JOHNSON CONTROLS
76
FORM 100.50-NOM6
ISSUE DATE: 8/07/2017
SECTION 5 – SEQUENCE OF OPERATION
COOLING COMPRESSOR LOCKOUT
This feature prevents operation of mechanical cooling
when the outdoor temperature is below this setpoint.
“OUTDOOR AIR TEMP COOLING LOCKOUT”
-
this parameter can be set using the COOLING SETUP
tab in the Simplicity PC software package.
This parameter should never be pro-
grammed less than 45.0° F
Sequence of Operation
On Cooling Compressor Lockout the following ap-
plies:
•
If the outdoor temperature is 1.0° F below the
“OUTDOOR AIR TEMP COOLING LOCKOUT”
the Simplicity Elite control will prevent compres-
sor operation.
•
When the outdoor temperature is 1.0° F above the
“OUTDOOR AIR TEMP COOLING LOCKOUT”
compressor operation will be permitted.
•
If the outdoor air temperature is less than the
economizer supply air temperature setpoint,
compressors will not operate regardless of the
“OUTDOOR AIR TEMP COOLING LOCKOUT”
setpoint.
LOW AMBIENT OPERATION
A condenser fan VFD can be installed on condenser
fan # l. When this is installed compressor system 1
(compressors 1A and 1B) can operate down to an out-
door temperature of 0.0° F. The VFD is located in an
enclosure on the right hand side of the condenser sec-
tion, to the right of the system 2 compressors.
To enable low ambient operation when a condenser fan
VFD is installed,
“LOWAMBIENT KITINSTALLED”
must be programmed by using Parameter 84 under the
PROGRAM key of the Simplicity Elite control board
or under the EQUIPMENT INSTALLATION tab in the
Simplicity PC software package.
Operation and Pressure Control Range
The VFD controls the speed of the fan based on a dis-
charge pressure setpoint and a differential range. When
discharge pressure reaches approximately 270 PSIG,
the VFD will start the fan if the Unit Controller is call-
ing for compressor / condenser fan operation. The bi-
nary outputs from the Unit Controller are as shown in
.
TABLE 27 -
BINARY OUTPUTS
CONDENSER
FAN
CONNECTOR
TERMINAL
#
WIRE
#
CONTACTOR
1A
P13
1
423
6M
As soon as the contactor is energized, the VFD will
be activated and will begin to control. As the pressure
rises over the next 80 PSIG (270 to 350 PSIG); the fan
speed will increase to full speed at approximately 350
PSIG.
The VFD control input signal originates from the dis-
charge pressure transducer for the compressor system
it is controlling. The transducer signal feeds the VFD.
The VFD controls the fan speed based on discharge
pressure.
Configuration (Jumpers and Potentiometers)
The inverter is configured at the factory. The jumpers
must be in the positions shown in
TABLE 28 -
VFD JUMPERS
JUMPER
60 HZ
50 HZ
J2
Remove
Remove
J3
Remove
Remove
J4
Remove
Remove
J5
Middle
Middle
J6
Middle
Middle
J7
IN
IN
J8
IN
IN
J9
IN for 60 Hz
Remove for 50 Hz
Potentiometer settings are also preset at the factory.
The potentiometers should be in the positions shown
in
. The potentiometers do not
have numerical settings and are set according to the
positions indicated. DO NOT change potentiometer
settings unless they do not match the positioning of
the potentiometers shown in
.
Modifying these settings may cause damage to the unit,
control problems, and/or poor operating efficiency.
TABLE 29 -
POTENTIOMETER SETTINGS
P1
P2
350 PSIG
80 PSIG
6 O’CLOCK
6 O’CLOCK
