Computer package for selecting high voltage insulators for different contamination conditions

Creeping discharges features propagating in air at atmospheric pressure on various materials under positive lightning impulse voltage – part 2: modelling and computation of discharges’ parameters

“…Many attempts have been made to suggest propagation mechanisms and to describe the discharges motion on polluted material surfaces especially leading to extract some formulations for the discharge velocity computation. In this section, we have first computed the discharges velocity growing on material/air interfaces based on two analytical expressions namely (i) one formula elaborated by Beroual [58] expressed in (7) and used by several researchers [59][60][61][62][63][64][65][66][67] (ii) and another formula found out by Les Renardières Group [68][69][70] and expressed in (9), because of the good agreement they both provide regarding experimental data. Then, calculation results were compared to those obtained empirically through (11) with regards to tested materials…”

Electro‐thermal dynamic model using the analytical arc parameters for the prediction of the critical flashover condition on the HVDC polluted insulator

“…Unfortunately, the flashover modelling of polluted insulators still a difficult task since static models are not enable to both describe the instantaneous changes of the discharge parameters and predict all the evolution process of the flashover phenomenon. In addition, there exists few dynamic models that deal with this phenomenon in the literature of flashover insulators (see [8,[10][11][12][13]). That is, since the flashover is considered as a rapid process, it is interesting that the proposed models should take into account the majority of physical conditions that combining electrical, thermal and chemical interactions [12][13][14][15].…”

“…We contribute in this paper to develop a flashover dynamic model of flat plate insulators in which the choice of its two-dimensional representation is justified by the fact that this flashover phenomenon depends essentially on the surface characteristics of pollution layer. In the proposed model, we involve the analytical impedance criterion for the propagation condition [16] and the energetic balance [13,17,18] in order to define the discharge propagation velocities. The approach of resistive equivalent electrical circuit which contains resistors in series (discharge resistance and pollution resistance) is used such as developed earlier by many researchers [10,11,19].…”

“…where V E denotes voltage drops of electrodes which can be neglected [9,13], V arc (X ) represents the arc channel voltage and I means the leakage current. Notice that the unabridged part of the pollution layer R p (X ) is formulated as follows…”

“…This approach gives information's about the voltage that can permit to the arc to reach its critical length (corresponding to critical current) just before flashover [26]. However, these static models are not able to consider all major factors characterising the flashover phenomenon [11,13,18]. Furthermore, it does not consider the dynamic changes of instantaneous parameters characteristics of the system such as leakage current, arc temperature, elongation, arc resistance and pollution resistance which are the most important parameters for pollution monitoring.…”