An online indication of vibration monitoring was cause unit GTG to trip with triggering an indication of high vibration at the cooler fan. The fan bearing was covered due to that measurement was initially perform at the fan structure and found the vibration was genuine. A further request to remove fan cover was made in to order to place accelerometer directly on bearing pedestal surface. The spectra results show dominated by non-synchronous element. For further analysis of this problem, the bearing number was requested. However, both bearing fans were tempered with OEM nameplate and no bearing ID were obtain. Time waveform analysis were investigate carefully and found modulation nature with the rate of shaft turning speed. Thus, it was determined that both cooler fan having an inner defect and decision to replace both bearings is made. Few months later, the new bearing was installed feedback were received from operation with the statement that absolutely machine is okay.
Monthly trending sudden increase at air end side. Vibration spectra were noticeable by the element of Male Screw Mesh Speed at axial direction. Further investigation was performing by study the machine maintenance history. There is few elements were due for replacements and regular service. After regular maintenance was performed, significant vibration improvement had achieved.