Installation Electrical
RTAF-SVX001A-EN
29
mA each correspond to a 10 to 65°F (-12 to 18°C) external
chilled water setpoint.
The following relationships exist:
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.
TracerTU 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
ChilledWater Setpoint option as well as a means to enable
and disable ECWS.
External Demand Limit Setpoint (EDLS)
Option
Similar to the above, the UC800 also provides for an
optional External Demand Limit Setpoint that will accept
either a 2-10 VDC (default) or a 4-20 mA signal. The
Demand Limit Setting can also be set via the Tracer
AdaptiView™TD7 or through digital communication with
Tracer (Comm 3).The arbitration of the various sources of
demand limit is described in the flow charts at the end of
this section.The External Demand Limit Setpoint may be
changed from a remote location by hooking up the analog
input signal to the 1K24 LLID terminals 2 and 3. Refer to the
following paragraph on Analog Input Signal Wiring
Details. The following equations apply for EDLS:
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 (Tracer
AdaptiView™ TD7) Current Limit Setpoint.
TheTracer™TU ServiceTool must be used to set the input
signal type from the factory default of 2-10 VDC to that of
4-20 mA current.TracerTU must 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 4-2OmA) as indicated below.
Depending on the type to be used, the Tracer TU Service
Tool must be used to configure 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
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
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)
UC800 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
Temperature Reset, Outdoor AirTemperature Reset, or
Constant Return Water Temperature Reset.
•
Reset Ratio Set Points.
For outdoor air temperature reset there shall be both
positive and negative reset ratio's.
•
Start Reset Set Points.
•
Maximum Reset Set Points.
Voltage Signal
External Water Setpoint
< 1 VDC
Invalid
1 VDC to 2 VDC
min
2 VDC to 10 VDC
min + (max-min)* (Signal-2)/8
10 VDC to 11 VDC
max
> 11 VDC
Invalid
Current Signal
External Water Setpoint
< 2 mA
Invalid
2 mA to 4 mA
min
4 ma to 20 mA
min + (max-min)* (Signal-4)/16
20 mA to 22 mA
max
>22 mA
Invalid
Voltage Signal
Current Signal
As generated from
external source
VDC+0.133*(%)-6.0 mA=0.266*(%)-12.0
As processed by
UCM
%=7.5*(VDC)+45.0
%=3.75*(mA)+45.0
Figure 13. Wiring examples for EDLS and ECWS
J2-1 & 4 Dual
J2-2 & 5 Analog
J2-3 & 6 I/O LLID
J2-1 & 4 Dual
J2-2 & 5 Analog
J2-3 & 6 I/O LLID
J2-1 & 4 Dual
J2-2 & 5 Analog
J2-3 & 6 I/O LLID
Resister
2-10 VDC, 4-20mA
I = 20/(R + 200)
I
