Onsite MOSA condition Assessment-a new approach

A new method to assess the condition of metal-oxide surge arresters is presented. The fundamental component of the resistive current is used as an indicator. This current is obtained by exploiting the linear relationship, which exists between the peak value of the fundamental component of the resistive current and the phase shift between the fundamental components of the capacitive current and the total arrester current. This relationship is independent of temperature for a given type of arrester. Results are presented to demonstrate the accuracy and the reliability of the new technique.