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Dr. Shakeel Akram
Sichuan University, China

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Research Keywords & Expertise

0 Partial discharges
0 Dielectric materials
0 space charge
0 Electrical insulation
0 Nanotechology

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space charge
Dielectric materials
Electrical insulation
breakdown strength
high voltage insulation materials

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Short Biography

Shakeel Akram (M’17) was born in Pakistan in 1987, He received his Master degree in electrical engineering from Chongqing University, Chongqing, China in 2012 and two Ph.D. degrees in Electrical Engineering from Southwest Jiaotong University Chengdu China in 2018 and Institut d’Electronique et des Systèmes (IES), University of Montpellier, Montpellier, France in 2020. Currently, he is working as research associate in Sichuan University, Chengdu, China and University of Montpellier, Montpellier, France. His major research area includes electrical characterizations and simulation of high voltage insulating materials, deposition of thin films, HVDC cables, PWM inverter fed motors and polymer-based nanocomposites, nanodielectrics. In high voltage testing his specialty is to develop space charge diagnostic tools (PEA, TSM, PVDF sensor) and pulse power PD testing techniques (UHF).

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Communication
Published: 25 August 2021 in Polymers
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Room temperature vulcanized (RTV) silicone rubber filled with aluminum trihydrate (ATH) is substantially engaged in electrical outdoor insulation applications. The pristine silicone rubber is highly combustible. ATH filled silicone rubber offers excellent electrical insulation butlacks in providing adequate flame retardancy. This short communication reports the novel results on improved flame retardancy of pristine and ATH filled silicone rubber whilst retaining the electrical insulation properties to a great extent. Results suggest that the presence of only one percent of graphene nanoplatelets with ATH sharply reduces the heat release rate and rate of smoke release. A minor reduction in dielectric breakdown strength and volume resistivity is noticed. Furthermore, permittivity and dielectric loss at power frequency suggest that a marginal 1% concentration of nanoplatelet with ATH is an excellent approach to fabricate flame retardant silicone rubber with an acceptable electrical insulation level.

ACS Style

Muhammad Tariq Nazir; Arslan Khalid; Imrana Kabir; Cheng Wang; Juan-Carlos Baena; Shakeel Akram; Muhammad Shoaib Bhutta; Ghulam Yasin; Bao Toan Phung; Guan Heng Yeoh. Flame Retardancy and Excellent Electrical Insulation Performance of RTV Silicone Rubber. Polymers 2021, 13, 2854 .

AMA Style

Muhammad Tariq Nazir, Arslan Khalid, Imrana Kabir, Cheng Wang, Juan-Carlos Baena, Shakeel Akram, Muhammad Shoaib Bhutta, Ghulam Yasin, Bao Toan Phung, Guan Heng Yeoh. Flame Retardancy and Excellent Electrical Insulation Performance of RTV Silicone Rubber. Polymers. 2021; 13 (17):2854.

Chicago/Turabian Style

Muhammad Tariq Nazir; Arslan Khalid; Imrana Kabir; Cheng Wang; Juan-Carlos Baena; Shakeel Akram; Muhammad Shoaib Bhutta; Ghulam Yasin; Bao Toan Phung; Guan Heng Yeoh. 2021. "Flame Retardancy and Excellent Electrical Insulation Performance of RTV Silicone Rubber." Polymers 13, no. 17: 2854.

Journal article
Published: 06 August 2021 in Coatings
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Cost-effective, clean, highly transparent, and flexible as well as a coatable packaging material is envisioned to solve or at least mitigate quality preservation issues of organic materials, originating from moisture interaction under ambient conditions. Liquid phase processing of packaging coatings using nano-clay and polyvinyl alcohol (PVOH) has been developed and reported. Detailed analysis of the developed coating revealed moisture permeability of 2.8 × 10−2 g·cm/m2·day at 40 °C and 85% relative humidity (RH), which is in close accordance with Bharadwaj’s theoretical permeability model. Moreover, the developed coatings are not only more than 90% transparent, when exposed to white light, but also exhibit excellent flexibility and even after going through 10,000 bending cycles maintained the same blocking effect against moisture.

ACS Style

Ali Chandio; Iftikhar Channa; Muhammad Rizwan; Shakeel Akram; Muhammad Javed; Sajid Siyal; Muhammad Saleem; Muhammad Makhdoom; Tayyaba Ashfaq; Safia Khan; Shahid Hussain; Munirah Albaqami; Reham Alotabi. Polyvinyl Alcohol and Nano-Clay Based Solution Processed Packaging Coatings. Coatings 2021, 11, 942 .

