Fast-Front Overvoltage, FFO IEC and IEEE
Transient overvoltage usually unidirectional, with time to peak between 0,1 µs to 20 µs, and tail duration < 300 µs.
Transient overvoltage usually unidirectional, with time to peak between 0,1 µs to 20 µs, and tail duration < 300 µs.