JOHNSON CONTROLS
129
SECTION 7 – UNIT CONTROLS
FORM 150.72-ICOM6
ISSUE DATE: 12/29/2017
7
Depending on the option, the trip voltage for a
specific system or unit high current trip can be
programmed. It also calibrates the current read-
out under the OPER DATA key. The approximate
programmed value is calculated using the following
formulas.
System Trip Volts
For individual system high current trip programming
on chillers:
• Add the sum of the compressor and fan RLA’s in
the system
• Multiply the sum by 1.25
• Divide by 225A
• The resulting voltage is the value that should be
programmed
For example, if fan and compressor RLA’s total 100A:
5V x 100A
x 1.25 =
625VA
= 2.8V
225A 225A
The programmed value will be 2.8V. A similar calcula-
tion and programming will be necessary for the other
system in a 2-system chiller.
Unit Trip Volts
For total chiller high current trip programming on
460VAC chillers:
• Add the sum of all the compressors and fan RLA’s
in the chiller
• Multiply the sum by 1.25
• Divide by 225A
• The resulting voltage is the value that should be
programmed
For example, if fan and compressor RLA’s total 180A:
5V x 180A
x 1.25 =
1125VA
= 5.0V
225A 225A
The programmed value will be 5.0V.
R E M O T E U N I T I D
P R O G R A M M E D = X
When communications is required with a BAS or Op-
tiView Panel, individual unit IDs are necessary for
communications with specific chillers on a single RS-
485 line. ID 0 - 7 is selectable.
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