PROJECT TITLE :

Polarization characteristics of metallized polypropylene film capacitors at different temperatures

ABSTRACT:

When the metallized polypropylene film capacitor (MPPFC) is employed underneath high electric field in pulsed power systems, an apparent voltage decay phenomenon will occur. The voltage decay is especially resulted from the relief polarization in dielectric applied underneath high electric field. This paper focuses on the comfort polarization in metallized biaxially oriented polypropylene (BOPP) film capacitors. The extended Debye model of relaxation polarization is discussed and therefore the parameters of every RC branch are obtained. Meanwhile, the connection between the increasing proportion of polarization charge (ΔQa/Qh) and temperature is investigated. The experimental results show that beneath 1kV, ΔQa/Qh varies from zero.018 to 6.868 with the temperature varing from 10 to seventy /spl deg. Moreover, the equivalent capacitance of capacitors in frequency domain is analyzed with consideration of slow polarization. The analysis shows that each a lower frequency and a better temperature can accelerate the comfort polarization and increase the voltage decay. Based on the extended Debye model developed from the polarization charge take a look at, the voltage drop is calculated and the results will match well with those of the voltage maintaining check.