Installation and Maintenance Manual

Installation - Electrical
110 RLC-SVX09H-EN
External Chilled or Hot Water Setpoint
(ECWS/EHWS) Option
The CH530 provides inputs that accept either 4-20 mA or 2-
10 VDC signals to set the external water setpoint (EWS).
• When the unit is in cooling mode, the EWS will
correspond to the chilled water setpoint (ECWS).
• When the unit is in heating mode, the EWS will
correspond to the hot water setpoint (EHWS).
This is not a reset function.The input defines the set point.
This input is primarily used with generic BAS (building
automation systems).The water setpoint set via the
DynaView or through digital communication withTracer
(Comm3). See Figure 45, p. 111 for wiring diagrams.
The chilled water setpoint may be changed from a remote
location by sending either a 2-10VDC or 4-20 mA signal to
the 1A7, J2-5 and 6. The widest range of temperatures
available for the 2-10 VDC and 4-20 mA signals each
correspond to:
• ECWS of 10 to 65°F (-12.22 to 18.4°C)
• EHWS of 68 to 140°F (20 - 60°C).
The external chilled water setpoint (ECWS) and external
hot water setpoint (EHWS) minimum and maximum
values are configurable. See Table 93 for default values.
The equations in Table 94 apply if using default minimum
and maximum values, as shown in above.
If minimum and maximum values have been changed
from default values in Table 93, use the following
equations:
If the ECWS/EHWS 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/Hot Water Setpoint.
TechView ServiceTool 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
ChilledWater 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 2-10VDC (default) or a 4-20 mA signal.The Current
Limit Setting can also be set via the DynaView or through
digital communication withTracer (Comm 3).The
arbitration of the various sources of current limit is
described in the flow 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 board 1A7, J2-2 and 3. Refer to the following paragraph
on Analog Input Signal Wiring Details.The following
equations apply for ECLS:
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.
TheTechView 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.TechView must be also be used to install
or remove the External Current Limit Setpoint Option for
field 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 4-20mA) as indicated below.
Table 93. Default minimum and maximum values
Default Temperature
External Water Setpoint Minimum Maximum
Chilled (ECWS) 34°F (1.1°C) 65°F (18.4°C)
Hot (EHWS) 86
°F (30°C) 122°F (50°C)
Table 94. EWS equations -
default minimum and maximum values
(a)
(a) Temperatures are in units of °F.
Chilled Water
Setpoint Voltage Signal Current Signal
As generated
from external
source
VDC=
0.1455*(ECWS)
+0.5454
mA=
0.2909*(ECWS)
+1.0909
As processed by
CH530
ECWS=
6.875*(VDC)-3.75
ECWS=
3.4375*(mA)-3.75
Hot Water
Setpoint Voltage Signal Current Signal
As generated
from external
source
VDC=
0.2222*(EHWS)
-17.1092
mA=
0.4444*(EHWS)
-34.2184
As processed by
CH530
EHWS=
4.5*(VDC)+77
EHWS=
2.25*(mA)+77
Table 95. EWS equations -
any minimum and maximum values
(a)
(a) Temperatures are in units of °F.
For Voltage
Input Signal
EWS = Min + (Max - Min)*(VDC - 2)/8
For Current
Input Signal
EWS = Min + (Max - Min)*(mA - 4)/16
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