Power Research

L. Zevgolas ¹, Y. Cheng ², M. G. Danikas ³, R. Sarathi ⁴

Affiliations
1 Department of Electrical and Computer Engineering,Democritus University of Thrace, Xanthi, GR
2 State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an Jiaotong University, Xi’an, P. R, CN
3 Department of Electrical and Computer Engineering, Democritus University of Thrace, Xanthi, GR
4 Department of Electrical Engineering, Indian Institue of Technology Madras, Chennai, IN

Abstract

In this paper nanocomposite samples of epoxy resin and TiO2 nanoparticles and microparticles were investigated with water droplets on their surface. Samples with 1 wt% nanoparticles, 1 wt% nanoparticles with 3 wt% microparticles, 3 wt% nanoparticles and also 3 wt% nanoparticles with 3 wt% microparticles were investigated. A uniform electric field was applied and the behaviour of the water droplets was observed. Parameters that were studied were the water conductivity, the droplet volume, number of droplets and the droplet positioning w.r.t. the electrodes. All above mentioned parameters influence the flashover voltage of the samples. It is to be noted that – at least in some cases – the water droplet positioning w.r.t. the electrodes was more important in determining the flashover voltage than the droplet volume. The results indicate that the addition of microparticles in a nanocomposite does not necessarily improve the flashover voltage behaviour.

Keywords

Flashover voltage, surface discharges, nanocomposites, uniform electric field, water droplet, water conductivity

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V. Sathiesh Kumar ¹, Nilesh J. Vasa ², R. Sarathi ³

Affiliations
1 Department of Electronics Engineering, Madras Institute of Technology, Anna University, Chennai- 600044, IN
2 Department of Engineering Design, Indian Institute of Technology Madras, Chennai- 600036, IN
3 Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai- 600036, IN

Abstract

A methodical experimentation and mathematical modeling is carried out to study the influence of salt deposit on wind turbine blade material (Glass Fiber Reinforced Plastics/GFRP) during lightning discharges. Electrical discharge measurements combined with optical emission spectroscopy technique and electrostatics is utilized to understand the dynamics of surface discharge and the level of damage on GFRP material. COMSOL simulation studies shows that the electric field intensity on the surface of the polluted GFRP gets enhanced when compared to that of virgin GFRP, irrespective of the applied voltage profile and polarity. Flashover voltage, discharge current and optical emission spectroscopy measurements indicates that the deterioration of GFRP material is severe when there is an adhesion of salt deposit. It is also observed that the damage induced on GFRP material is severe for winter lightning (switching impulse voltage of 250/2500 μs) compared to that of summer lightning (lightning impulse voltage of 1.2/50 μs) due to a longer front and tail period of the pulse.

Keywords

Wind blade, pollution measurement, flashover voltage, lightning impulse, switching impulse, temporal and spatial measurements

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Srijith Kanakambaran ¹, T. Obulesu ¹, R. Sarathi ¹, Balaji Srinivasan ¹

Affiliations
1 Department of Electrical Engineering, Indian Institute of Technology Madras Chennai - 600 036, IN

Abstract

We present a Fiber Bragg Grating (FBG) based scheme for sensing corona discharges in a power transformer. The corona-induced acoustic emissions detected using the FBG sensor pasted in a test cell is found to be correlated to the signals detected by HFCT sensor. A detailed spectral analysis of the detected signals is presented and the influence of electrode gap on the acoustic spectrum is investigated.

Keywords

Corona, partial discharge, power transformer, fiber bragg gratings 1.0

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Gynendra Kumar ¹, Archana Sharma ¹, R. Sarathi ²

Affiliations
1 Homi Bhabha National Institute, Accelerator and Pulse Power Division , Mumbai-400085, IN
2 Department of Electrical engineering, Indian Institite of technology, Madras, Chennai, IN

Abstract

In this review paper after various reported data from 2000 to 2016 published in IEEE and science direct, are analyzed and discussed to explore the feasibility of pulsed power application in cell biology. Targeting inhabitation of cancer/tumor proliferation treatment as main fields, some other associated topics e.g. effect on plasma membrane, apoptosis induction etc. are investigated in vitro and in vivo, it summarizes, HOW the nano second Pulse Electric Field (nsPEF) affects eukaryotic cells that are healthy as well as that are affected by tumor/cancer i.e. unhealthy. Term electroporation came into the picture which stands for opening pore in cell membrane using pulse of electricity, to introduce DNA or chromosomes into bacteria or other cells. Width of the applied electrical pulse used also caused different cellular effects, pulses longer than 100μs, in electroporation, delivers DNA, protein, small drugs and fluorescent indicators across the plasma membrane and causes moderate levels of Phosphatidyl Serine (PS) translocation at the Plasma Membrane, while shorter pulses less than 1μs are central to intracellular effects such as apoptosis induction (programmed cell death) and higher levels of Phosphatidyl Serine (PS) translocation. In addition, nsPEFs acts as cellular stress that introduces translational suppression. Ultra-short electricity i.e. nsPEFs can reach intra cellular component directly without membrane destruction causes apoptosis induction (programmed cell death). Also it has been found that direct current produced by applied voltage induces specific biological healing of tissues near the electrodes, also the effect of current is same as in ionizing radiation of tumor therapy. Chemotherapeutic drugs along with nsPEF reduces dose of both types of treatments. Also, nsPEFs causes transient activation of signaling pathways involving Mitogen-Activated Protein Kinases (MAPKs). Now days, nsPEFs are recognized as unique tool in life science.

