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High voltage endurance is a fundamental characteristic of dielectrics. Ideally, the structure of dielectric, electrode design and type of employed electric field has no effect on internal breakdown endurance. On the other hand, experimentally estimated breakdown strengths are quite different under high voltage for the material given. This paper demonstrates space charge dynamics utilizing PEA (pulse electro-acoustic) system under high dc electric voltages to investigate the dependence of varying XLPE thickness on dielectric breakdown. As XLPE is employed for insulation of HVDC cables so it is mandatory to examine the space charge effects under high dc fields for varying insulation thickness. Generally, the influence of space charge leading to breakdown at high stresses is not considered for various bulk insulation thicknesses. However, we demonstrate the long time space charge profiles under high dc electric stresses for various thicknesses ranging from 0.07mm to 0.2mm. We examined that the time dependent internal field and space charge exhibit decreasing pattern with increasing thickness up to 0.1mm and then increasing pattern up to 0.2mm. Space charge measurements under high dc applied electric fields also depict a correspondence with short time dc breakdown test results. This observed phenomenon could find its importance in designing XLPE (material) insulation for HVDC transmission systems.

Power transformers are the most essential components of electrical power transmission and distribution networks. During the course of their operation, transformers are subjected to huge electrical and thermal stresses due to which insulation oil inside the transformer is highly degraded. The degradation of insulation oil leads to catastrophic transformer failure which further leads to power system network failure. Hence proper inspection and regular examination of transformer insulation oil is required for smooth and reliable operation of power system. In this research work, insulation oil samples from in-service transformers were taken and analyzed and the results were compared with same grade fresh mineral oil. Absorption spectroscopy techniques e.g. Fourier Transform Infrared Spectroscopy (FTIR) and UV-Visible Spectroscopy were adopted to analyze the insulation oil degradation. The outcome of absorption of aged transformer oil is so significant that absorption increased by observable margin over a wide range of wavelengths. Chemical characterization results highlight that huge amounts of impurities are added to the insulation oil that tend to highly degrade the oil and decrease useful service life of transformer. Hence a proper inspection of the most important part of transformer i.e. insulation oil is required on regular basis.

Polyhedral Oligomeric Silsesquioxane (POSS), a nanometric hybrid molecule, is being paid great attention in the field of polymeric micro and nanodielectrics, providing strong dispersion and dissolution power in solid and liquid dielectric materials which overcomes the sedimentation and agglomeration issues in nanocomposite insulation materials. This work presents the effect of temperature on electrical properties of Octa-isobutyl POSS (Oib-POSS) mineral based nanofluids prepared with two different concentrations 0.1 and 0.15 wt. % and the results are compared with fresh mineral oil. Dielectric properties that include relative permittivity, dissipation factor and volume resistivity along with the AC breakdown voltage are analyzed within a temperature range of 0-80°C in agreement with the IEC standards. Finally, 2-parameter Weibull analysis is performed over the AC breakdown voltage to validate the consistency of breakdown results. It is found that the POSS nanofluids show improved AC breakdown strength and dielectric properties e.g. relative permittivity, dissipation factor and volume resistivity compared with virgin mineral oil in entire temperature range. The results also show that the increase of POSS concentration not only improve the dielectric properties but also enhance the AC breakdown strength of mineral oil.

Insulating liquids have been applied to electrical insulation of transformers, circuit breakers and switch gears and have been investigated in different ways to enhance their performance. Dielectric liquids have been used for the transformer insulation and cooling applications since more than a century. Dielectric breakdown tests and the events and processes that affect the breakdown of the transformer insulation have been studied since last 40-50 years. Transformer oil can give a thorough picture of the internal transformer conditions. The fault diagnosis can also be done by investigating the transformer oil. For this reason, oil samples from a transformer that is out of service due to the internal faults are taken and tested to realize the reason behind the faults. Gas Chromatography Mass Spectrometry (GCMS) was employed to investigate the oil condition of the power transformer. GC-MS results show that high molecular weight substances in faulty oil are more than fresh oil. The results are compared with that of the fresh mineral oil supplied by the same manufacturer and presented in detail.

Vegetable insulating oils have different chemical compositions as compared to mineral oils, hence, dissolved gas characteristics under thermal and electrical faults have differences, thus fault diagnostic methods based on Dissolved gas analysis (DGA) used for mineral oil-filled transformers cannot be used to investigate vegetable oil-filled transformers. This paper presents experimental results of dissolved gases in the camellia insulating oil under typical thermal and electrical faults in transformers. The thermal fault simulation experiments include low temperature, medium temperature and high temperature, and the electrical fault simulation experiments include partial, breakdown and arc discharges. Experimental results show that except CO and CO 2 , H 2 and C 2 H 6 were main characteristic gases under thermal faults, the percentage contents of H 2 decreases while CH 4 , C 2 H 4 and C 2 H 6 increases with the temperature increase. In addition, H 2 and CH 4 were main characteristic gases under partial discharge faults, C 2 H 2 was the main characteristic gas under breakdown faults, and C 2 H 2 and C 2 H 4 were main characteristic gases under arc discharge faults. Characteristic parameters were extracted based on DGA, and fault diagnostic methods of camellia insulating oil-filled transformer were proposed, including graphic diagnostic method and none code diagnostic method. Results showed that faults could be effectively analyzed by triangle and pentagon diagnostic methods as well as none code diagnostic method. H 2 , C 2 H 4 , C 2 H 2 &H 2 , CH 4 , C 2 H 6 Triangle method and none code diagnostic method are better fault diagnostic methods for camellia insulating oil.

