Specifications

86 Catalog WSC/WDC-4
In addition to the trended items above, other real-time operating parameters are also shown
on the touchscreen. These items can be displayed in two ways: by chiller graphic showing
each component or from a color-coded, bar chart format. At a minimum, the following
critical areas must be monitored:
• Oil sump temperature
• Oil feed line temperature
• Evaporator saturated refrigerant temperature
• Suction temperature
• Condenser saturated refrigerant temperature
• Discharge temperature
• Liquid line temperature
Complete unit operating instructions shall be viewable on the touchscreen and be
downloadable via an onboard USB port.
Complete fault history shall be displayed using an easy to decipher, color coded set of
messages that are date and time stamped. The last 20 faults shall be downloadable from
the USB port.
Automatic corrective action to reduce unnecessary cycling shall be accomplished through
pre-emptive control of low evaporator or high discharge pressure conditions to keep the
unit operating through ancillary transient conditions.
System specific, chiller plant architecture software shall be employed to display the chiller,
piping, pumps and cooling tower. Chiller plant optimization software for up to 3 chillers
shall also be included to provide automatic control of: evaporator and condenser pumps
(primary and standby), up to 4 stages of cooling tower fans and a cooling tower modulating
bypass valve and/or cooling tower fan variable frequency drives. There shall be five
possible tower control strategies:
• Tower fan staging only – up to 4 stages controlled by either the entering condenser
water temperature or lift differential temperature between the condenser and
evaporator saturated temperatures.
• Tower fan staging plus low limit - controlled as in # 1 plus tower bypass valve set at a
minimum entering condenser water temperature
• Tower staging with staged bypass control – similar to # 2 with additional control of the
bypass valve between fan staging to smooth control and minimize fan staging.
• VFD staging only – in this mode, a variable speed drive controls the first fan with up
to 3 more fans to be staged on and off and there is no bypass valve.
• VFD and Valve Staging – same as # 4 plus bypass valve control
Factory mounted DDC controllers shall support operation on a BACnet, Modbus or
LONWORKS network a factory-installed communication module.
Factory mounted DDC controller(s) shall support operation on a BACnet®,
Modbus® or LONMARKS ® network via one of the data link / physical layers listed
below as specified by the successful Building Automation System (BAS) supplier.
• BACnet MS/TP master (Clause 9)
• BACnet IP, (Annex J)
• BACnet ISO 8802-3, (Ethernet)
• LONMARKS FTT-10A. The unit controller shall be LONMARKS® certified.
The information communicated between the BAS and the factory mounted unit
controllers shall include the reading and writing of data to allow unit monitoring,
control and alarm notification as specified in the unit sequence of operation and the
unit points list.