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3.3
SYSTEM # DATA KEYS
Pressing one of the System # Data keys a number of
times scrolls through displays of differential oil pressure
(OIL), suction pressure (SP) and discharge pressure
(DP), oil temperature, suction temperature (ST), dis-
charge temperature (DT), saturated suction temperature,
suction superheat, saturated discharge temperature,
discharge superheat and compressor slide valve position.
Examples of these displays are as follows where # is the
appropriate system number:
S Y S
#
O I L =
S P =
6 4
D P =
S Y S
#
O I L
S T =
3 1 . 0
D T =
S #
S A T
S U C T
S U C T
S H E A T
S #
S A T
D S C H = 1 3 0 . 0 ° F
D S C H
S H E A T
S Y S
#
S
V
S Y S
#
C O O L E R
R E F R I G
T E M P =
The Cooler Inlet Temp. display will
only appear if the chiller is selected
for R407C.
Temperatures and pressures are either measured directly
by transducers and temperature sensors, or computed
from these measurements as follows:
Saturated discharge and suction temperatures are com-
puted by converting measured pressure to temperature.
Slide Valve Position is computed based on the number
of loading steps that the micro has sent to the slide
valve solenoid in the form of a current signal. To the
microprocessor, STEP 0 = fully unloaded and STEP 75
= fully loaded.
JOHNSON CONTROLS
1 7 6
P S I G
1 9 5
P S I G
=
1 5 7 . 4 ° F
1 2 3 . 2 ° F
=
3 2 . 9 ° F
=
1 5 . 0 ° F
=
5 4 . 3 ° F
S T E P
=
3
I N L E T
2 8 . 2 ° F
Slide valve position is APPROXI‑
MATE and should be used for ref‑
erence only. Under actual conditions
the compressor may be fully loaded
between step 60 ‑ 75 and fully unloaded
between step 0 ‑ 40.
Superheats are the difference between the respective
saturated temperature (converted from pressure) and the
actual. Display Limits for the System Pressures and
Temperatures displays are as follows:
MIN. LIMIT
Oil Pressure
208 PSID (14 Bar) 0 PSID (0 Bar)
Suction Pressure
0 PSIG (0 Bar) 199 PSIG (14 Bar)
Discharge Pressure
0 PSIG (0 Bar) 399 PSIG (28 Bar)
Suction Temp.
*9.0 °F (-13°C)
Discharge Temp.
40.3 °F (5°C)
Oil Temp.
40.3 °F (5°C)
Sat. Discharge Temp.
-41.0 °F (-41°C)
Sat. Suction Temp.
-41.0 °F (-41°C)
Slide Valve Position
0% (0%)
Suction Superheat
*-81.5 °F (-63.1°C) 60.9 °F (16°C)
Discharge Superheat
22.5 °F (-5.3°C) 216.0 °F (102.2°C)
Minimum and maximum values may
change as software (EPROM) revi‑
sions are made.
*Below 9.0°F (13°C), the Suction
Temp. display will disappear. This will
in turn cause the Superheat display to
disappear.
3.4
AMBIENT TEMP KEY
When the Ambient Temperature key is pressed, ambient
air temperature, as measured surrounding the chiller, is
displayed.
A M B I E N T
=
7 1 . 9
Display Limits: Minimum
Maximum 137.9°F
FORM 201.18-NM7
MAX. LIMIT
84.2 °F (29°C)
302.6 °F (150°C)
240.0 °F (116°C)
140.5 °F (60°C)
101.3 °F (39°C)
100% (100%)
A I R
T E M P
° F
-4.6°F (-20.3°C)
(58.8°C)
143
8
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