Wear-out and breakdown of polymers used as insulating materials are closely related to the dissipation electrostatic energy in space charge regions. A fraction this is radiated off by electroluminescence which can be considered a pre-breakdown warning provides probe investigate mechanisms leading structural degradation. Electroluminescence emission from two aromatic polyesters studied - poly(ethylene terephthalate) 2,6-naphthalate). We excitation processes luminescent centres, nature...

Electroluminescence detected in many different polymers under uniform 50 Hz ac and dc fields exhibits a threshold-like character, i.e. the light emission increases supralinearly with applied voltage above critical value called threshold. The significance of this threshold is not straightforward. It could be true physical corresponding to onset luminescence excitation as opposed sensitivity-limited without specific significance. This paper discusses issue on basis electroluminescence analysis...

Numerous parameters (environmental conditions, material and equipments design) affect the ageing (and consequently lifetime) of Electrical Insulation System (EIS) motors supplied by static converters. In order to find a modeling lifetime such materials, accelerated tests have be considered. The problem is that if we consider all relevant parameters, these become costly take lot time. Consequently topic this study use statistical method called: `Design Experiments' (DoE) obtain only...

The electroluminescence (EL) of insulating polymers is a subject great interest because it gives insight into aging and breakdown processes. While most the studies performed on polyolefins are under divergent field configurations, uniform used more more. However, convincing interpretation emission spectrum has not been given up to now, some discrepancies have appeared between spectra recorded fields. Wavelength-resolved EL carried out metalized polymeric films biased different ac dc voltage...

Electroluminescence associated with ac voltage aging of polyolefins has been reported under divergent field configuration. Neither the mechanism excitation nor nature luminescent centers are well understood in these polymers. Homegeneous experiments desirable since they easier to run and more light can be collected, thereby allowing spectral analysis made. We describe a suitable experimental configuration for electroluminescence detection from polyethylene polypropylene films submitted...

The dielectric and mechanical properties of standard (PEI), nanoscale-filled microscale-filled varnishes are detailed analyzed in this communication. Fumed silica (10 nm 400 nm) have been tested as a filler. A particular attention has paid to partial discharge inception voltage, lifetime under pulse voltage bonding strength which crucial for varnish be used rotating machines fed by inverters.

The resistance to partial discharges of pure, microfilled and nanofilled Polyetherimide varnish for low voltage motors fed by inverters is presented. Micro nano-sized Silica particles (1.5 % wt) are used as fillers. Experimental results lifetime versus temperature (-55 180°C), frequency (5 15 kHz) level the applied square (+/- 1 kV +/- 3 kV) clearly demonstrate that nanofillers more efficient than microfillers. polyetherimide found be up thirty times higher standard one. Crucial properties a...

This study aims to evaluate the optical losses of photovoltaic modules due Saharan dust deposition in Dakar, Senegal, West Africa. For this purpose, an air-dust-glass system is modeled simulate transmittance and reflectance. To do this, we have collected samples from Photo-Voltaic (PV) surface Dakar area (14°42'N latitude, 17°28'W longitude), Senegal. X-ray fluorescence reveals that silicon (Si), iron (Fe), calcium (Ca) potassium (K) mainly composed these samples. Then, refractive indices...

Nanocomposites obtained from polypropylene base materials and organophilic layered silicate as nanofiller might be a great source of innovation for the development advanced electrical devices. Previous investigations on dielectric properties such nanocomposites with either isotactic (iPP) or syndiotactic (sPP) matrix have shown that trapping are highly modified by presence nanofillers. A reduction space charge accumulation under DC stress has been shown. In this communication, we report...

Epoxy-SiC composites are commonly used as resistive field grading material for high voltage applications such corona protection of the end-windings stator windings large rotating machines. As a function grain size, concentration and composition, wide range electrical parameters can be reached epoxy-SiC composites. In this paper, optimized values characteristics field-grading (yielding lowest maximum field) were numerically calculated given geometry it was found that these optimum lay in...

Electroluminescence is excited in poly(ethylene 2,6-naphthalate) films submitted to a d.c. field. Kinetic and spectral analysis of the light emitted after field removal, so-called delayed luminescence, carried out order understand phosphorescence enhancement observed electroluminescence. It shown that emission can be interpreted terms tunnelling recombination deeply trapped electrons luminescent centres formed by ionized molecules. The due direct coupling between trapping state triplet molecule.

A large amount of parameters related to both operating conditions and material design affects the electrical ageing low voltage rotating machine insulation. Accelerated tests are usually undertaken in order develop a theory describe process determine lifetime model these materials. However, best our knowledge, there is no complete allowing prediction an insulation from accelerated tests, since many possible failure mechanisms various synergetic effects between them. Another problem with that...

