarms, and faults. This section outlines our
standard list protocols, a definition of the special functions
available, a note on default configuration, and a complete
data list for our interface.
The device is a FieldServer Protonode from MSA Safety
with Trane-specific configuration.
Protocols
The chiller control system supports the following BMS
communication protocols.
•
Modbus RTU
•
Modbus IP
•
BACnet MS/TP
•
BACnet IP
Operating Procedures
43
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