158
FORM 160.54-M1
ISSUE DATE: 10/25/2019
SECTION 15 - PROXIMITY PROBE
JCI COMPANY CONFIDENTIAL
JOHNSON CONTROLS
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
CALIBRATION, SERVICE SETPOINTS, AND RESET
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
. For service replacement, refer to part number
listed in
Renewal Parts – OptiView Control Center
(Form 160.54-RP1)
or the unit renewal parts manual.
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.
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.
