What are the classes of trips based on the seriousness of a particular fault, the turbine has to be tripped or a generator has to be tripped or the complete system has to be shutdown? Is there a classification of all those types of faults? Finally, any online material which can be referred to for this? Any help will be appreciated.

 

There are three classes of tripping (in 210MW generators). Master trip relay (86) is used for all classes of trippings. The classes are:

1. Class 'A' (86A1,86A2,86A3): First Generator trips and then turbine trips.

2. Class 'B' (86B): First Turbine trips, then Generator trips.

3. Class 'C' (86C): LBB tripping, etc., normally tripping signals are from the system.

The classifications of class 'A' tripping such as 86(A1,A2,A3) depends on various parameters in the power plant.

I hope the above details will give you a brief idea about the tripping classes.