Simulation of electro-thermal ageing and breakdown in polymeric insulation under high frequency trapezoidal-wave pulses

Abstract

A quantitative ageing model expressed in terms of two generic parameters, one describing the ability of local regions to resist degradation and the other describing their capacity to concentrate energy from the electric field, has been used to simulate the electro-thermal ageing of Polyethylene Terephthalate (PET) in pulsed trapezoidalwave electric fields. Allowance has been made for the dielectric heating produced by the alternate-polarity voltage pulses. It was found that for 90% of the lifetime the degradation was that of isolated regions. Only when the regions started to group to produce a local field in excess of a critical value did the degradation accelerate to failure in the form of a single track. The critical field is associated with the effective onset of irreversibility in the production of degradation, such that a local equilibrium state in the presence of the field was no longer possible regardless of the nature of the surrounding material. The temperature increases were found to be small and had very little influence upon degradation formation, though they had a minor influence on the initiation of runaway failure.

Analysis of the Electric Field-Dependent Current During Electroporation Pulses

“…Initially, the electric dipoles polarize rapidly due to the rapid rise in the applied electric field, which results in a dramatic initial current increase (Figure 1). However, when the applied electric field reaches a constant value, the polarization then gradually reaches equilibrium, slowing the change in the current [32]. Therefore, when an electric field is applied to the DMEM without cells, the current initially increases and then quickly decreases exponentially until it stabilizes ( Figure 2).…”

The fragmentation mechanism of granite in electrical breakdown process of plasma channel drilling

“…The time from initiation to complete formation of the plasma channel is actually extremely short, generally in nanoseconds to microseconds. (Otsuka et al 2007;Zuo et al 2018). On account of the complex structure of rock and the interference of strong electromagnetic and strong light, it is very difficult to monitor the rock-breaking process of PCD and obtain physical and mechanical information.…”

Modeling for life estimation of HVDC cable insulation based on small-size specimens

“…Although temperature has not been addressed here as a variable, different temperature laboratory tests on thin films would allow ∆G to be separated into values for ∆H and ∆S, since ∆G = ∆H -T∆S, and hence simulations could be carried out for service condition temperatures, and even temperatures that are not spatially uniform. Dielectric heating can even be included in the simulation if necessary [26]. All these features mean that the method can be developed as a potent engineering tool for life prediction.…”