GE 9FA Gas Turbine Fan When Running Standby Fan Getting Reverse Rotation


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My plant GE 9FA gas turbine 88TK fan and 88BT fan when running standby fan getting reverse rotation due to damper passing which is leading to motor burnt. Please advise me how could I solve?

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Have you tried fixing the dampers? Usually they get mechanically bound/stuck and/or rusted, which prevents them fully from closing by the damper weights. Sometimes, the weights vibrate loose, or are misadjusted. Other times the dampers or the mechanisms get bent during fan removal and reinstallation when maintenance outages are performed.

But, when properly adjusted and maintained (including lubrication, if necessary) they usually provide decades of reliable service.

There have been a couple of sites that have sourced and installed sealed bearings on the damper shafts to mitigate most problems--except when the dampers are bent or damaged during fan removal and re-installation during maintenance outages.

Short of these very simple things, you could run more wires in conduit from the Speedtronic and add logic and outputs to the Speedtronic to drive motor-operated dampers. But, they, too, require basic periodic maintenance and possible adjustment--but have all the benefits of being more complicated and more difficult to maintain and require more spares and work to initially install, and to remove and reinstall when performing maintenance outages. And they, too can still be damaged during fan removal and reinstallation.

Or, perhaps you're referring to motor-operated dampers used by the GE Belfort Bunch who consistently and needlessly over-complicate things whenever possible? You didn't say if the dampers were gravity- or motor-operated.

But, in either case it would appear there is a lack of basic maintenance for "the dampers" which have historically been adequate and simple--when properly maintained and adjusted. And, little improvements like sealed bearings can go a long way to improving operation and reliability--as can basic maintenance.