Insulation Failure Mechanism of Dielectric Film for Power Capacitor in Strong Electromagnetic Field

In this paper, the dielectric properties of the polypropylene (PP), polyimide (PI), polyvinylidene fluoride (PVDF) and polyethylene (PE) are investigated in the 0 - 12 T magnetic field. The dielectric constant declines with the enhancement of the magnetic field. At 0.1 kHz, the relative permittivity of the PVDF decreases from 12.2 to 11.5 under 12 T. The leakage conductivity increases by 230% - 372% under the 12 T magnetic field and the breakdown strength is reduced by 17% - 22%. The magnetic field causes the decline of the dielectric insulation performance by exciting charges and suppresses the polarization process by applying force on the electrical dipoles.