Vegetable insulating oils are gaining importance worldwide to be used in power transformers as an alternative to petroleum based mineral oils because of their biodegradable nature and higher fire points than conventional mineral oils. However, these oils (whether natural or synthetic esters) easily absorb moisture and hence tend to affect the dielectric and physiochemical properties of insulation oils. This paper presents the effect of moisture absorbed by commonly used rapeseed oil on its AC breakdown voltage. A mathematical relationship was developed between breakdown voltage and percentage moisture absorbed to access the values of BDV at any moisture level and this relationship holds good for any moisture content in the oil. Moreover, effect of suspended water molecules on breakdown voltage was simulated using COMSOL Multiphysics. Empirical relationship developed was tested and verified and can be used to find out the BDV of these oils as the percentage moisture increases.

The proliferation of giant hypermarkets propelled the demand of indoor positioning and navigation system for better customers' shopping experience. A customer that moves around a massive shopping area, for example 500,000-square-foot needs route guidance to search for the desired items and its location. The retailer on other hand wants to send real-time messages based on the customer's current location in the market. This paper addresses aforementioned problem and presents an intelligent solution for route problem for customer. Raw floor map of supermarket under consideration has been manually transformed into graph for combinatorial optimization. To meet the desired objective, Hungarian's and A∗ Search algorithms have been used in a cascaded manner to facilitate customer in two ways: (1) Chronological sequencing of items list will be suggested to customer based on the distance between current customer location and the location of item of his interest (2) Customer can also view the suggested single shortest path connecting every location of item of his shopping list based on A∗ findings. Once the proposed intelligent system navigation service is deployed on customer's smartphone, he or she can send or share item list with system to receive traces of desired location within premises. Results show that Hungarian Algorithm will assign optimal ordering for items to be purchased. Similarly A∗ search results in minimal iterations showing less time consumption and less number of nodes showing least memory requirement compared to Breadth first whilst searching for shortest route.

Transmission lines with high voltage generate a distributive capacitive current which have negative impact on differential current protection during faulty conditions. In order to remove the harmful and negative effects of distributed capacitive current on differential current protection, a novel scheme based on Bergeron's model is proposed in this article. Differential criterion is built with the same amount of currents that is computed from both ends to the set point. Implementation of the differential current protection under low sampling frequency proved that the criterion is correct for practical execution. The calculation of distributed current at the set point has been achieved using a unique procedure of cubic spline data interpolation point at each sampling interval under low sampling frequency. PSCAD simulation results in frequency domain show that this novel scheme for differential current protection is not affected by harmful effects of distributed capacitive current as compared to traditional differential current protection. Moreover, novel scheme has certain advantages such as high sensitivity, fast action speed and high reliability.

This study is aimed at presenting and developing a standard procedure for design of controlled technology of a high-performance three-phase AC-DC boost pulse width modulation converter. The system consists of the three-phase boost converter (universal bridge) controlled by a decoupled controller. The developed boost converter is used due to its features of two directional power conversion and operation at unity power factor. To control the DC output voltage, voltage oriented control technique with the decoupled controller has been used. MATLAB/SIMULINK is used to simulate the complete system. The output DC voltage, active and reactive power are obtained. The comparison results show that the new model is a more promising candidate in high-performance converters, which can be used in many different power electronic converter application.

Acrylonitrile Butadiene Styrene (ABS) is a thermo plastic material which is widely used for making bodies of countless electrical and medical appliances. It is low cost amorphous thermoplastic which belongs to poly styrene class of thermoplastics. It has very high tensile strength and almost unbreakable. It is a beneficial encapsulating and insulating material which is usually employed for indoor insulation and encapsulation purposes. A very little literature is reported on its performance when used in outdoor environment. In present work, ABS was molded into 11kV distribution class insulator and aged under several mechanical and electrical stresses in severe environmental conditions simulating outdoor environment according to IEC 1109 5000h aging standards. The aim of this study is to investigate the scope of using ABS for making outdoor insulators since it is a low cost material. Results show that this study is particularly useful for the researchers worldwide.

Recognizing emotional states is becoming a majorpart of a user's context for wearable computing applications. The system should be able to acquire a user's emotional states by using physiological sensors. We want to develop a personal emotional states recognition system that is practical, reliable, and can be used for health-care related applications. We propose to use the eHealth platform [1] which is a ready-made, light weight, small and easy to use device for recognizing a few emotional states like 'Sad', Dislike', 'Joy', 'Stress', 'Normal', 'No-Idea', 'Positive' and Negative' using decision tree (J48)and IBK classifiers. In this paper, we present an approach tobuild a system that exhibits this property and provides evidence based on data for 8 emotional states collected from 24 different subjects. Our results indicate that the system has an accuracy rate of approximately 97%.In our work, we used three physiological sensors (i.e. 'BloodVolume Pulse', 'Galvanic Skin Response' and 'SkinTemperature') in order to recognize emotional states (i.e.stress, joy/happy, sad, normal/neutral, dislike, no-idea, positive and negative).