we have one 15 MW steam Turbine which was tripping on under frequency in steady state without any addition of load. This phenomenon was repeating frequntly giving no clues. The tripping is at random and sudden and no chance for saving the turbine from tripping. The following checks were carried out both by O & M Team and OEM.
1) AVR was checked found OK
2) Electronic Governor checked no problem noticed
3) Generator Protection Relay (Beckwith Make) checked tripping the set on actual low frequency parameter.
4) Mechanical side checking like governing oil filter, nitrogen pressure of accumalator
etc were done but no clues for tripping.
5) At lat I /H Converter was changed
but unfortunately testing of 5th point could not be done as generator tripped on rotor earth fault, during this period turbine was also opened and found that 7 nos of Curtis wheel blades were missing, after repair work of both turbine and generator machine was put back on service. after restarting we are not experiancing any under frequency tripping.
now the question is whether the problem was with I/H converter or Curtis missing blades is not clear, can any one think and revert.
Steam Turbine Tripping
Re: Mechanical
