Trane RTAC 150 Series

42 RTAC-SVX002A-EN
Installation Electrical
permit the ice building mode to be
reentered until the unit has been
switched out of ice building mode (open
5K18 contacts) and then switched back
into ice building mode (close 5K18
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 5K18 to the proper
terminals of 1U7. Refer to the eld
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 CH530 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 denes the
set point. This input is primarily used
with generic BAS (building automation
systems). The chilled water setpoint
set via the DynaView or through digital
communication with Tracer (Comm3).
The arbitration of the various chilled
water setpoint sources is described in
the ow charts at the end of the section.
The chilled water setpoint may be
changed from a remote location by
sending either a 2-10 VDC or 4-20
mA signal to the 1U6, 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:
Voltage Signal Current Signal
As generated from VDC=0.1455*(ECWS)+0.5454 mA=0.2909(ECWS)+1.0909
external source
As processed by CH530 ECWS=6.875*(VDC)-3.75 ECWS=3.4375(mA)-3.75
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
(DynaView) Chilled Water Setpoint.
TechView Service Tool is used to set
the input signal type from the factory
default of 2-10 VDC to that of 4-20
mA. TechView is also used to install
or remove the External Chilled Water
Setpoint option as well as a means to
enable and disable ECWS.
External Current Limit Setpoint
(ECLS) Option
Similar to the above, the CH530 also
provides for an optional External
Current
Limit Setpoint that will accept either a
2-10 VDC (default) or a 4-20 mA signal.
The Current Limit Setting can also be
set via the DynaView or through digital
communication with Tracer (Comm 3).
The arbitration of the various sources
of current limit is described in the ow
charts at the end of this section. The
External Current Limit Setpoint may
be changed from a remote location
by hooking up the analog input signal
to the 1 U6 LLID terminals 2 and 3.
Refer to the following paragraph on
Analog Input Signal Wiring Details. The
following equations apply for ECLS:
Voltage Signal Current Signal
As generated from VDC+0.133*(%)-6.0 mA=0.266*(%)-12.0
external source
As processed by UCM %=7.5*(VDC)+45.0 %=3.75*(mA)+45.0