AMA Style

Ali Chandio, Iftikhar Channa, Muhammad Rizwan, Shakeel Akram, Muhammad Javed, Sajid Siyal, Muhammad Saleem, Muhammad Makhdoom, Tayyaba Ashfaq, Safia Khan, Shahid Hussain, Munirah Albaqami, Reham Alotabi. Polyvinyl Alcohol and Nano-Clay Based Solution Processed Packaging Coatings. Coatings. 2021; 11 (8):942.

Chicago/Turabian Style

Ali Chandio; Iftikhar Channa; Muhammad Rizwan; Shakeel Akram; Muhammad Javed; Sajid Siyal; Muhammad Saleem; Muhammad Makhdoom; Tayyaba Ashfaq; Safia Khan; Shahid Hussain; Munirah Albaqami; Reham Alotabi. 2021. "Polyvinyl Alcohol and Nano-Clay Based Solution Processed Packaging Coatings." Coatings 11, no. 8: 942.

Journal article
Published: 23 May 2021 in Micromachines
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This numerical study aims to interpret the impact of non-linear thermal radiation on magnetohydrodynamic (MHD) Darcy-Forchheimer Casson-Water/Glycerine nanofluid flow due to a rotating disk. Both the single walled, as well as multi walled, Carbon nanotubes (CNT) are invoked. The nanomaterial, thus formulated, is assumed to be more conductive as compared to the simple fluid. The properties of effective carbon nanotubes are specified to tackle the onward governing equations. The boundary layer formulations are considered. The base fluid is assumed to be non-Newtonian. The numerical analysis is carried out by invoking the numerical Runge Kutta 45 (RK45) method based on the shooting technique. The outcomes have been plotted graphically for the three major profiles, namely, the radial velocity profile, the tangential velocity profile, and temperature profile. For skin friction and Nusselt number, the numerical data are plotted graphically. Major outcomes indicate that the enhanced Forchheimer number results in a decline in radial velocity. Higher the porosity parameter, the stronger the resistance offered by the medium to the fluid flow and consequent result is seen as a decline in velocity. The Forchheimer number, permeability parameter, and porosity parameter decrease the tangential velocity field. The convective boundary results in enhancement of temperature facing the disk surface as compared to the ambient part. Skin-friction for larger values of Forchheimer number is found to be increasing. Sufficient literature is provided in the introduction part of the manuscript to justify the novelty of the present work. The research greatly impacts in industrial applications of the nanofluids, especially in geophysical and geothermal systems, storage devices, aerospace engineering, and many others.

ACS Style

Anum Shafiq; Ghulam Rasool; Hammad Alotaibi; Hassan Aljohani; Abderrahim Wakif; İlyas Khan; Shakeel Akram. Thermally Enhanced Darcy-Forchheimer Casson-Water/Glycerine Rotating Nanofluid Flow with Uniform Magnetic Field. Micromachines 2021, 12, 605 .

AMA Style

Anum Shafiq, Ghulam Rasool, Hammad Alotaibi, Hassan Aljohani, Abderrahim Wakif, İlyas Khan, Shakeel Akram. Thermally Enhanced Darcy-Forchheimer Casson-Water/Glycerine Rotating Nanofluid Flow with Uniform Magnetic Field. Micromachines. 2021; 12 (6):605.

Chicago/Turabian Style

Anum Shafiq; Ghulam Rasool; Hammad Alotaibi; Hassan Aljohani; Abderrahim Wakif; İlyas Khan; Shakeel Akram. 2021. "Thermally Enhanced Darcy-Forchheimer Casson-Water/Glycerine Rotating Nanofluid Flow with Uniform Magnetic Field." Micromachines 12, no. 6: 605.

Book chapter
Published: 05 May 2021 in Polyimide for Electronic and Electrical Engineering Applications
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Polymer nanocomposite-based dielectric materials are playing a vital role in the area of electrical insulation research and developments. The nanoparticle dispersion and interface region are the crucial parts of these developments. This chapter begins with the description of physical properties and their derived nanoparticles of polyimide (PI) films. Then, the detailed synthesis process of PI/nanocomposite multilayer film and its optimization is discussed in this chapter. Several factors in the synthesis process, which can influence the quality of the film, are discussed. After synthesis, the dielectric properties such as space charge were measured, and the results are compared with single and multilayer PI/nanocomposite films. Simulations and modeling help to shed light on the experimental results and create an understanding of polymer nanocomposite properties. Therefore, the PI/nanocomposite multilayer 3D model based on boundary conditions obtained from SEM/TEM images of synthesized samples was also constructed and simulated in COMSOL multiphysics software. The nanoparticle agglomeration and the impact of nanoparticle dispersion on the electrical properties of the material are described in detail in this model. The results demonstrate that the nanoparticle dispersion is improved by using a thin layer of PI/nanocomposite on PI film. As a result, fewer space charges and low electric fields are observed in multilayer films.

