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We are facing an issue at our running unit frame 5 gas turbine driving generator w.r.t to intermittently increased seismic vibrations at BB2 (Compressor Casing Inlet) and BB1 (Bearing No. 1). The values at BB3 point (Pedestal Bearing) remain normal during these events.
Other unit is under maintenance, and subject unit is running in ISO mode. Normal values at BB1 & BB2 are 0.8 & 2.8 mm/sec, respectively.
HIGH VIBRATION EVENTS to date (from 13 Feb to 17 Feb). The vibrations at BB2 increased from normal 2.8 to 7.5~8 and returned gradually to normal.
All the event lasted for ~10 minutes, and values returned to normal at BB1 and BB2. The values reduced gradually in interval of o.mm/ sec. The local vibrations at the time of last event were noted and found increased from 3.1 to 3.6.
The setting on Mark-V is 12.5 mm/sec for alarm and 25 mm/sec for tripping. (Max values out of BB1, BB2, and BB3). VTs are installed at BB1, near Rigid coupling of generator and pedestal bearing. Except the erratic value of BB1, other values of VTs at BN-3300 are normal (15-35 microns). The thrust value is also normal at BB1 is 7 to 8 mils. During these events, no change was observed in any other parameter (TG load, speed, CWS temperature & pressure, Lube oil supply temperature & pressure, exhaust temperature).
Compressor side primary filters were replaced one month ago, and condition of secondary filters were also good. All the events occurred in daytime with ambient temp range from 22 to 28 deg c.
Please discuss about possible causes and checks during operation of the machine.
Thanks & Regards
Other unit is under maintenance, and subject unit is running in ISO mode. Normal values at BB1 & BB2 are 0.8 & 2.8 mm/sec, respectively.
HIGH VIBRATION EVENTS to date (from 13 Feb to 17 Feb). The vibrations at BB2 increased from normal 2.8 to 7.5~8 and returned gradually to normal.
All the event lasted for ~10 minutes, and values returned to normal at BB1 and BB2. The values reduced gradually in interval of o.mm/ sec. The local vibrations at the time of last event were noted and found increased from 3.1 to 3.6.
The setting on Mark-V is 12.5 mm/sec for alarm and 25 mm/sec for tripping. (Max values out of BB1, BB2, and BB3). VTs are installed at BB1, near Rigid coupling of generator and pedestal bearing. Except the erratic value of BB1, other values of VTs at BN-3300 are normal (15-35 microns). The thrust value is also normal at BB1 is 7 to 8 mils. During these events, no change was observed in any other parameter (TG load, speed, CWS temperature & pressure, Lube oil supply temperature & pressure, exhaust temperature).
Compressor side primary filters were replaced one month ago, and condition of secondary filters were also good. All the events occurred in daytime with ambient temp range from 22 to 28 deg c.
Please discuss about possible causes and checks during operation of the machine.
Thanks & Regards