Summarizes new results on the influence of some experimental parameters ac electroluminescence (EL) polymers used as insulating materials in electrical engineering. Electroluminescence under a uniform field is investigated low density polyethylene (PE) and naphthalate (PEN) films with semi-transparent electrodes both sides. Particular emphasis given to polyethylene. The dependence EL voltage frequency range 10/sup -2/ Hz +2/ help phase-resolved measurements. electrode/polymer contact by...

Low density polyethylene 500 µm thick samples have been submitted to a 15 MV m-1rms ac 50 Hz field. No charge accumulation in the has observed after few hours of polarization. This attributed recombination majority electrons and holes alternately injected each half cycle. To confirm this assumption, space sample by using dc electrical stress. Coupled measurements electroluminescence made under single double alternation Results shown that decrease installed at interfaces is partially due with...

The aim of this communication is to present the possibilities offered by luminescence techniques pointing out polymer surface transformations induced cold-plasma treatments. modifications can be monitored in situ inside plasma reactor. Measurements are carried as a function time, wavelength and temperature. Results obtained for polypropylene films treated with an atmospheric pressure glow discharge show that technique sensitive newly created chemical functions well cross linking carrier...

Results of DC conduction, breakdown strength and electroluminescence standard (PEI), nanoscale-fllled microscale-fllled varnishes are described analyzed in this communication. Silica (10nm 400nm) has been used as a filler to increase the lifetime such submitted partial discharge activity (varnish be rotating machines fed by inverters). Experimental results have shown that dielectric properties nanofilled varnish, which exhibits higher PD under stress, not highly affected fillers. On...

A new structure of integrated low-pass LC filter DC-DC power converter is proposed in this paper. This consists a circular planar coil enclosed between two ferrites substrates. Mn-Zn ferrite has been chosen because its high permeability and permittivity. In substrates act not only as magnetic core but also capacitor. order to reduce the conduction losses part used capacitor, particular topology using blocking layer proposed. modelling dielectric behaviour materials performed injected...

Wavelength-resolved electroluminescence and current measurements have been performed on polyethylene naphthalate thin films submitted to high direct fields (3.4 MV cm-1) for several days. The change in the shape of emission spectrum over time resembles that observed short-term experiments when field is increased. This behaviour provides basis a model which evolution attributed progressive charging material, through homopolar injection. net result an increase internal charge-free region where...

Silicate nanocomposites might be a great source of innovation for the development advanced electrical devices since filler introduction improves mechanical properties, thermal stability and some properties. In first part this paper we summarize results obtained by photoluminescence UV-visible absorption spectroscopy. The optical balance (absorption vs. diffusion) is discussed detailed emission spectra analysis provided. Grafting maleïc anhydride (MA) on PP chains induces formation broad band...

Nano-structured polypropylene (PP) materials are investigated resorting to electrical and luminescence measurements, by means of several experimental tools, in order evaluate their potentiality for application as insulation understand the mechanisms charge trapping relevant nano-structuration process. Both matrix compatibilization process filler content appear highly influential factors dielectric properties.

Dielectric spectroscopy and DC conduction current of Polyesterimide (PEI) -based nanocomposite filled with low concentration, 1.5wt.%, SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanoparticles about 10nm mean size have been performed analysis in comparison the unfilled PEI. The permittivity dielectric loss were found lower than those neat PEI respectively, particularly at high temperature frequencies. A distinct additional...

One commonly used strategy to enhance polymers specific properties such as the resistance partial discharges erosion is incorporation into polymeric matrix of inorganic micro or nanoparticles. This study focused on dielectric Low-Density Polyethylene (LDPE) filled with nano-sized Magnesium Oxide (MgO) particles compounded by thermo-mechanical process and one purposes was establish appropriate processing parameters in order reach desired properties. LDPE a reinforced MgO having nominal...

Changes in the optical and electrical properties of poly(ethylene 2,6-naphthalate) films aged under controlled UV irradiation are evaluated. Photoluminescence, conduction measurements electroluminescence have been carried out reference materials. The fluorescence yield significantly decreased materials, new bands that characteristic aging process appeared. also dramatically UV-aged materials so did external current DC field. This was confirmed by imaging a sample partly exposed to UVs. Some...

Results of EL emission in flat-sheet samples polymeric insulation (polyethylene), subjected to a uniform field, from two laboratories, are compared. The technique has been employed detect space charge injection, trapping and recombination centers the material. voltage varied over range often found practice, frequencies used cover part spectrum electrical electronic apparatus. aim this collaborative project is enhance understanding aging mechanisms dielectrics service, determine threshold...

A recent technique, using to potentially replace the conventional impregnating one in low voltage electric motors, has been studied this communication. The technique that uses both primary and secondary insulations; i.e.: enamel varnish, compared which only component, self-bonding wires. Self-bonding wires polymerization is very quick of technique. Environmental impact dielectric mechanical properties these two techniques have estimated compared. goal estimate if not a better environmental...