Because of distribution network are fitted with plenty of distribution transformers

switch instant

all magnetizing inrush current of transformers are superposition to form a complicated magnetic transient process. On the time of system resistance reduced and time constant increased

magnetizing inrush current will become a larger to cause protection malfunction. The related data and recorded waveforms in magnetizing inrush current tripping are introduced in this paper. For interference suppression of magnetizing inrush current

a new method which is based on a notch filter is presented. The test results show that the method above-mentioned can suppress the inrush current tripping accidents effectively.