IEC TS 61463 pdf download Bushings – Seismic qualification 1Scope This technical specification is applicable to alternating current and direct current bushings forrated voltages above 52 kV，mounted on transformers,other apparatus or buildings. It isaccepted that for bushings for rated voltages less than or equal to 52 kV, due to theircharacteristics (resonance frequency greater than 25 Hz) seismic qualification is not...