Vibration Trip

A

Thread Starter

Adeel Imtiaz

Greetings,

We have MARK-V Control system on FRame-5 25MW gas turbine. We also have a trainer for MARK-V simulation. We simulated gas turbine complete start-up. During Trip checks I disconnected all three Vibrtion probes 39V1, 30V2 & 39V3 but gas turbine did not trip. Is this normal behaviour of vibration circuit?

Regards,
Adeel Imtiaz
 
Adeel Imtiaz,

A "trainer" for Mark V simulation can be a "suitcase" trainer or it can be a full-blown Mark V panel. Neither would have vibration pick-ups connected to it for simulation (there is a block called KILL_IO to turn off the I/O during simulation).

So, if you were doing this with the Mark V connected to the turbine it's not clear how you simulated the start-up. Please be more specific about the circumstances. Were you working with the Mark V controlling the turbine? Were you working with the suitcase trainer, or a full Mark V panel being used as a simulator? Were you doing this during a START, or after the unit had reached FSNL? Please be as specific as possible.

Having said all of the above, there are two mask values that have to be set properly for the Vibration BBL to work properly. It's, unfortunately, all too common to find they were not checked during commissioning and left with the proper values. The two masks tell the BBL how many pick-ups are connected to the Mark V, and which ones are redundant, and then the BBL knows how to trip the unit based on redundancy or non-redundancy, alarm on loss of feedback, etc. At this writing, I do not have access to any Mark V information so I don't know what the names of the two Control Constants that are the vibration BBL masks. If you can find the two masks, and provide their values, along with the number of pick-ups on each bearing of the turbine, the reduction (load) gear, and the generator we could probably tell you if the mask values are correct for your turbine. You will also need to provide the name of the vibration BBL (it's at the top of the block in the CSP).
 
Adeel bhai;

Initially there are two types of vibration measurement are used in Mark V control system.

One is seismic type other is displacement.

Displacement type vibration have tags like 39VS11, 96VC11.....& there is no tripping of gas turbine on actuation of it.

Second is seismic type which has tag numbers like BB1, BB2,...& there is tripping.

So, you check your logic configured in trainer first.
Secondly do it with your running turbine & see the difference.

Regards,
Farhan Mazari
 
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