FORM 160.54-M1(503)
89
YORK INTERNATIONAL
1
TB6
115VAC
I/O
BOARD
CONTROL CENTER
COMPRESSOR
TB3
81 1
2
SECTION 13A
HIGH SPEED THRUST BEARING LIMIT SWITCH
(REFER TO FIG. 49 - 50)
Chillers that are equipped with “P” compressors and
style F and later chillers with “G” or “H5-8” compressors
have a High Speed Thrust Bearing Limit Switch (025-
34535-000) instead of the Proximity Probe described in
Sec tion 13. This device detects abnormal bearing posi-
tion through probe contact instead of distance measure-
ment as performed with the Proximity Probe.
The High Speed Thrust Bearing Limit Switch is an
as sem bly consisting of a pressure switch attached to a
probe that protrudes into the compressor housing. When
the bearing position decreases to < the allowed position,
it comes into contact with the probe, causing the break-
away probe to detach, exposing the pressure switch to
the pressure inside the compressor. A set of normally
closed contacts inside the switch open when the switch
is ex posed to a pres sure of > 15 to 25 PSIG. One side of
these con tacts is con nect ed to 115VAC. The other side
con nects to I/O Board TB3-81. The Microboard reads
the state of these con tacts through the I/O Board and
when they open, a safe ty shutdown is performed and
“THRUST BEAR ING – LIMIT SWITCH OPEN” is
displayed on the System Details line of the Display. On
the COM PRES SOR Screen, a red LED illuminates when
the switch is closed; ex tin guish es when it is open.
After the High Speed Thrust Bear-
ing safe ty shut down has occurred,
the chill er can not be re start ed until a
Thrust Bearing inspection, followed by
a special reset pro ce dure which has
been performed by a qual i fi ed Ser vice
Tech ni cian. The re set procedure and
Bear ing in spec tion cri te ria is listed
in the “System Cal i bra tion and Reset
Pro ce dures section of this book.
FIG. 49 – HIGH SPEED THRUST BEARING LIMIT SWITCH - INTERFACE
LD06866
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