Thanks, I must admit I wonder how mains transients are such a problem, even where high current switching takes place.
Suppose there is 500A flowing in a mains cable and the mains cable inductance is 20uH.
Then the energy is 0.5*L*I^2*t
Now consider that this inductive current circuit gets broken.
Now also suppose that nearby on the same phase there is a 220uF capacitor bank downstream of a PFC stage (obviously also downstream of a mains rectifier etc).
Considering a 10us spike interval, then the power to be dissipated is 250kW.
Supposing the capacitor bank has 380VDC on it….
Then that equates to 658A (VIt = 0.5*L*I^2*t) flowing for 10us. That would take the capacitor bank voltage up by only 30V…….hardly a problem, and when you consider that there are other devices connected to the mains, each with their own capacitor bank, it makes you wonder how mains transients ever rear their ugly heads at all?
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