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8 | Electrical
Units for remote Thermostat applications are provided
with a Unit Protection Module (UPM) that controls the
compressor operation and monitors the safety controls
that protect the unit.
Safety controls include the following:
•
High pressure switch located in the refrigerant
discharge line and wired across the HPC terminals
on the UPM
•
Low pressure switch located in the unit refrigerant
suction line and wired across terminals LPC1 and
LPC2 on the UPM.
UPM Board Dry Contacts are Normally Open (NO)
•
Water side freeze protection sensor, mounted close
to condensing water coil, monitors refrigerant
temperature between condensing water coil and
thermal expansion valve. If temperature drops
below or remains at freeze limit trip for 30 seconds,
the controller will shut down the compressor and
enter into a soft lockout condition. The default
freeze limit trip is 26°F, however this can be
changed to 15°F by cutting the R30 resistor located
above the UPM board settings. (See Figure # 3))
•
The condensate overflow protection sensor is
located in the drain pan of the unit and connected to
the 'COND' terminal on the UPM board. (Figure #3)
UPM Board Factory Default Settings
TEMP
LOCKOUT
RESET
ALARM
TEST
HOT/DRY ALARM
UPM DIP SWITCH DEFAULT POSITION
lockout
reset
alarm
test
The UPM Board includes the following features:
•
ANTI-SHORT CYCLE TIMER: 5 minute delay on
break timer to prevent compressor short cycling.
8733942456 (2016/04)
26°F
2
Y
PULSE
NO
NO
4
2
R
Y
Cont
pulse
yes
no
Subject to change without prior notice
•
RANDOM START: Each controller has an unique
random start delay ranging from 270 to 300 seconds
on initial power up to reduce the chance of multiple
unit simultaneously starting at the same time after
power up or after a power interruption, thus
avoiding creating large electrical spike.
•
LOW PRESSURE BYPASS TIMER: If the compressor
is running and the low pressure switch opens, the
controller will keep the compressor ON for 120
seconds. After 2 minutes if the low pressure switch
remains open, the controllers will shut down the
compressor and enter a soft lockout. The
compressor will not be energized until the low
pressure switch closes and the anti-short cycle time
delay expires. If the low pressure switch opens 2-4
times in 1 hour, the unit will enter a hard lockout. In
order to exit hard lockout, power to the unit would
need to be reset.
•
BROWNOUT/SURGE/POWER INTERRUPTION
PROTECTION: The brownout protection in the UPM
board will shut down the compressor if the
incoming power falls below 18 VAC. The compressor
will remain OFF until the voltage is above 18 VAC
and ANTI-SHORT CYCLE TIMER (300 seconds) times
out. The unit will not go into a hard lockout and does
not need to be reset.
•
MALFUNCTION OUTPUT: Alarm output is Normally
Open (NO) dry contact. If pulse is selected the alarm
output will be pulsed. The fault output will depend
on the dip switch setting for "ALARM". If it is set to
"CONST", a constant signal will be produced to
indicate a fault has occurred and the unit requires
inspection to determine the type of fault. If it is set
to "PULSE", a pulse signal is produced and a fault
code is detected by a remote device indicating the
fault. See L.E.D Fault Indication below for blink code
explanation. The remote device must have a
malfunction detection capability when the UPM
board is set to "PULSE".
If 24 VAC output is needed R must be wired to ALR-
COM terminal; 24 VAC will be available o the ALR-
OUT terminal when the unit is in the alarm condition.
•
DISPLAY OUTPUT:
output connected to the Unit Diagnostic Display
(UDD) and it pulses 24 VAC when the unit is in an
lockout alarm condition.
•
TEST DIP SWITCH:
to reduce all time delays settings to 10 seconds
during troubleshooting or verification of unit
operation.
NOTICE: Operation of unit in test mode can
lead to accelerated wear and premature
failure of components. The "TEST" switch
must be set back to "NO" after
troubleshooting/servicing.
CA Model
The Display output is a pulse
A test dip switch is provided
CA Model
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