PD-Behaviour of Electrical Treeing in XLPE at Different Kinds of AC Test Voltages

摘要

Electrical Treeing (ET) is one of the mainrnphenomena endangering the reliable function of PE orrnXLPE insulated cables. During on-site testing of a cablernET can remain undiscovered in cases where it does notrnlead to a breakdown during a plain voltage withstand test.rnResearch work was done in the past to determine thernspeed of growth of ET not only for test voltages withrnpower frequency but also for alternative test voltages e.g.rnVLF (0.1 Hz) which are used for on-site testing ofrnmedium voltage cables.rnHowever, two recent developments raised new demandrnfor research activity in this matter: PD measurementrnsystems were added to equipment for on-site testingrnmake the results of voltage withstand tests more reliable,rnand the use of resonant test sets with variable frequencyrnbecame more and more common. Therefore the PDrnbehaviour of ET is investigated in this work at testrnvoltages in the whole frequency range from 0.1 Hz up torn100 Hz. Furthermore the shape of the test voltagernvaried to get a deeper insight in the physical processesrnthat occur during Electrical Treeing. A special highrnvoltage test generator was developed and realised duringrnthis work to be able to produce almost any test voltagernshape in the frequency range from DC up torn1 kHz andrnwith peak voltages up to 60 kV at 100 mA.