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r
2-14
efrIgeratIon
Safety controls are installed on Freedom
condensing units to protect the compressor
from various errors or adverse conditions:
•
High pressure safety control
•
Low pressure safety control
•
Compressor discharge temperature sensor
Air cooled condensing units with Electronic
Unit Controller:
On condensing units that are equipped with
the Emerson Electronic Unit Controller, the
pressure controls and discharge line alarm
are incorporated into the controller on the
condensing unit.
The high pressure cut-out is a non-
adjustable pressure switch with a cut-out
of 440 psig. The low pressure control and
compressor discharge temperature setpoint
are programmed into the electronic unit
controller on the condensing unit. The
compressor discharge temperature is set to
cut out at 225°F. The low pressure control is
set to cut out at 15 psig, and cut in at 25 psig.
For low temp units, the control is set to cut
out at 5 psig and cut in at 15 psig.
Parameter
P4P
AP2
AU2
AH2
Ad2
dA2
AC2
tbA
i1F
i2P
i2F
did
nPS
P/N 0520677_W
/e
/C
leCtrICal
ontroller
ELECTRONIC CONTROLLER
Description
Fourth probe presence
Probe selection for condener temperature alarm
Condenser high temperature alarm
Differ for condenser temperature alarm recovery
Condenser temperature alarm delay
Delay of condenser temperature alarm at startup
Compressor off for condenser high temperature alarm
Alarm relay switch off by pushing a key
Digital input 1 configuration
Digital input 2 polarity
Digital input 2 configuration
Digital input 2 alarm delay
Number of activations of pressure switch
U.S. & Canada 1-800-922-1919 • Mexico 1-800-890-2900 • WWW.HUSSMANN.COM
Air cooled condensing units without Electronic
Unit Controller:
On Freedom cases that have condensing
units that are not equipped with the Emerson
Electronic Unit Controller, including water
cooled units, the high and low pressure safety
controls are connected to terminals 18 and
19 of the XR75 case controller. Air cooled
unit have a discharge line sensor, which is
connected to terminals 21 and 23. The case
controller parameters are set at the factory
to incorporate the controls. The pressure
controls are not adjustable. The discharge
safety is set in the case controller to cut out
at 230°F.
These controls must be connected after
installation of the condensing unit. Harnesses
are provided and marked to show the
connections (see wiring diagram on next page).
The parameters in the Dixell XR75 are set up
in the factory to enable the pressure control
functionality. The parameters affecting this
control are shown in the diagram below.
Value
yes
P4
220
45
15
0
yes
yes
dor
OP
PAL
30
3
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