KEMA (Netherlands) developed a method for using partial discharge (PD) to locate weak-performing cable circuits. Utilities in Asia, Europe, North America and the Caribbean have adapted this method. Users report a reduction of financial losses related to non-delivered energy. Measurements of problem circuits have shown that large investments could be postponed to a later date.

The measuring and locating of PDs on circuits ranging from 100 m to 6000 m (328 ft to 3.7 miles) circuit length locates weak spots in the circuit. This method has been extended to include branched cable circuits. While measuring more than 6500 km (4039 miles) circuit length all over the world, it became clear that cable joints and terminations are the weak spots in more than 90% of the cases.

The PD diagnostic method has proved to be a powerful tool for performing condition-based maintenance on medium-voltage cable networks.

Dutch utility REMU began performing the PD diagnostic method in 1994. The total circuit lengths measured to date is 712 km (442 miles) with a total of 451 circuits evaluated. REMU repaired 117 joints along with 10 cables. Thirty-two circuits did break down during measurement as the condition of these circuits were very poor. The number of substations with prevented outages was 821. The total savings in labor over five years was 60%. The availability of the circuits increased, financial claims decreased and investments focused on those parts of the network that needed the most attention.
Circle 176 on Reader Service Card