Switching Surge in DC Circuits

Basic characteristics total 21 cases due to SS within dc circuits 13 

All the disturbances are in the voltage class of 154 kV and lower. The reason for this is estimated due to more coimtermeasures to reduce the surges in a higher voltage class. 

Disturbed equipments telecommimication 7, protection 3, control 3 The reason for more disturbances in the telecommunications is that the equipments have more connection with CB control 

The reason for the seven cases in the telecommunication equipments is estimated due to switching overvoltages higher than the voltage defined in a standard or the parts that are not defined in a standard [15,16]. 

The aforementioned ratio of the disturbed elements is similar to that in the disturbances due to main-circuit switching surges except the auxiliary relays, which is characteristic to the dc switching surges. 

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