It is well known that the breakdown voltage of an insulating liquid increases nonlinearly with increasing gap between the electrodes. Under nonuniform field DC conditions, two breakdown voltages are determined depending on the electrode polarity. Using point-plane geometries, with gaps of 5 mm or larger, it is found that typical transformer oils have higher breakdown voltages when the point is negative than when it is positive. Perfluorinated polyethers have been found to produce opposite results when using average gap sizes of 5 to 10 mm. To elucidate this situation a study of the effect of gap size on breakdown voltage has been undertaken. The results show that for the polyethers at larger gaps the sequence is reversed. These observations are explained in terms of the respective streamer developments in these liquids and the relative stability of their negative ions. The implications of these observations are discussed in some detail.
The effect of the electrode gap on the breakdown process in liquid dielectrics / E. O., Forster; H., Yamashita; MAZZETTI DI PIETRALATA, Carlo; Pompili, Massimo; L., Caroli; S., Patrissi. - STAMPA. - (1993), pp. 383-389. (Intervento presentato al convegno IEEE 11th International Conference on Conduction and Breakdown in Dielectric Liquids tenutosi a Baden-Dattwil, Svizzera nel 19-23 Luglio 1993) [10.1109/ICDL.1993.593972].
The effect of the electrode gap on the breakdown process in liquid dielectrics
MAZZETTI DI PIETRALATA, Carlo;POMPILI, Massimo;
1993
Abstract
It is well known that the breakdown voltage of an insulating liquid increases nonlinearly with increasing gap between the electrodes. Under nonuniform field DC conditions, two breakdown voltages are determined depending on the electrode polarity. Using point-plane geometries, with gaps of 5 mm or larger, it is found that typical transformer oils have higher breakdown voltages when the point is negative than when it is positive. Perfluorinated polyethers have been found to produce opposite results when using average gap sizes of 5 to 10 mm. To elucidate this situation a study of the effect of gap size on breakdown voltage has been undertaken. The results show that for the polyethers at larger gaps the sequence is reversed. These observations are explained in terms of the respective streamer developments in these liquids and the relative stability of their negative ions. The implications of these observations are discussed in some detail.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
