Bently Nevada Alarm Causing Turbine to Trip

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Thread Starter

azlan

Hi there..

I have issue on our BN. Recently One of displ. probes (L232-HIGH SPEED SHAFT) on the load gear box was activated and reach max level causing our gas turbine to trip. When checking on the BN monitor, the 1st alarm come out (yellow) then we raised up the loading hopefully to lower the vibrations (from15MW to 25MW). but the thing getting worst when BN show that the vibration reached at max (red). is it possible the alarm signal sent to the relay that may cause our gas turbine to trip? Upon checking on our gas turbine Marx V it only stated trip on bently nevada rack and displ. probes BN high speed alarm. After the GT was trip, we tried to start it back but not reaching FSNL, the L232 activated again reach max (red).
 
Yes, it's possible and very likely.

You can use the Marx V Alarm Drop Number and the ALARM.DAT file to determine the CSP signal that caused the alarm and the trip, and then use Dynamic Rung Display to verify the B-N Danger relay output does indeed trip the turbine. This should also be visible on the Trip List Display (a list of all trips--one of them will likely be from the B-N monitor).

Does the Marx V have seismic vibration pick-ups on the gear box? If so, did they indicate high vibrations? (There might be some limited data on the Marx V Trip History display.)

Have you verified the proximity probe is good? B-N vibration systems need a speed signal, usually from a keyphasor. Have you verified the keyphasor signal is good?

Has anyone been in the area of the gearbox to detect if there is truly a vibration problem?

Lastly, it's been my personal experience that increasing load when vibrations are high almost never causes vibrations to decrease, but rather to increase. It's generally accepted practice that if a machine must be run with high vibrations that the load must be reduced, and even gradually reduced until the machine must be shut down to investigate and resolve the vibration issue.

Please write back to let us know what you find.
 
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