YORK YK — Thrust bearing - Proximity probe clearance

The panel shows Thrust bearing - Proximity probe clearance. The manual lists it among the safety fault messages, and it only applies to compressors that use proximity thrust bearing protection.

The clearance between the compressor high speed thrust collar and the tip of the proximity probe has moved too far from its reference position: it has increased more than 10 ml or decreased to less than -25 ml, held for 0.2 s. The minimum allowed clearance is 23 ml. As the manual's example states, if the reference position is less than 47 ml, the shutdown occurs when the actual clearance is less than 22 ml. The clearance is only checked during the last 20 s of system prelube, during system run and during coastdown.

• The clearance between the compressor high speed thrust collar and the tip of the proximity probe has increased more than 10 ml from the reference position.
• The clearance has decreased to less than -25 ml from the reference position and stayed there for 0.2 s.

1. CAUTION: a qualified service technician must evaluate this shutdown before the unit is started again.
2. Restart stays inhibited until the clearance is back within acceptable limits; the fault is released when the proximity position is less than +10 ml or greater than -25 ml from the reference position, or the proximity position is greater than 22 ml.

• Trip condition: clearance increased more than 10 ml or decreased to less than -25 ml from the reference position, sustained for 0.2 s.
• Minimum allowed clearance: 23 ml.
• Manual example: if the reference position is less than 47 ml, the shutdown occurs when the actual clearance is less than 22 ml.
• Monitoring windows: the last 20 s of system prelube, system run and coastdown.
• Release limits: proximity position less than +10 ml or greater than -25 ml from the reference position, or greater than 22 ml.

Two things must happen before the message goes away. First, a password is required to acknowledge the fault on the Proximity Probe Calibration Screen. Then, the message is released when the compressor switch is placed in the stop position and the Clear button is pressed next to the listed event on the Systems Details Screen. CAUTION: restart is inhibited until the clearance is within acceptable limits and a special reset procedure is performed by the service technician.