Trane RTWD Installation Operation & Maintenance page 65

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 fl 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 1A7, J2-4 and 5. Refer to the following
paragraph on Analog Input Signal Wiring Details. The
following equations apply for ECLS:
Voltage signal
As generated
from external VDC + 0.133* (%)-6.0
source
As processed
%=7.5*(VDC)+ 45.0
by CH530
If the ECLS input develops an open or short, the LLID
will report either a very high or very low value back to
the man processor. This will generate an informational
diagnostic and the unit will default to using the Front
Panel (DynaView) Current Limit Setpoint. The TechView
Service Tool must be used to set the input signal type
from the factory default of 2-10 VDC to that of 4-20 mA
current. TechView must be also be used to install or
remove the External Current Limit Setpoint Option for
fi eld installation, or can be used to enable or disable the
feature (if installed).
ECLS and ECWS Analog Input Signal Wiring Details:
Both the ECWS and ECLS can be connected and setup
as either a 2-10 VDC (factory default), 4-20 mA, or
resistance input (also a form of 4-2OmA) as indicated
below. Depending on the type to be used, the TechView
Service Tool must be used to confi gure the LLID and the
MP for the proper input type that is being used. This is
accomplished by a setting change on the Custom Tab of
the Confi guration View within TechView.
RLC-SVX14H-GB
The J2-3 and J2-6 terminal is chassis grounded and
terminal J2-1 and J2-4 can be used to source 12 VDC.
The ECLS uses terminals J2-2 and J2-3. ECWS uses
terminals J2-5 and J2-6. Both inputs are only compatible
with high-side current sources.
Chilled Water Reset (CWR)
CH530 resets the chilled water temperature set point
based on either return water temperature, or outdoor air
temperature. Return Reset is standard, Outdoor Reset is
optional.
The following shall be selectable:
• One of three Reset Types: None, Return Water
• Reset Ratio Set Points.
• For outdoor air temperature reset there shall be both
• Start Reset Set Points.
• Maximum Reset Set Points.
Figure 12 - Wiring Examples for ECLS and ECWS
Current signal
mA = 0.266*(%)-12.0
%=3.75*(mA)+ 45.0
Installation – Electrical
Temperature Reset, Outdoor Air Temperature Reset,
or Constant Return Water Temperature Reset.
positive and negative reset ratio's.
Potentiometr
Resistor
Dual
Analog
I/O LLID
Dual
Analog
I/O LLID
Dual
Analog
I/O LLID
Dual
Analog
I/O LLID
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