Fault Phenomenon: CAT rotary drilling rig instrument displays borehole depth that deviates significantly from the actual depth, affecting construction accuracy.

Troubleshooting Process:
– Checked encoder: rotary encoder on winch shaft loose or damaged.
– Checked rope diameter setting: wire rope diameter parameter set incorrectly in system.
– Checked wire rope: wire rope elongation not compensated.
– Checked sheave: measuring sheave slipping.

Root Cause: The rotary encoder measuring winch rotation is loose, causing the encoder shaft to rotate asynchronously with the winch shaft, resulting in counting errors.

Required Parts: Retighten or replace rotary encoder, recalibrate depth.