ACS Style

Shakeel Akram; Jérôme Castellon; Serge Agnel; Jean-Pierre Habas. Synthesis Process Optimization of Polyimide Nanocomposite Multilayer Films, Their Dielectric Properties, and Modeling. Polyimide for Electronic and Electrical Engineering Applications 2021, 1 .

AMA Style

Shakeel Akram, Jérôme Castellon, Serge Agnel, Jean-Pierre Habas. Synthesis Process Optimization of Polyimide Nanocomposite Multilayer Films, Their Dielectric Properties, and Modeling. Polyimide for Electronic and Electrical Engineering Applications. 2021; ():1.

Chicago/Turabian Style

Shakeel Akram; Jérôme Castellon; Serge Agnel; Jean-Pierre Habas. 2021. "Synthesis Process Optimization of Polyimide Nanocomposite Multilayer Films, Their Dielectric Properties, and Modeling." Polyimide for Electronic and Electrical Engineering Applications , no. : 1.

Journal article
Published: 21 February 2021 in Polymers
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The steady-state electrical conduction current for single and multilayer polyimide (PI) nanocomposite films was observed at the low and high electric field for different temperatures. Experimental data were fitted to conduction models to investigate the dominant conduction mechanism in these films. In most films, space charge limited current (SCLC) and Poole–Frenkel current displayed dominant conduction. At a high electric field, the ohmic conduction was replaced by current–voltage dependency. Higher conduction current was observed for nanocomposite films at a lower temperature, but it declined at a higher temperature. PI nanocomposite multilayer films showed a huge reduction in the conduction current at higher electric fields and temperatures. The conclusions derived in this study would provide the empirical basis and early breakdown phenomenon explanation when performing dielectric strength and partial discharge measurements of PI-based nanocomposite insulation systems of electric motors.

ACS Style

Muhammad Bhutta; Shakeel Akram; Pengfei Meng; Jerome Castellon; Serge Agnel; Hui Li; Yecai Guo; Ghulam Rasool; Shahid Hussain; Muhammad Nazir. Steady-State Conduction Current Performance for Multilayer Polyimide/SiO2 Films. Polymers 2021, 13, 640 .

AMA Style

Muhammad Bhutta, Shakeel Akram, Pengfei Meng, Jerome Castellon, Serge Agnel, Hui Li, Yecai Guo, Ghulam Rasool, Shahid Hussain, Muhammad Nazir. Steady-State Conduction Current Performance for Multilayer Polyimide/SiO2 Films. Polymers. 2021; 13 (4):640.

Chicago/Turabian Style

Muhammad Bhutta; Shakeel Akram; Pengfei Meng; Jerome Castellon; Serge Agnel; Hui Li; Yecai Guo; Ghulam Rasool; Shahid Hussain; Muhammad Nazir. 2021. "Steady-State Conduction Current Performance for Multilayer Polyimide/SiO2 Films." Polymers 13, no. 4: 640.

Review
Published: 03 December 2020 in Coatings
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Surface charge accumulation in the spacer modifies local electric fields, which restricts the industrialization of high voltage direct current (HVDC) gas-insulated transmission lines (GILs). In this paper, the state of art in gas/solid interface charging physics and models, covering areas of charge measurement techniques, charge transport mechanisms, charge related DC surface flashover models, and charge control methods, is reviewed and discussed. Key issues that should be considered in future studies are summarized and proposed. The purpose of this work is to provide a brief update on the most important and latest progress in this research area, and to educate readers as to the current state of the gas-solid interface charging phenomenon, which has seen great progress in the past few years.

ACS Style

Shakeel Akram; Jérôme Castellon; Serge Agnel. Progress in Gas/Solid Interface Charging Phenomena. Coatings 2020, 10, 1184 .

AMA Style

Shakeel Akram, Jérôme Castellon, Serge Agnel. Progress in Gas/Solid Interface Charging Phenomena. Coatings. 2020; 10 (12):1184.

Chicago/Turabian Style

Shakeel Akram; Jérôme Castellon; Serge Agnel. 2020. "Progress in Gas/Solid Interface Charging Phenomena." Coatings 10, no. 12: 1184.

