Effect of Ice Shedding on Discharge Characteristics of an Ice-Covered Insulator String during AC Flashover

Considering the ice shedding phenomena on ice-covered outdoor insulators, this paper conducted the artificial experiments by using a five-unit suspension ceramic insulator string covered with wet-grown ice to investigate the effects of ice shedding on the icing discharge characteristics. According to IEEE Standard 1783/2009, the minimum flashover voltage (VMF), propagation of discharges to flashover and related leakage current (LC) were measured. It was found that VMF after ice shedding can be increased by about 17% as compared with that before ice shedding. The initiation and formation of discharge arcs across ice-free regions caused by ice shedding become difficult, showing an unstable propagating path, indeterminate arc shape and longer arc column. Although VMF under ice shedding conditions is higher than that without ice shedding, the fundamental component, and harmonics show lower amplitudes for the latter case. The ratios of harmonics to the fundamental are well in accordance with discharge characteristics during the flashover for which the ratios show a relatively stable varying tendency in the absence of ice shedding, but show changeable and indeterminate variation under ice shedding conditions. The obtained results are helpful to understand the icing state and its influence on surface discharges for preventing the icing flashovers.

Pāinian accounts of the Vedic subjunctive: le Krvaíte

To determine which Vedic texts Pāini knew requires a comprehensive approach that establishes a high correlation between the complete set of linguistic traits his treatise describes and the complete set of linguistic traits exhibited in each text in question. The examination of individual linguistic traits is inadequate to determine which texts he knew because neither the Vedic nor the grammatical tradition is uniform and static. Bronkhorst (Pāinian Studies: Professor S. D. Joshi Felicitation Volume, p. 75, 1991) calls into question the assumption that Vedic texts were known to Pāini in the form we have received them, while Cardona (Pāinian Studies: Professor S. D. Joshi Felicitation Volume, p. 130, 1991) shows that Pāini's silence concerning certain Vedic forms may be due to deference to certain received exegetical traditions. The current paper considers a case where the Pāinian grammatical tradition entertains disagreement over the derivation of obscure forms. Doubt concerning the recurrence of the term pit (3.4.92) into 3.4.94 brings into question whether Pāini systematically accounts for stem strengthening in the present subjunctive. Kātyāyana, Patañjali, Jayāditya, and Jinendrabuddhi remain silent on the point. Rāmacandra, Śīkria, and Bhaojidīkita assert that pit recurs, thereby allowing stem strengthening. Haradatta, on the other hand, maintains that a rule of indeterminate variation, 3.4.117 chandasy ubhayathā, accounts for it. Nāgeśa points out that the latter procedure is more comprehensive in that it accounts for the lack of stem strengthening in exceptional forms, such as Krvaíte in the Rgveda. The implication is that the former procedure fails to account for the form, which, if Pāini's knowledge of texts were to be established based upon the consideration of individual traits, would imply the absurdity that Pāini, as interpreted by Rāmacandra et al. did not know the Rgveda. On the contrary, however, the procedure of Rāmacandra et al. can employ another rule of indeterminate variation: 3.1.85 vyatyayo bahulam. This procedure, which provides a systematic explanation of the present subjunctive generally and requires a rule of indeterminate variation only to account for exceptional forms, is preferable to leaving the account of stem strengthening in the present subjunctive generally to a rule of indeterminate variatio Since both procedures rely on rules of indeterminate variation to account for the Rgvedic form, however, it is impossible to establish either Pāini's knowledge or ignorance of the text on the basis of his account of the subjunctive. The controversy demonstrates that the depth and variety of the Indian grammatical tradition must be taken into account in determining which rules describe which linguistic facts and that it is inadequate to consider individual traits. A comprehensive approach is required.