4. Study of slow-front surges

4.1 Context

According to , for systems where the highest voltage for the equipment is below 245 kV (IEC rank 1), slow-edge surges are generally not critical, whereas lightning surges require careful consideration. For higher voltage levels (IEC Rank 2), slow-head surges are important to study, while temporary surges are often less critical. Lightning surges must be considered for all voltage levels.

Studies of slow-head (maneuvering) overvoltages...