Switching surges

For analyzing a very fast front surge (switching surge in a gas-insulated bus) or a lightning surge, stray capacitances of a CB between poles and the ground have to be considered. 

Generation of harmonics and switching surges in a static device switching circuit 6/129... 

Switching of welding transformers these may cause dangerous voltage surges. 

Voltage surges, caused by system disturbances or switching operations (for HT motors). 

Switching surges, as may be caused during the switching operation of an inductive circuit (Section 17.7,2) or a capacitive circuit (Section 23.5.1)... 

Protection of rotating machines from switching surges 17/578... 

The need to protect a rotating machine from switching surges, contact bouncing and surge transferences 17/576... 

These are mainly due to atmospheric disturbances as noted below. The effect of such surges is totally different from that of switching surges, and the amplitude is independent of the system voltage. 

For a voltage impulse having a front duration of more than 30 /is (normally switching surges)... 

X time taken by the impulse to rise from 0% to 95% of its peak value For the sake of laboratory testing and analytical studies, these surges have been represented by standard impulse waveforms. According to lEC 60060-1 a 1.2/50 /is impulse is called a standard lightning impulse, and a 250/2500 /is impulse a standard switching impulse. 

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