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SECTION 15 - PROXIMITY PROBE
On chillers equipped with Probe 025-30961-000 and
Flash memory card version C.MLM.01.02 (and ear-
lier), if the Drain Line Temperature increases to greater
than or equal to 250.0°F (121.1°C), a safety shutdown
is performed and THRUST BEARING - HIGH OIL
TEMPERATURE is displayed. If the Temperature sig-
nal output of the Probe decreases to 0 VDC, it is indica-
tive of an open circuit or a broken wire to the Probe and
a safety shutdown is initiated and "THRUST BEAR-
ING - OIL TEMPERATURE SENSOR" is displayed.
When any of the above Thrust Bearing related safety
shutdowns occur, the chiller cannot be restarted until a
special reset procedure is performed by a Service tech-
nician. Some of these shutdowns also require a thrust
bearing inspection. The reset procedure and bearing
inspection criteria is listed in SECTION 33 - SYSTEM
CALIBRATION, SERVICE SETPOINTS, AND RESET
PROCEDURES of this manual.
The Proximity Position output of the Probe is measured
at the microboard at J8-15 and is calculated as follows:
V = D - 8.14
20.86
D = 20.86 X V + 8.14
Where: V = VDC
D = Distance in Mils
The High Speed Drain Temperature output of Probe
025-30961-000 is measured at the microboard at J8-1
and is calculated as follows:
V = T - 18.75
62.5
T = 62.5 X V + 18.75
Where: V = VDC
T = Temperature in degrees F
The chiller could be equipped with one of several dif-
ferent Probes. The Probe differences vary with the
vintage. The differences are listed in Table 12 on page
159. For service replacement, refer to part number
listed in Renewal Parts – OptiView Control Center
(Form 160.54-RP1) or the unit renewal parts manual.
158
For Microboard 031-01730-000, Microboard program
jumpers JP41 and JP42 must be positioned appropri-
ately to provide proper operation of actual probe in-
stalled. Refer to Microboard Program Jumpers.
The Probe cannot accurately measure the gap distance
if its supply voltage, +24 VDC, decreases to less than
19.0 VDC. To prevent an invalid Proximity gap safety
shutdown due to a Utility Power sag, the microboard
monitors the Probe's 24 VDC power source at J9-12 on
the microboard. If it decreases to less than 19.0 VDC,
a cycling shutdown is performed and Proximity probe
- LOW SUPPLY VOLTAGE is displayed. The chiller
will automatically restart when the voltage increases
above +19.7 VDC.
JCI COMPANY CONFIDENTIAL
ISSUE DATE: 10/25/2019
IMPORTANT! Probes 025-35900-000,
025-35900-001 and 025-40496-000 do not
sense the High Speed Drain Temperature.
The value returned from the Probe for
this temperature will be 0 VDC. If the
software reads this value, the 0 VDC value
will cause the chiller to be locked out on
the safety "THRUST BEARING – OIL
TEMPERATURE SENSOR" (complete
explanation of this message is in OptiView
Control Panel – Operation (Form 160.54-
O1). Therefore, the software used must be
of a later vintage that does not read this
parameter. For Microboards 031-01730-
000, Software versions C.MLM.01.03
(and later) do not read this parameter
and are required for these probes. If the
software does not meet this requirement,
a new Flash Card (031-01797) must be
ordered at the same time as the probe.
For Microboards 031-02430-000/001, all
versions of software do not read this input
and therefore meet this requirement.
JOHNSON CONTROLS
FORM 160.54-M1
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