Installation and Maintenance Manual

Installation Electrical
RTAE-SVX001B-EN 37
Upon contact opening, the refrigerant circuit will run
normally.This feature is used to restrict total chiller
operation, e.g. during emergency generator operations.
Connections to 1K3 are shown in the field diagrams that
are shipped with the unit.
These customer-supplied contact closures must be
compatible with 24 VDC, 12 mA resistive load. Silver or
gold plated contacts are recommended.
Ice Building Option
UC800 provides auxiliary control for a customer specified/
installed contact closure for ice building if so configured
and enabled.This output is known as the Ice Building
Status Relay. The normally open contact will be closed
when ice building is in progress and open when ice
building has been normally terminated either through Ice
Termination setpoint being reached or removal of the Ice
Building command.This output is for use with the ice
storage system equipment or controls (provided by
others) to signal the system changes required as the chiller
mode changes from “ice building” to “ice complete”.
When contact 5K36 is provided, the chiller will run
normally when the contact is open.
UC800 will accept either an isolated contact closure
(External Ice Building command) or a Remote
Communicated input (Tracer) to initiate and command the
Ice Building mode.
UC800 also provides a “Front Panel IceTermination
Setpoint”, settable throughTracer™TU, and adjustable
from 20 to 31°F (-6.7 to -0.5°C) in at least 1°F (1°C)
increments.
Note: When in the Ice Building mode, and the evaporator
entering water temperature drops below the ice
termination setpoint, the chiller terminates the Ice
Building mode and changes to the Ice Building
Complete Mode.
Tracer™TU must also be used to enable or disable Ice
Machine Control.This setting does not prevent theTracer
from commanding Ice Building mode.
Upon contact closure, the UC800 will initiate an ice
building mode, in which the unit runs fully loaded at all
times. Ice building shall be terminated either by opening
the contact or based on the entering evaporator water
temperature. UC800 will not permit the ice building mode
to be reentered until the unit has been switched out of ice
building mode (open 5K36 contacts) and then switched
back into ice building mode (close 5K36 contacts.)
In ice building, all limits (freeze avoidance, evaporator,
condenser, current) will be ignored. All safeties will be
enforced.
If, while in ice building mode, the unit gets down to the
freeze stat setting (water or refrigerant), the unit will shut
down on a manually resettable diagnostic, just as in
normal operation.
Connect leads from 5K36 to the proper terminals of 1K8.
Refer to the field diagrams which are shipped with the unit.
Silver or gold-plated contacts are recommended.These
customer furnished contacts must be compatible with 24
VDC, 12 mA resistive load.
External Chilled Water Setpoint (ECWS)
Option
The UC800 provides inputs that accept either 4-20 mA or
2-10 VDC signals to set the external chilled water setpoint
(ECWS).This is not a reset function.The input defines the
setpoint.This input is primarily used with generic BAS
(building automation systems).The chilled water setpoint
set via theTracer AdaptiView™TD7 or through digital
communication withTracer (Comm3).The arbitration of
the various chilled water setpoint sources is described in
the flow charts at the end of the section.
The chilled water setpoint may be changed from a remote
location by sending either a 2-10VDC or 4-20 mA signal to
the 1K14, terminals 5 and 6 LLID. 2-10 VDC and 4-20 mA
each correspond to a 10 to 65°F (-12 to 18°C) external
chilled water setpoint.
The following equations apply:
If the ECWS input develops an open or short, the LLID will
report either a very high or very low value back to the main
processor.This will generate an informational diagnostic
and the unit will default to using the Front Panel (TD7)
Chilled Water Setpoint.
TracerTU ServiceTool is used to set the input signal type
from the factory default of 2-10 VDC to that of 4-20 mA.
TracerTU is also used to install or remove the External
ChilledWater Setpoint option as well as a means to enable
and disable ECWS.
External Demand Limit Setpoint (EDLS)
Option
Similar to the above, the UC800 also provides for an
optional External Demand Limit Setpoint that will accept
either a 2-10 VDC (default) or a 4-20 mA signal.The
Demand Limit Setting can also be set via the Tracer
AdaptiView™TD7 or through digital communication with
NOTICE:
Equipment Damage!
Freeze inhibitor must be adequate for the leaving water
temperature. Failure to do so will result in damage to
system components.
Voltage Signal
As generated from external source VDC=0.1455*(ECWS) + 0.5454
As processed by UC800 ECWS=6.875*(VDC) - 3.75
Current Signal
As generated from external source mA=0.2909(ECWS) + 1.0909
As processed by UC800 ECWS=3.4375(mA) - 3.75