Generator pole slipping

[kuchenig]

I am trying to obtain a better understanding the mechanism of synchrounous generator pole slipping and the failure of diodes. I understand that pole slipping can cause diode failures due to reverse impulses into the field that exceed the reverse voltage withstand of the diodes. My question is: does the degree of excitation prior to the impulse transient effect the susceptibility of the generator to pole slippage? In other words, if the generator is operated more overexcited (more lagging) will there be a greater margin of protection against pole slippage? I reflect upon the point that if no excitation is applied to a sync gen then it can driven above synchronous speed as an induction generator and in that case there is all kinds of 'pole slippage' and presumably no induced voltage damage (admittedly there are no diodes existing in a generator designed as induction type.) But I am trying to understand the mechanism of diode failure and have not yet found a good source of explanation of the dynamics and whether or not there is any protective devices or operation safeguards that can be employed or installed on a generator to reduce diode failures. Thanks