High Vibration Tripping of Gas Turbine


Thread Starter


we have five Hitachi make H25 gas turbine in GT-1. we are facing a problem of High vibration tripping.

it start few month back when we reduced load (normally kept at base load) on GT-1 vibration in bearing Two which is between compressor & Gear box side. Bearing start increasing gradually simultaneously no-1 bearing vibration start following this and m/c trip on high vibration 155 micron.

even after tripping vibration increasing in all probes of both bearings till they get out of range, metal temp, Lo drain temp are all well within range.

after inspection with GE engineer we started machine again nothing was found. During start up high casing vibration (no tripping given) observed which is new in machine after startup vibration was also ok till base load, machine kept in service for almost a month. but again machine trip with the same phenomenon while reducing load.
can any one having any clue?
What type of vibration probes?

This may sound strange but, rotor ground brush may be at fault.

Two possibilities:

loose causing rattling
complete non-contact causing static charge build-up, which affects the proximity probes. (Hall effect)