Diagnostic of silicon carbide surge arresters

The gapped silicon carbide (SiC) surge arresters are being removed from the operating system of the utilities, however, a large number are still installed in the power system. Therefore, it is very important to give priority to SiC surge arresters that are more degraded in order to replace them by the zinc oxide (ZnO) ones. This work shows that the leakage current measurement, normally used as diagnostic technique for the ZnO surge arresters, can also provide important information concerning the condition of the SiC surge arresters. Results from the laboratory tests and substation measurements are presented.