Proposal of a dynamic numerical approach in predicting flashover critical voltage

Abstract

<span lang="EN-US">Glass insulators, due to its diverse characteristics, were used widely around the world for high voltage transmission lines. Surfaces of the insulators are exposed to high electrical, mechanical, and thermal stresses over the period of service. Accumulation of contamination distort stresses distribution along the insulators that may lead to flashover under severe condition. In this paper, Obenaus pollution model has been adopted to propose a dynamic mathematical modelling to determine flashover critical voltage with regard to parameters such as pollution conductivity, arc length, and width of layer of contamination on the surface of glass insulator. In addition, laboratory experimental works have been carried out according to IEC60305 to validate the results from numerical approach, which indicate a good agreement.</span>

Surface roughness condition of field-aged polymer insulators at different installation area

“…At the beginning, the four points of arithmetical mean surface roughness, Ra data for each ten fieldaged sample are recorded. Then the sample mean of Ra ( ̅ a ) and sample standard deviation of Ra (sRa) are calculated using the (7) and (8) respectively [22]. sample mean of Ra:…”

“…It is inevitable factor which depends on the local climate and pollution condition that was experienced by the outdoor insulators at the field of service. These multiple stresses vigorously accelerate degradation that will cause surface tracking [1], weight loss or erosion [6], loss of surface hydrophobicity [7], partial arcs discharge, and increase an electrical leakage current (LC) [8] or complete failure [9].…”

Risk Assessment of Polluted Glass Insulator Using Leakage Current Index Under Different Operating Conditions

“…So the requisite PFDs will be the probability of Flashover occurrence as a function of LC index R hi and the probability of LC index R hi existence as a function of this index. According to (15) the flashover occurrence probability can be computed as a function of the LC index as an indicator of the pollution severity.…”

“…where S is insulator risk, f(R hi ) as defined in (15) and P(R hi ) as defined in (16). Figure 17 shows the risk (S) calculation of both the uniformly polluted insulator strings used under W r is 2.5±0.1 l / h and z = 1/3.…”

“…All these phenomena increase the magnitude of leakage current (LC) flow over the insulator surface. Thus, the assessment of outdoor insulator properties and its long-term performance is a hot topic for investigation by many researcher [15]- [21]. One particularly issue of interest is that to establish an accurate relationship between the LC and pollution severity while the insulator is in service.…”