Degradation of Metallized Film Capacitors under Co-60γ Radiation

As an energy storage element, capacitors are gradually being used in various complex environments. When subjected to high-energy radiation, the internal and surface of the dielectric material wilt accumulate charges and cause discharge, and it will cause irreversible changes in the physical and chemical structure of the dielectric, which will affect the performance of the capacitor. In this paper, polypropylene film and metallized film capacitors have been tested, and the effect of gamma-ray irradiation on the crystallinity of polypropylene film, the basic parameters of metallized film capacitors (relative permittivity, dielectric loss and ESR), voltage maintaining performance and space charge polarization characteristics are studied. The preliminary results show that when the total radiation dose is small (less than 100kGy), the relative permittivity of the capacitor does not change significantly before and after the radiation. When the absorbed dose reaches 1000kGy, the relative permittivity of the capacitor decreases by 5.1×10-1%; irradiation will cause the voltage maintaining capacity of the capacitor to decrease. When the absorbed dose increases from 0kGy to 1000kGy, the voltage drop within 10s of the capacitor increases from 1.62% to 6.54%; with the increase of the radiation dose, the crystallinity of the film gradually decreases, and the space charge polarization degree of the metallized film capacitor gradually increases. When the radiation dose increases from 0kGy to 1000kGy, the film crystallinity changes from 48.56 reduced to 34.52%, Q/A increased from 0.5 to 3.56.