Trane RTWB Helical-Rotary Installation Operation & Maintenance page 24

24
Installation Electrical
External circuit lockout - Circuit
number 2
The UCM provides auxiliary control
of a customer-specified or -installed
contact closure, for individual
operation of circuit number 2. If the
contact is closed, the refrigerant
circuit will not operate. The
refrigerant circuit will run normally
when the contact is opened.
External circuit lockout will only
function if External Circuit Lockout
(service setting Menu) is enabled.
Connections are shown in the field
diagrams that are shipped with the
unit.
Ice-making option
Ice-machine control (Operator
Setting Menu) must be enabled. The
UCM provides auxiliary control for a
customer-specified or -installed
contact closure for ice making.
When contact 6S55, module A9,
terminals TB1 1 and 2, is provided,
the chiller will run normally when
the contact is open. Upon contact
closure, the UCM will initiate an ice-
building mode, in which the unit
runs fully loaded at all times. Ice-
building shall be determined either
by opening the contact or based on
the entering evaporator-water
temperature setting under Active Ice
Termination Setting (Chiller Report
Menu). The UCM will not permit ice-
building mode to be reentered until
the unit has been switched out of
ice-building mode (open 6S55
contacts) and then switched back
into ice-building mode.
Table 10: Input values vs. External chilled-water setpoint
Voltage (V (dc))
3.6
4.6
5.6
6.7
7.7
In ice-building, the current setpoint
will be set at 120%. For example, if
the front panel or external current
limit setpoint is set to 80%, in ice-
building the active current limit is
120%.
If, while in ice-building mode, the
unit gets down to the freezestat
setting (water or refrigerant), the
unit will shut down on a manually
resettable diagnostic, just as in
normal operation.
External chilled-water setpoint:
voltage source 2-10 V (dc), or Current
source 4-20 mA
This option allows the external
setting of the chilled-water setpoint,
independent of the front panel
chilled-water setpoint, by one of the
two means:
1 - An isolated voltage input 2-10 V
(dc)
2 - An isolated current loop input 4-
20 mA
Isolated 2-10 V (dc)voltage source
input
Set dip switch SW1-1 of the option
module A9 to "OFF . " Connect the
voltage source to terminals 4 (+) and
5 (-) on option module A9 TB1. CWS
is now based on the following
equation:
CW Setpoint °C = (V (dc) * 4.88) -
27.56
Sample values for CWS vs. V (dc)
signals are shown in Table 10.
Current (mA) Resulting chilled-water setpoint (°C)
7.2
9.2
11.3
13.3
15.4
-10
-5
0
5
10
RTWB-SVN01B-E4