Internal discharge patterns in faulty insulators

There are many methods to be developed in detecting faulty porcelain suspension insulators. The method by measuring the corona and internal discharge pulses at the end of the insulator string or on the ground is discussed. The characteristics of these discharges were understood by simulating defects inside the insulators and were compared with those of corona discharges. Results on the simulating defects showed that the starting-up voltages of the internal discharges, the wave-shapes, the phases of discharge pulses and the pulse amplitudes varied with the kind of defects. Furthermore the internal discharge patterns of insulators with different types of defects were investigated. In the end, the advantage and the limitation of the method to detect faulty insulators based on the internal discharge and corona pulses were analyzed. A new idea of detecting faulty insulators was proposed.