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Stator windings of low voltage electrical motors are usually insulated by means of organic enamels. If motors are used in particular industrial plants or in nuclear applications, the enamel adopted to insulate the motor stator windings may be exposed to very intense gamma photonic irradiation fields. In this research activity, attention has been focused on the potential influence of gamma irradiation...
In this work the partial discharge (PD) patterns acquired during electrical aging tests performed on twisted pair specimens prepared by winding wires having conventional or nanostructured enamel insulation are compared. The conventional enamel is polyamide imide, while the nanostructured enamel is a polyamide-silica nanocomposite. The tests have been performed applying sinusoidal voltage at different...
This work concerns the comparison between the behaviour of winding wires insulated by a conventional organic enamel or by a nanocomposite enamel, when subjected to the action of surface partial discharges. Some aging tests were carried out applying a 1500 Hz sinusoidal voltage with different amplitudes. The outcome was summarized through lifetime plots. During the tests, partial discharges (PD) patterns...
Flat-conductors made by high temperature superconducting filaments can be electrically insulated by a host of different materials. After selecting the best performing system, an electrical characterisation stage has been implemented through dielectric breakdown tests in air and in liquid nitrogen (LN2) and through ageing in LN2, at atmospheric pressure
A set of surface discharge ageing procedures, space charge observations and dielectric strength measurements has been implemented on a type of insulating nanofilled epoxy-resin (nanostructured by compatibilised synthetic layered silicates) and on its non-filled base resin. Promising improvements in the electrical behaviour of the nanofilled epoxy, particularly as concerns surface discharge endurance,...
IEC/TC15 is preparing a new edition of Publication 112 concerning a method for determining the comparative tracking index (CTI) of solid insulating materials under moist conditions; the Electrical Engineering Dept., University of Genoa, has performed a set of tests on this subject. A short description of the aims, of the procedure and of the apparatus used for the tests reported in IEC Publ. 112 is...
The large number of applications of epoxy resins in the electrical industry originates an increasing interest in the behavior of these materials under endurance tests. In particular, several authors have studied_the action of partial discharges on these dielectrics1–5, which, in practice, are often subjected to this kind of stress. In the present paper, the first results of a research program on the...
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