ONE-DIMENSIONAL MODEL FOR NONLINEAR STRESS-CONTROL IN CABLE TERMINATIONS

A one-dimensional model for field control in cable terminations is ana lyzed mathematically both for linear and nonlinear field grading mater ials. For an applied ac voltage, the concept of the penetration length allows for a useful characterization of the voltage profile, even for materials where both the conductivity and the permittivity are field dependent. For lightning impulse events an analytical solution for pur ely resistive field control is presented, allowing for an arbitrarily strong nonlinearity of the conductivity. The model results yield a use ful input for more detailed finite element calculations. The results s how that conclusions for nonlinear field control based on linear calcu lations in general are misleading.