Regions of electrical stress in high voltage capacitor units

As electrical systems develop, and power electronic converter interfaces proliferate, greater reliance is placed on the capacitor units which comprise them. For such applications, resilience to electrical stresses is essential to capacitor unit design, as electrical field stresses can degrade insulation and cultivate incipient faults. Left unchecked, insulation can breakdown and cause an associated reduction in capacitance, an increased reactance, and subsequently greater electric field stresses and susceptibility to further ‘cascading’ failures. COMSOL Multiphysics’® AC/DC module is used in this study to emulate electric field stresses throughout a simplified capacitor unit. Regions of electrical field stress are highlighted using an electrostatics boundary condition so that: their impact and implications for fault progression can be considered for engineering design; and to inform maintenance activities of where degradation is anticipated. While this study uses a simplistic capacitor model of homogenous dielectric, few winding turns, and omits noise inherent to real applications, it could offer limited insight into physical influences within enclosed assets which are presently becoming increasingly pervasive in electrical infrastructure. Configurability is also discussed as a means to enable study of alternative designs.