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34
JOHNSON CONTROLS
FORM 150.68-ICOM1
ISSUE DATE: 10/15/2020
There are two programmable suction
pressure cut-out settings one for cooling
mode the other for heating/ defrost modes.
In the Cooling mode, the actual suction pressure cut-out
cooling is the programmed suction pressure cut-out
cooling. In the heating / defrost modes the suction
pressure cut-out heating programmed value is used as a
base line and is modified based on discharge pressure.
At a discharge pressure of 595 psig and above the actual
suction pressure cut-out equals the programmed suction
pressure cut-out heating. As the discharge pressure
fall below 595 psig to a minimum of 305 psig the
programmed suction pressure cut-out heating is lowered
lineally by a maximum of 65.25 psig. Below a discharge
pressure of 305 psig the actual suction pressure cut-out
is equal to the programmed suction pressure cut-out
heating minus 65.25 psig. The minimum actual suction
pressure cut-out is 29 psig. The actual suction cut-out
pressure can be found under the OPER DATA key.
SYS 1 ACTUAL SUCTION
CUTOUT = XXXX PSIG
At system start, the cut-out is set to 50% of the actual
suction pressure cut-out value. During the next 3 minutes
the cut-out point is ramped up to the actual cut-out point.
If at any time during this 3 minutes the suction pressure
falls below the ramped cut-out point, the system will
stop. This cut-out is ignored for the first 30 seconds
of system run time to avoid nuisance shutdowns. The
ramped cut-out value = (run time + 180 X actual cut-out
value / 360).
After the first 3 minutes, if the suction pressure falls
below the actual cut-out setting, a transient protection
routine is activated. This sets the cut-out at 50% of the
actual value and ramps up the cut-out over the next 30
seconds. If at any time during this 30 seconds the suction
pressure falls below the ramped cut-out, the system will
stop. The transient cut-out value = ((100 - (1.66 X actual
41
19
21
23
25
27
29
31
33
35
37
39
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0
0.5
SUCTION PRESSURE CUT-OUT
PROGRAMMED SUCTION PRESSURE CUT-OUT HEATING
D
IS
C
H
A
R
G
E
P
R
E
S
S
U
R
E
-5.0
cut-out value / 100)). The transient timer counts down
from 30 seconds.
SYS X LOW SUPERHEAT
This safety will shut down a system when the suction
superheat <2.0°F for programmed low superheat fault
time.
SYS X MP/HPCO INHIB
SYS X MP/HPCO FAULT
The Motor Protector (-FMP) / Mechanical High
Pressure Cut-outs (-FHP) protect the compressor
from overheating, overcurrent or from experiencing
dangerously high discharge pressure.
This fault condition is present when 1-K1 (system 1)
or 2-K1 (system 2) relays de-energize due to the -FHP
cut-out, or the -FMP opening.
-FMP
The compressor electronic modules are connected to
the motor winding temperature sensors and an internal
discharge temperature sensor. The -FMP opens when
the discharge temperature is above 284°F or when the
winding temperature rises above the trip temperature.
The winding and discharge sensors are connected in
series and have a trip resistance of 4.5 kΩ ±20%, reset
is less than 2.75 kΩ. The compressor electronic module
has a 30 ±5 minute reset delay after the sensor reset
resistance is reached.
-FHP
Mechanical high pressure cut-outs are fitted to meet
code requirements.
The cut-out -FHP auto reset is set to 585 psig.
The SYS MP/HPCO INHIBIT message indicates
that if the shutdown was due to a motor protector,
that when the motor protector resets the system will
restart automatically. If the shut down was due to the
mechanical high pressure cut-out, then the discharge
pressure must fall to the reset pressure.
The SYS MP/HPCO FAULT message indicates that the
system has locked out and requires an electrical reset,
in the case of the mechanical high pressure cut-outs.
Summary of Contents for YLPA 0115SE
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