brief introduction: Choke coil is a ferrite core of common-mode interference suppression devices, it is made up of two same size, same number of turns of the coil symmetrically on the same ferrite ring core, forming a four terminal device, to the common mode signal present a large inductance with inhibition, and for the differential mode signal present a little small leakage inductance.Choke coils can effectively suppress common-mode interference signals (such as lightning interference) in balanced lines, but have