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The stator motor windings of low voltage rotating electrical machines are usually insulated by organic enamel. When the motors are supplied by power electronic converters, the stator insulation system is subjected to different voltage waveforms such as PWM. Due to reflection phenomena, overvoltage can be associated to pulsed waveforms and partial discharge (PD) activity can incept leading to the insulating...
The stator motor windings of low voltage rotating electrical machines are usually insulated by organic enamel. When the motors are supplied by power electronic converters, the stator insulation system is subjected to pulsed voltage waveform and a fast degradation of the insulating system could occur. In fact, it is possible that partial discharge (PD) activity incepts leading to the deterioration...
In this work thermoplastic polymeric blends based on Low Density Polyethylene (LDPE) and Ethylene Vinyl Acetate (EVA) have been studied. The blends have been prepared by twin screw compounding. In order to obtain different nanocomposite materials, montmorillonite and silica fillers have been considered. These two fillers are characterised by different aspect ratios: the first having a lamellar structure...
The insulation of power supply cables is increasingly performed by non-polar polymers. These materials, mainly polyolefins, combine low density and low cost of production. Among them, cross-linked polyethylene (XLPE) is up to date the best choice for an effective high voltage insulation. The aim of this work is to investigate the possibility to find out a new materials for electrical insulations that...
In this work thermoplastic polymeric blends based on low density polyethylene (LDPE) and ethylene vinyl acetate (EVA) have been investigated. The blends have been obtained mixing together portions of 80% of LDPE and 20% of EVA adding montmorillonite and silica as fillers to get different nanocomposite materials with different nanofillers amounts: chosen percentage were 3% and 7% by weight. The aim...
In this work thermoplastic polymeric blends have been investigated. Such blends are based on low density polyethylene mixed in 80∶20 (wt. %/wt. %) ratio with ethylene vinyl acetate. The nanocomposites has been obtained by adding montmorillonite and silica as fillers. The aim is to identify a new class of insulating materials for medium voltage equipment that could substitute the conventional ones...
This work investigates thermoplastic polymeric blends based on low density polyethylene and ethylene vinyl acetate mixed together in 80:20 weight ratio. These blends have been mixed with montmorillonite and silica as fillers to obtain nanocomposites with different nanofiller amounts: percentage of 3% and 7% by weight have been chosen. The aim is to identify a new class of insulating materials for...
This study focuses on blends with thermoplastic polymers matrices. The nanocomposites blends based on polyolefins could represents a new class of insulating materials with low environmental impact and good electrical performances. The materials object of this study have been prepared by adding different kinds and percentage of nanofillers as montmorillonite and silica to a thermoplastic polymeric...
The adoption of switching electronic converters for squirrel cage motor drives can lead to some critical issues during the normal operation. The early failure of the stator winding insulation is one of the most investigated problems. The cost of motor failure is measured by interruption of plant output as well as extent of repair or replacement. The Surge Test is one of the most important tests for...
Stator motor windings of low voltage rotating electrical machines are usually insulated by organic enamel. If during the normal operation partial discharges incept, degradation phenomena and in particular erosion, due to partial discharges, could take place leading the insulating system to breakdown conditions. In this research activity, conventional and nanocomposite enamels have been analyzed: suitable...
In these last years, different research studies constantly investigated the possibility to find a new class of materials in the field of medium/high voltage insulation. Nowadays, the conventional materials that are commonly used in this field of interest are non-recyclable. In this research activity, the electrical behavior of new recyclable nanostructured materials is investigated in order to study...
Electrical machines and in particular electrical motors used in industry applications are usually coupled with inverter drives in order to better control both the motor torque and speed. Due to the presence of these inverter drives, the stator motor windings are subjected to severe voltage waveforms. When the electrical motors having stator windings insulated by means of type I random wire wound are...
The following study evidences the effects of surface partial discharges aging on thin polymeric films in specific ambient conditions. The study has been performed on syndiotactic polypropylene and its nanocomposites. The specimens have been prepared by adding two different nanofillers to the pure polymer: montmorillonite and sepiolite, which are both silicate clays. In order to obtain a good dispersion...
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