For big steam turbine ( from 200MW), for reverse power functionality, we used only CT meas. class, it must. Seeting about 0.5% of Pnom.
DPC, remind very important point. I see in new turbine (w/o name), instead main steam valve limit switch some calculation of flow and data from several sensors, for my pinion not so good solution.
Against operators problem, we used " wait time" solution, block of reverse power protection for some time after CB close position.
Regards