York YLAA0041 Installation Operation & Maintenance page 157

Form 150.72-ICOM6
Issue date: 12/19/2023
The Fan Control On Pressure is the programmed pres-
sure value that is used to stage the condenser fans on, in
relation to discharge pressure. See Standard condenser
fan control on page 179 in Section 7: Unit controls
and Table 24 on page 181 and Table 25 on page 182.
F A N D I F F E R E N T I A L
P R E S S U R E =
The Fan Differential Off Pressure is the programmed
differential pressure value that is used to stage the con-
denser fans OFF, in relation to discharge pressure. See
Standard condenser fan control on page 179 in Sec-
tion 8: Unit operation and Table 24 on page 181 and
Table 25 on page 182.
T O T A L N U M B E R
C O M P R E S S O R S
The TOTAL NUMBER OF COMPRESSORS is the
total quantity of compressors in the chiller, and deter-
mines the stages of cooling available. Note in Table 18
on page 158, the chiller may have single or dual sys-
tems. Single system units can have 2 or 3 compressors,
while dual system units may have 4 or 6 compressors.
This MUST be programmed correctly to
ensure proper chiller operation.
N U M B E R O F
P E R S Y S T E M
The Number of Fans Per System must be programmed
as needed to match the number of fans on each system.
S Y S X T R I P
U N I T T R I P
= X . X
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.
Johnson Controls
O F F
X X X P S I G
O F
= 6
F A N S
= X
V O L T S
= X . X V O L T S
V O L T S
V O L T S
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 225 A
• The resulting voltage is the value that should be
programmed
For example, if fan and compressor RLA's total 100 A:
5 V x 100 A
x 1.25 =
225 A
The programmed value will be 2.8 V. 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 460
VAC chillers:
• Add the sum of all the compressors and fan RLA's
in the chiller
• Multiply the sum by 1.25
• Divide by 225 A
• The resulting voltage is the value that should be
programmed
For example, if fan and compressor RLA's total 180 A:
5 V x 180 A
x 1.25 =
225 A
The programmed value will be 5.0 V.
R E M O T E U N I T
P R O G R A M M E D
When communications is required with a BAS or
OptiView Panel, individual unit IDs are necessary for
communications with specific chillers on a single RS-
485 line. ID 0 - 7 is selectable.
A N T I - V A C S U C T
C U T O U T = XXXX PSIG
A N T I - V A C D E L A Y
= XX S E C
Section 7: Unit controls
625 VA
= 2.8 V
225 A
1125 VA
= 5.0 V
225 A
I D
= X
P R E S S
T I M E
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