York YK-EP Operation And Maintenance Manual page 213

Microboard where the unbalance calculation is performed. This safety shutdown is not performed
on Electro-Mechanical Starter applications.
Thrust Bearing – Proximity Probe Clearance
The clearance between the compressor high speed thrust collar and the tip of the Proximity Probe
has increased more than +10 mils or decreased to less than -25 mils (for 2 continuous seconds)
from the Reference Position. The minimum allowed clearance is 23 mils. Therefore, if the Reference
position is less than 47 mils, the shutdown will occur when the actual clearance is less than 22 mils.
The clearance is only checked during the last 20 seconds of System Prelube, during System Run and
during coastdown. Therefore, the fault is only detected during those periods.
This shutdown must be evaluated by a qualified Service Technician prior to starting the chiller. Starting
the chiller without this evaluation could result in severe compressor damage. To prevent the chiller
from starting without the proper evaluation, restart is inhibited until the clearance is within acceptable
limits and a special reset procedure is performed by the Service Technician. The evaluation and reset
procedure are contained in OptiView Control Center - Service Instructions (Form 160.54-M1).
Thrust Bearing – Proximity Probe Out Of Range
The clearance between the compressor high speed thrust collar and the tip of the Proximity Probe
has decreased to less than 17 mils.
The clearance is only checked during the last 20 seconds of System Prelube, during System Run and
during coastdown. Therefore, the fault is only detected during those periods.
This shutdown must be evaluated by a qualified Service Technician prior to starting the chiller. Starting
the chiller without this evaluation could result in severe compressor damage. To prevent the chiller
from starting without the proper evaluation, restart is inhibited until the clearance is within +10 to -25
mils of the Reference Position and a special reset procedure is performed by the Service Technician.
The evaluation and reset procedure are contained in OptiView Control Center - Service Instructions (Form
160.54-M1).
Thrust Bearing – Limit Switch Open
The High Speed Thrust Bearing Limit Switch contacts, connected to TB3-81, have opened. This
occurs when the Bearing position decreases to less than the allowed position.
This shutdown must be evaluated by a qualified Service Technician prior to starting the chiller. Starting
the chiller without this evaluation could result in severe compressor damage. To prevent the chiller
from starting without the proper evaluation, restart is inhibited until the switch contacts have closed
and a special reset procedure is performed by the Service Technician. The evaluation and reset
procedure are contained in OptiView Control Center - Service Instructions (Form 160.54-M1).
YK-EP Style B Centrifugal Chiller
CAUTION
CAUTION
CAUTION
213