Journal article
Published: 23 October 2020 in IEEE Access
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The partial discharge (PD) in inverter-fed motors generated from high frequency and short rise time impulsive voltage are more complex than traditional sinusoidal voltage operated motors due to the noise initiated from fast switching power electronics devices. Available PD sensors and related technology for DC and sinusoidal voltage cannot be used at repetitive impulsive voltage conditions. This work aims to report the design of antenna with optimized geometry and satisfied parameters to detect PD for impulsive voltage. The antenna is verified and the influence of both impulse voltage parameters and test configuration on PD features are discussed. The envelope detection technique after the filter in the frequency domain was proposed to reduce the complexity and cost of PD test hardware under impulsive voltages with fast rise times. The frequency domain energy of PD from motor insulation is mainly distributed in the range of 0.6-1.8 GHz. By increasing the amplitude and frequency of input impulsive voltage, the range of PD energy spectrum is enlarged to (1.5-1.8 GHz) and by decreasing input amplitude the PD signal strength decays abruptly. Moreover, the high-frequency distribution of PD energy attenuates more severely with the distance and the electromagnetic energy of PD decays nonlinearly with the increase of propagation distance. Therefore, under the premise of satisfying the safety test, selecting the test distance below 15 cm can ensure that the test results have a high signal-to-noise ratio and signal integrity. The experience reported in this study could provide suggestions for off-line PD measurements for inverter-fed motor insulation evaluations for manufacturers.

ACS Style

Peng Wang; Ma Shijin; Shakeel Akram; Kai Zhou; Yidong Chen; Muhammad Tariq Nazir. Design of Archimedes Spiral Antenna to Optimize for Partial Discharge Detection of Inverter Fed Motor Insulation. IEEE Access 2020, 8, 1 -1.

AMA Style

Peng Wang, Ma Shijin, Shakeel Akram, Kai Zhou, Yidong Chen, Muhammad Tariq Nazir. Design of Archimedes Spiral Antenna to Optimize for Partial Discharge Detection of Inverter Fed Motor Insulation. IEEE Access. 2020; 8 ():1-1.

Chicago/Turabian Style

Peng Wang; Ma Shijin; Shakeel Akram; Kai Zhou; Yidong Chen; Muhammad Tariq Nazir. 2020. "Design of Archimedes Spiral Antenna to Optimize for Partial Discharge Detection of Inverter Fed Motor Insulation." IEEE Access 8, no. : 1-1.

Journal article
Published: 27 September 2020 in Polymers
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The application of wide band-gap power electronic devices brings more challenges to insulating packaging technology. Knowing the influence of applied voltage parameters on insulation performance is helpful to evaluate the insulation condition of electric power equipment. In this paper, the effect of repetitive square wave voltage duty cycle on the growth characteristics of electrical trees in epoxy resin was studied. The experimental results show that the square wave voltage duty cycle has a significant influence on treeing features. The electrical tree proportion initiation has shown a decreasing trend, and the shape of the electrical tree changes from pine-like to branch-like by increasing the duty cycles. The length and damaged area of electrical tree increased with the increase in the duty cycle up to 10% and then decrease by increasing the duty cycle higher than 30%. It indicates that a low duty cycle will enhance the electron injection and accumulate space charges and thus accelerate electrical tree development. Under short duty cycles, the electric field due to the shielding effect near the needle tip suppresses the electrical tree growth, which results in treeing growth stagnation. The obtained results are helpful to keep these parameters in mind during the design of epoxy-based insulation such high-voltage rotating machines and power electronic device packaging.

ACS Style

Peng Wang; Suxin Hui; Shakeel Akram; Kai Zhou; Muhammad Tariq Nazir; Yiwen Chen; Han Dong; Muhammad Sufyan Javed; Inzamam Ul Haq. Influence of Repetitive Square Voltage Duty Cycle on the Electrical Tree Characteristics of Epoxy Resin. Polymers 2020, 12, 2215 .

AMA Style

Peng Wang, Suxin Hui, Shakeel Akram, Kai Zhou, Muhammad Tariq Nazir, Yiwen Chen, Han Dong, Muhammad Sufyan Javed, Inzamam Ul Haq. Influence of Repetitive Square Voltage Duty Cycle on the Electrical Tree Characteristics of Epoxy Resin. Polymers. 2020; 12 (10):2215.

Chicago/Turabian Style

Peng Wang; Suxin Hui; Shakeel Akram; Kai Zhou; Muhammad Tariq Nazir; Yiwen Chen; Han Dong; Muhammad Sufyan Javed; Inzamam Ul Haq. 2020. "Influence of Repetitive Square Voltage Duty Cycle on the Electrical Tree Characteristics of Epoxy Resin." Polymers 12, no. 10: 2215.

