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SECTION 2 - SYSTEM ARCHITECTURE
FORM 160.54-M1
ISSUE DATE: 10/25/2019
JOHNSON CONTROLS
JCI COMPANY CONFIDENTIAL
2
A front panel-mounted keypad allows operator and ser-
vice technician user interface. Membrane keys are used
to display chiller and system parameters, enter set-
points and perform chiller and OptiView Control Cen-
ter diagnostics. It also contains a START-RUN-STOP/
RESET switch that is used to locally start and stop the
chiller and perform manual reset functions.
A front panel mounted liquid crystal display allows
graphic animated display of the chiller, chiller subsys-
tems and system parameters. The chiller and working
components of the chiller are displayed, along with
chiller operating pressures and temperatures. The key-
pad is used to select displays showing increasing levels
of detail of chiller working components.
A self-contained power supply supplies the necessary
DC voltages for all the components within the OptiV-
iew Control Center.
Chillers equipped with
P
compressors and Style F and
later chillers have a different Condenser High Pressure
Safety Cutout Switch (HPCO) than supplied on other
applications. This switch is mounted on the condens-
er shell but has a different wiring interface to the I/O
Board and Motor Controller circuit. For more informa-
tion see
of this manual.
Also, P compressor applications and Style F and later
chillers with G, Q and H5-8 compressors are equipped
with a High Speed Thrust Bearing Limit Switch instead
of the proximity probe supplied on other compressors.
This device detects abnormal bearing position through
probe contact instead of distance measurement as per-
formed with the Proximity probe.
Style C (and earlier) chillers are equipped with fixed
speed oil pumps. Style D (and later) chillers are
equipped with variable speed oil pumps.
Style F (and later) chillers require flash memory card
version C.MLM.01.07.xxx and later and are supplied
with factory-mounted flow sensors on the evaporator
and condenser. These are electronic thermal-type sen-
sors.
The operating principle of the sensor is thermal con-
ductivity. It uses the cooling effect of a flowing liquid
to sense flow. The temperature of the heated sensor tip
is sensed by a thermistor located in the tip. A second
thermistor, located higher in the tip in a non-heated
area, is only affected by changes in liquid tempera-
ture. The temperatures sensed by the thermistors are
compared. Flowing liquid carries heat away from the
heated sensor tip, lowering its temperature. The lower
temperature differential between the two thermistors
indicates the liquid is flowing. A higher differential in-
dicates no flow.
These sensors are interfaced to microboard analog
inputs. See the
for a detailed explanation of this flow sen-
sor and interface.
If equipped with flash memory card version
C.MLM.01.07.xxx (and later), the chiller style/com-
pressor combination must be entered using the Chiller
Style/Compressor setpoint (See
TONNAGE CHILLER (LTC) I/O BOARD 031-02895-
). Once the applicable chiller style/compres-
sor combination is entered, the program automatically
bundles the functionality and chiller control per the
entered chiller style/compressor requirements. The
various chiller style/compressor combinations are
equipped differently and have different control re-
quirements. The variables include:
• High Speed Thrust Bearing proximity sensing –
Proximity probe or Limit Switch.
• Flow Sensor – Paddle type or factory mounted
Thermal type. The paddle type applies 115 VAC
to the I/O Board Digital inputs TB4-12 (evapora-
tor) and TB4-11 (condenser) (See
). The factory mounted thermal type
available with Style F (and later) chillers, applies
+5 VDC to the microboard Analog Inputs at J7-
14 (evaporator) and J7-16 (condenser). For more
information, see
.
Flash memory card version C.MLM.01.07.xxx
and C.MLM.01.07A.xxx automatically selects the
flow sensor input, either digital or analog per the
chiller style/compressor setpoint selection.