Keywords

Nano second pulsed electric field, apoptosis induction, electroporation

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N. Aparna ¹, N. J. Vasa ¹, R. Sarathi ²

Affiliations
1 Department of Engineering Design, Indian Institute of Technology Madras Chennai-600036, IN
2 Department of Electrical Engineering, Indian Institute of Technology Madras Chennai-600036, IN

Abstract

Surface flashover phenomena under lightening impulse voltage of positive and negative polarity on thermally aged Oil Impregnated Pressboard (OIP) material used in transformer is studied. OIP material with surface deposited Cu at different concentrations are also used for comparison. Total energy deposited on the OIP material and the magnitude of discharge current increased with ageing duration. The decay characteristics concerning optical emission from the surface flashover matched with the temporal decay of discharge current. The study also revealed some of the pre-breakdown phenomena before the main flashover breakdown. Optical Emission Spectroscopy (OES) revealed signature of diffused Cu and S in aged OIP material. Higher emission intensity for Cu was observed for higher aged OIP material, indicating larger possibility of degradation. OIP material collected from a failed transformer also showed optical emission lines matching with Cu emission, indicating possibility of employing the OES technique in contaminant detection. The temperature of the plasma during the surface flashover was also estimated.

Keywords

Surface flashover, lightening impulse, oil impregnated pressboard, discharge current, prebreakdown, optical emission spectroscopy

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Palash Mishra ¹, G. Parvathy ², R. Sarathi ¹

Affiliations
1 Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai- 600 036, IN
2 Easwari Engineering College, Ramapuram, Chennai-600 089, IN

Abstract

Corona activity can cause reduction in hydrophobicity of silicone rubber insulating material. Leakage current (LC) measured during water droplet discharge was analyzed through Recurrence Plot (RP) analysis. The RP obtained for the leakage current formed due to water droplet discharges under AC and DC voltages are different. Recurrent Quantification Analysis (RQA) is used to quantify the results of RP plots to classify the discharges formed under AC and DC voltages. Multi Resolution Signal Decomposition (MRSD) technique is adopted to understand the frequency contents present in the leakage current at different instants.

Keywords

Corona, leakage current, recurrenceplot, recurrence quantification, Multiresolution signal decomposition

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Prem Ranjan ¹, Yusuke Nakayama ², L. Santhosh Kumar ³, R. Jayaganthan ⁴, H. Suematsu ², R. Sarathi ¹

Affiliations
1 Department of Electrical Engineering, IIT Madras, Chennai, 600036, IN
2 Extreme Energy-Density Research Institute, Nagaoka University of Technology, Nagaoka 940-2188, JP
3 Department of Aerospace Engineering, IIT Madras, Chennai, 600036, IN
4 Department of Engineering Design, IIT Madras, Chennai, 600036, IN

Abstract

Iron oxide (Fe₂O₃) nanoparticles were generated in a single step by wire explosion process (WEP). The influence of energy deposited to the exploding conductor and the ambient pressure on phase, size and shape of the particle were analysed. Oxygen is used as medium during wire explosion process to obtain iron oxide. The characteristics of the particles were analysed through WAXD and TEM. The thermodynamic aspects of nanoparticle formation by wire explosion process are detailed.

Keywords

Nanoparticle; Wire Explosion; Iron Oxide; Born-Haber cycle; Nucleation rate

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P. Nagachandrika ¹, K. Sridharan ¹, R. Sarathi ¹

Affiliations
1 Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai- 600 036, IN

Abstract

An attempt has been made to understand the surface discharge resistance of epoxy molybdenum disulphide nanocomposite material under AC and DC voltages. To characterize the material, surface charge accumulation studies and basic dielectric properties of the material viz., permittivity and tan(𝛿) of the material were carried out. Also the level of degradation of insulating material characterized through contact angle measurement and by surface roughness measurements. The results of the study conclude that 0.5 wt% of epoxy nanocomposites showed high discharge resistance.

Keywords

Nanocomposite, Surface Discharge, MoS2, surface roughness

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