JOHNSON CONTROLS
120
FORM 150.27-NM1
ISSUE DATE: 09/30/2015
SECTION 7 – UNIT CONTROLS
N U
M
B
E
R
O
F F A
N
S
P E
R S Y S T E
M = X
Does not apply to a YCRL chiller.
S Y S X T R I P V O L T S
= X . X V O L T S
U N I T T R I P V O L T S
= X . X V O L T S
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.
T O T A L N U M B E R O F
C O M P R E S S O R S = 6
The TOTAL NUMBER OF COMPRESSORS is the
total quantity of compressors in the chiller, and de-
termines the stages of cooling available. Dual system
units may have 4 or 6 compressors.
This MUST be programmed correctly to
assure proper chiller operation.
A single system chiller MUST have a
jumper between terminals J9-7 and +24V
on the I/O board. This connection can
be made between terminals 13 and 17 on
terminal block CTB1. If the jumper is not
installed, the unit will act as a 2-system
chiller. The jumper is only checked by
the microprocessor at unit power-up. If
the jumper is removed, power must be
removed and re-applied to register the
change in memory.
This MUST be programmed correctly to
assure proper chiller operation.
