Performance Evaluation of Insulating Links Used for Worker Protection in Cranes

Insulating links are used to protect crane workers from accidentally contacting a transmission line. This paper presents the results of laboratory tests that determined the leakage current produced by sudden energization of polluted and wet insulating links. Two different manufacturers´ links were tested at heavy and light pollution. The results show that the short duration transient or the root mean square (rms) leakage current is the measure of the ability of the links to provide protection. The leakage current can endanger the life of a crane worker before flashover occurs. The dependence of leakage current on test voltage under heavy and light pollution conditions was determined. Obtained leakage current data was compared with IEC 479-1 standard, that provides health effect data. The link protects the crane worker, if the line voltage is less than the maximum voltage determined from the correlated test results. The results were used to assess the efficiency of worker protection.