RTAD-SVX01F-E4
55
Installation - Electrical
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
the remote contact connected to the
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. 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
(CWS), independent of the front
panel chilled-water setpoint, by one
of two means:
1 - An isolated voltage input 2-10 V
(dc)
2 - An isolated current loop input
4-20 mA
Note: For Free-Cooling units, this
option will be available only in
Compressor mode.
Isolated 2-10 V (dc) voltage source
input
Set dipswitch 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:
CWS °C = (V (dc) * 4.51) - 26.83
Sample values for CWS vs. V (dc)
signals are shown in Table 36
Table 36 - Input values vs. External
chilled-water setpoint
3.7 7.2
-10
4.8 9.2
-5
5.9 11.3
0
7.1 13.3
5
8.2 15.4
10
Isolated 4-20 mA current source
input
Set dipswitch SW1-1 of the option
module A9 to "ON."
Connect the current source terminals
4 (+) and 5 (-).
CWS is now based on the following
equation:
Setpoint (°C) = (mA * 2.44) - 27.56
Resulting
chilled-water
setpoint (°C)
Voltage
(V (dc))
Current
(mA)
