Module Power and Miscellaneous I/O
84 RTHC-SVD01B-EN
Ext Chilled Wtr Setpt: (Installed, Not Installed)
Ext Current Limit Setpt: (Installed, Not Installed)
External Analog Inputs: (4-20 mA, 2-10 VDC)
Note:For proper operation, the 4-20 mA/2-10 VDC inputs are required
to be used with a current or voltage source that:
1. Is isolated (floats) with respect to ground, or
2. Has its negative terminal tied to chassis ground.
If the intended source does not meet the above requirement, an isola-
tion module must be used.
The 4-20 mA/2-10 VDC inputs may be tested in the following way:
1. Enable External Chilled Water Setpoint and/or External Current
Limit Setpoint in the Operator Settings Menu. Advance display to
Active Chilled Water Setpoint or Active Current Limit Setpoint to
observe the respective setpoint in the Chiller Report.
2. With all wiring in place, apply an external voltage or current to the
External Chilled Water Setpoint inputs (J9-4,5) or the External
Current Limit Setpoint (J7-11, 12). The voltage measured at the
terminals and the resulting setpoint, as read on the CLD, should
agree with the Table 9-10 for Chilled Water Setpoint inputs and
Table 9-11 for Current Limit Setpoints inputs. Be sure to wait long
enough when reading the display as the values are filtered.
NOTE: A 9 volt battery works well when trying to diagnose a 2-10 VDC
signal problem. Disconnect the signal and wire in the battery to simu-
late a 9 VDC signal. This is polarity sensitive. For Current Limit J7-11 is
battery negative and J7-12 is battery positive. For Chilled Water Set-
point J9-4 is battery negative and J9-5 is battery positive,
1. Disconnect all wiring to these inputs. The setpoints should
change back to the chiller's Front Panel settings
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