Vahid Abbasi, Ahmad Gholami,
Volume 6, Issue 1 (3-2010)
Abstract
Abstract: The application of electric field theory to widely different aspects of electrical
insulation has led to more understanding the phenomena. Electric fields may be considered
as the main reason for insulation failure. The purpose of this paper is to modify importance
of analyzing electric field in insulation design. The SF6 circuit breaker is chosen as case
study that encounters critical situations during its application. The other phenomena affects
insulation is the presence of polar species in a non-polar molecular material locally
modifies the polarization energy, thus creating local states (traps) on neighboring
molecules. Results of calculations carried out for arrays of spatially connected dipoles
indicating that local states of a considerable density may be created, modifying the densityof-
states function, and therefore influencing the effective mobility of charge carriers. The
main result of polarization during application in circuit breaker is loss of life. In this paper
the reduction of negative effects of electric field and polarization by choosing a suitable
insulation structure in a 33 kV SF6 circuit breaker according to calculation in critical areas
is investigated that can also be studied in other types of circuit breakers.
