JOHNSON CONTROLS
170
FORM 150.67-NM2
ISSUE DATE: 01/31/2019
SECTION 8 – UNIT OPERATION
TB3
TB1
TB2
TO PANEL 7M TO FAN #1 (EXISTING HARNESS)
TO MICROBOARD (P4)
151
150
152
150A
151A
152A
WHT
BLK
TB3
TB1
TB2
TB3
TB1
TB2
TO PANEL 7M TO FAN #1 (EXISTING HARNESS)
TO MICROBOARD (P4)
151
150
152
150A
151A
152A
WHT
BLK
LD11302a
FIGURE 53 - INVERTER WIRING
TABLE 27 - YCAL033 VFD LOW AMBIENT OPTION – CONDENSER FAN CONTROL OPERATION
FAN STAGE ON OFF
CONTACTOR
MICRO
BOARD
FAN #
SYS 1 SYS 1 SYS 1
1:
VFD Control
(1 fan
Variable Speed)
Fan Speed
Is A Function Of
Discharge Pressure.
When The Liquid Line
Solenoid Is Energized.
Speed Increases With
Pressure
FAN Will Turn Off or Turn
Very Slowly When Pres-
sure Drops Below 260
PSIG.
7M TB7-3 1
2:
1 Fan VFD Con-
trol
2nd Fan Full
Speed Under
Contactor Control
425 PSIG,
Both Fans
Will Be Running Full
Speed
Discharge Pressure
< 260 PSIG (Pressure Is
< Fan Control ON Pres-
sure of
425 PSIG Minus Fan
Differential
Pressure of 125 PSIG =
300 PSIG)
7M
&
8M
TB7-3
&
TB7-10
3
tures, assuring superheat and oil control is not compro-
mised. When the chiller and VFD fan control points are
programmed properly, the fans will operate as outlined
in Table 27 on page 170.
Programming as suggested assures the chiller control
points for the second fan in the fan staging sequence
and the inverter control points are matched for opti-
mum control of the fans at reduced ambient tempera-
FIGURE 52 - INVERTER POWER WIRING SCHEMATIC
LD11301a
150A L1 T1 150
151A L2 T2 151
152A L3 T3 152
CONDENSER
FAN NO. 1
SPEED
CONTR.
7M
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