Table of Contents
Advertisement
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.
Tracer® TU Service Tool is used to set the input signal type
from the factory default of 2-10 VDC to that of 4-20 mA.
Tracer® TU is also used to install or remove the External
Chilled Water Setpoint option as well as a means to enable
and disable ECWS.
External Demand Limit Setpoint (EDLS)
Option
Similar to the above, the controller also provides for an
optional External Demand Limit Setpoint (EDLS) that will
accept either a 2-10 Vdc (default) or a 4-20 mA signal. The
demand limit can also be set via the operator display or
through digital communication with Tracer® SC+ building
automation system or third party building automation
system. The arbitration of the various sources of demand
limit is described in the flow charts at the end of this
section. The EDLS may be changed from a remote location
by hooking up the analog input signal to the board 1A7, J2-
2 and 3. Refer to the following paragraph on Analog Input
Signal Wiring Details. The following equations apply for
EDLS if using default minimum 40% and maximum 120%.
Voltage Signal
As generated from external
source
As processed by the unit
controller
Current Signal
As generated from external
source
As processed by the unit
controller
If the EDLS 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 Demand
Limit Setpoint.
Tracer® TU must be used to set the input signal type from
the factory default of 2-10 Vdc to that of 4-20 mA current.
Tracer TU must be also be used to install or remove the
External Demand Limit Setpoint Option for field installation,
or can be used to enable or disable the feature (if installed).
EDLS and ECWS Analog Input Signal Wiring Details:
Both the ECWS and EDLS can be connected and setup as
either a 2-10 Vdc (factory default), 4-20 mA, or resistance
input (also a form of 4-20mA) as indicated below.
Depending on the type to be used, Tracer TU must be used
to configure the LLID and the controller for the proper input
type that is being used. This is accomplished by a setting
change on the Custom Tab of the Configuration View within
Tracer TU.
AC-SVX003A-EN
VDC=0.1 (%) -2.0
%=10*(VDC)+20
mA=0.2 (%) -4.0
%=5*(mA)+20
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
EDLS 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.
Figure 24. Wiring examples for EDLS and ECWS/
EHWS
EDLS and ECWS Analog Input Signal
Wiring
Both the ECWS and EDLS can be connected and setup as
either a 2–10 VDC (factory default), 4-20 mA, or resistance
input (also a form of 4–20mA) as indicated below.
Depending on the type to be used, the Tracer® TU Service
Tool must be used to configure the LLID and the main
processor for the proper input type that is being used. This
is accomplished by a setting change on the Custom Tab of
the Configuration View within Tracer® TU.
Important: For proper unit operation, BOTH the EDLS and
ECWS settings MUST be the same (2-10 VDC
or 4-20mA), even if only one input is to be
used.
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 EDLS uses terminals J2–2 and J2–3. ECWS uses
terminals J2–5 and J2–6. Both inputs are only compatible
with highside current sources.
Installation Electrical
71
Advertisement
Table of Contents
