Carrier Omnizone 50BVC Installation, Start-Up, Service And Controls Operation And Troubleshooting page 34

High Pressure Protection
If the HP1 or HP2 switches are open upon a Y1 or Y2 call, the
UPM will not energize the respective CC1 or CC2 outputs; the
corresponding compressor will remain off, the fault LED will
flash 1 time for the HP1 and 3 times for HP2, and the alarm con-
tact will remain off.
If a compressor is running in normal mode on a Y call (Y1 or Y2
or both) and the high pressure switch opens, the UPM will shut
down the compressor output and will keep it off until the switch
closes and the anti-short cycle has expired. The controller will
keep track of the number of times the switch opens; if, within a 1-
hour period, the switch opens the number of times set via the DIP
switch, the controller will shut down the compressor and perform
a hard lockout condition. Under this condition the alarm contact
will be energized.
The UPM allows the user to configure the counts that the HP will
be allowed to open within 1 hour before the UPM performs a hard
lockout on the compressor. The user can select either two or four
times by changing switch 4 on the DIP switch SW1 on the UPM
board.
Low Pressure Protection
If the LP1 or LP2 switches are open upon a Y1 or Y2 call (Y1 or
Y2 or both) the UPM will not energize the CC1 or CC2 outputs;
the corresponding compressor will remain off, the fault LED will
flash two times for the LP1 and 4 times for the LP2, and the alarm
contact will remain off.
If the compressor is running in normal mode on a Y call (Y1 or Y2
or both) and the low pressure switch opens, the UPM will keep the
compressor running for 2 minutes. If the condition remains after
Fig. 24 — Two-Stage Unit Protection Module
34
this period of time, the compressor will shut down and the UPM
will start a soft lockout. The UPM will flash 2 times for the LP1
and 4 times for the LP2 and the alarm contact will remain off.
If the switches close, the UPM will start the compressor after the
anti-short cycle has expired and UPM will energize the compres-
sor output.
IMPORTANT: To exit the hard lockout the controller must be
reset from the Y or R terminal by removing the power from the
selected terminal. The user can choose which will be the reset
point via the DIP switch SW1.
Ground
The UPM controller takes its ground reference from the unit chas-
sis which is connected to the controller via the C-GND spade ter-
minal.
DIP Switch Settings
The DIP switch is used to configure most of the available features
of the UPM as follows:
• Alarm mode, Constant or Pulse
• Reset mode, Y signal or R signal
• Lockout mode, 2 or 4 strikes
• Test mode, Normal or Test operation
The settings shown in Fig. 25 are factory default. The unit wiring
diagram is the ultimate guide for factory DIP switch default
settings.