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Space charge has been a general concern related with the reliability and the life-time of HVDC components. In this present work, the space charge profiles in oil-impregnated pressboards are investigated by the means of the pulsed electroacoustic (PEA) technique under AC voltage with 50 Hz at the room temperature. It has been observed that the ageing status of the mineral oil and the presence of the...
In the framework of developing defect-based life models (i.e. the life model of partial discharge-induced damage growth from a micro-void in polymer matrix), ageing tests were performed on PE layered specimens with artificial cavities under constant gas pressure and constant gas volume conditions, respectively. Time behavior of the discharge repetition rate and amplitude were recorded and compared...
Nanotechnologies are now inevitable regardless of the scope. In electrical engineering, especially in the context of "major" power systems, insulating materials of tomorrow are in the field of nanotechnologies. These new materials are commonly called "nanodielectrics". Having conducted numerous studies on the intrinsic electrical properties of nanomaterials, we propose in this...
HTV SIR has been widely used as the outer insulation of composite insulators, which mainly depends on the unique hydrophobicity of HTV SIR. In this paper, the influence of corona intensity on the hydrophobicity of HTV SIR was investigated. The HTV SIR samples were aged under five levels of voltage. The hydrophobicity loss and recovery were evaluated by static contact angle. Experiments results show...
Apparent mobility obtained from space charge decay measurement has been recently used as an ageing marker to assess degradation of the insulation materials. The apparent mobility of charge carriers becomes slower after experiencing electrical ageing. In this paper, we have measured space charge decay in polymeric insulation material using the pulsed electroacoustic technique and studied apparent mobility...
DC polarization and depolarization current (PDC) measurements are commonly used in the field in order to assess the quality of stator winding insulating systems of large synchronous rotating machines. Results from the measurement of polarization/depolarization currents on modern epoxy mica bars in various conditions are presented in this paper. The measurements were conducted for DC voltages ranging...
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