York YLAA0285SE Manual page 142

SECTION 7 – UNIT CONTROLS
The internal motor protector opens at 185 °F – 248 °F
(85 °C – 120 °C) and auto resets. The mechanical HP
switch opens at 585 PSIG +/- 10 PSIG (27.92 barg +/- .69
barg) and closes at 330 PSIG +/- 25 PSIG (22.75 barg
+/- 1.72 barg).
The compressor is also equipped with a discharge
temperature sensor for the purpose of sensing internal
scroll temperature. This sensor protects the scrolls
from overheating due to inadequate cooling that may
occur when refrigerant charge is low or superheat is
too high.
When the sensor indicates a high temperature, it opens
the motor protector circuit in the compressor causing
the compressor to shut down.
During the first two faults an MP/HP INHIBIT message
will be displayed and the system will not be locked out.
Only after the third fault in 90 minutes will the MP/
HPCO FAULT message be displayed.
Whenever the motor protector or discharge sensor
shuts down a compressor and the system, the internal
compressor contacts will open for a period of 30 minutes
to assure that the motor or scroll temperatures have
time to dissipate the heat and cool down. The MP/
HP INHIBIT message will be displayed while these
contacts are open or when the HPCO is open. While
this message is displayed, the compressors will not be
permitted to start.
After 30 minutes, the contacts will close and the system
will be permitted to restart. The microprocessor board
will not try to restart the compressors in a system that
shuts down on this safety for a period of 30 minutes to
allow the internal compressor to time out.
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During the 30 minute timeout, the MP/HPCO INHIB
message will be displayed. The MP/HPCO fault will
only be displayed after 3 shutdowns in 90 minutes,
indicating the system is locked out and will not
restart.
S Y S 1 H I G H
S Y S 2 H I G H
When the System Current Feedback option is installed
and selected (Option 11 under OPTIONS Key Current
Feedback), this safety will operate as follows. If the
actual feedback voltage of the system, proportional to
currents, exceeds the programmed trip voltage for 5
seconds, the system will shutdown.
This safety will shut down a system if either suction
temperature or suction pressure sensors read out of
range high or low. This condition must be present for 3
seconds to cause a system shutdown. The safety locks
out a system after the first fault and will not allow
automatic restarting.
FORM 150.72-NM3 (1020)
ISSUE DATE 10/05/2020
M T R C U R R
M T R C U R R
JOHNSON CONTROLS