Accelerated aging test on multiple XLPE MV cables simultaneously to induce water trees

The objective of this paper is to develop an accelerated ageing test to induce water tree growth which is capable of testing up to ten 10 kV cable samples simultaneously. An existing accelerated ageing method was used as a basis for this project. This method uses a high frequency power supply (3 kHz) to achieve a test duration of 14 days. Modifications were made to this method to allow for multiple samples to be tested simultaneously. A specially designed variable inductor was utilised in a parallel RLC resonance circuit. This resonance circuit limits the current draw from a high frequency high voltage transformer which allows for up to ten sample to undergo the test. Water trees were found in a number of the samples tested. The maximum length and quantity of water trees in each sample was recorded and analysed. A ranking system was used to grade how each cable preformed during the test. The method of using the parallel resonance circuit to limit the current was successful. The accelerated ageing test worked as expected and water trees were detected in tested cable samples.