SCAR 10 is used to check regularly the effi ciency of the metal oxide surge arrester in service that are installed on the high voltage transmission and distribution networks. SCAR 10 performs the test according to the IEC standard 60099-5 A1 ED. 1.0 Section 6: Diagnostic indicators of metaloxide surge arresters in service - Method B1 and B2.
SCAR 10 allows to carry out the control while the surge arrester is in service, analyzing by means of a special current clip-on transformer the leakage current in the surge arrester ground connection. The values of this current normally range from fractions of milliampere to a few milliampere, and are characterized by a third harmonic distortion whose value is an indicator of the deterioration of the surge arrester. The resistive component of this leakage current may increase due to different stresses causing ageing and fi nally causing arrester failures.