Article
Published: 15 August 2020 in Journal of Polymer Science
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The preparation of polyimide (PI)/nanocomposite films and their thickness are a complex process with some ambiguous variables that are involved in the synthesis process. Therefore, it is crucial to understand those variables and reveal the chemistry behind them. Several methods have been probed until an optimal synthesis process was found. A detailed synthesis process optimization is described in this article to understand all variables, which can influence the molecular weight of polyamic acide (PAA) solution, the thickness of films, and nanoparticles dispersion. The spin coating technique was used to control the thickness of single and multilayer PI/nanocomposite films, which reveals that the thickness of the casted PI film depends on several factors, such as the viscosity, molecular weight of the PAA solution, and the spin speed of spin coater. Factors, which can influence the molecular weight of PAA solution, are discussed in detail. After completing the synthesis process, the single and multilayer PI nanocomposite films are characterized experimentally. The results reveal that using a thin layer of nanocomposite on PI film in the form of a multilayer structure improves the nanoparticles dispersion and thereafter its dielectric properties.

ACS Style

Shakeel Akram; Jérôme Castellon; Serge Agnel; Kai Zhou; Jean‐Pierre Habas; Muhammad Tariq Nazir. Multilayer polyimide nanocomposite films synthesis process optimization impact on nanoparticles dispersion and their dielectric performance. Journal of Polymer Science 2020, 138, 1 .

AMA Style

Shakeel Akram, Jérôme Castellon, Serge Agnel, Kai Zhou, Jean‐Pierre Habas, Muhammad Tariq Nazir. Multilayer polyimide nanocomposite films synthesis process optimization impact on nanoparticles dispersion and their dielectric performance. Journal of Polymer Science. 2020; 138 (4):1.

Chicago/Turabian Style

Shakeel Akram; Jérôme Castellon; Serge Agnel; Kai Zhou; Jean‐Pierre Habas; Muhammad Tariq Nazir. 2020. "Multilayer polyimide nanocomposite films synthesis process optimization impact on nanoparticles dispersion and their dielectric performance." Journal of Polymer Science 138, no. 4: 1.

Journal article
Published: 26 July 2020 in Engineering Failure Analysis
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The urgent need for electric vehicles is the leading research to safer operation of electric motors on high frequency impulsive voltages. For low voltage electric vehicles partial discharge (PD) inception voltage tests under impulse voltage waveforms are desired. However, measuring PD using repetitive impulse waveforms is critical in selecting generators with appropriate parameters to increase PD detection sensitivity. Here, we report on PD characteristics for such kind of voltage waveforms, demonstrated with the high frequency and thermal impact on different types of motor insulation models. The increasing frequency of impulsive voltages tends to result in PD activities with low magnitude and short delay times. In this case, some PD pulses are missed because the PD and disturbance pulses produced by power electronic devices will likely overlap. Therefore, these parameters are carefully considered to evaluate the insulation performance of EV motors.

ACS Style

Shakeel Akram; Peng Wang; Muhammad Tariq Nazir; Kai Zhou; M. Shoaib Bhutta; Haider Hussain. Impact of impulse voltage frequency on the partial discharge characteristic of electric vehicles motor insulation. Engineering Failure Analysis 2020, 116, 104767 .

AMA Style

Shakeel Akram, Peng Wang, Muhammad Tariq Nazir, Kai Zhou, M. Shoaib Bhutta, Haider Hussain. Impact of impulse voltage frequency on the partial discharge characteristic of electric vehicles motor insulation. Engineering Failure Analysis. 2020; 116 ():104767.

Chicago/Turabian Style

Shakeel Akram; Peng Wang; Muhammad Tariq Nazir; Kai Zhou; M. Shoaib Bhutta; Haider Hussain. 2020. "Impact of impulse voltage frequency on the partial discharge characteristic of electric vehicles motor insulation." Engineering Failure Analysis 116, no. : 104767.

Journal article
Published: 05 March 2020 in Polymers
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Ethylene propylene diene monomer (EPDM) is broadly employed as an insulating material for high voltage applications. Surface discharge-induced thermal depolymerization and carbon tracking adversely affect its performance. This work reports the electrical field modeling, carbon tracking lifetime, infrared thermal distribution, and leakage current development on EPDM-based insulation with the addition of nano-BN (boron nitride) contents. Melt mixing and compression molding techniques were used for the fabrication of nanocomposites. An electrical tracking resistance test was carried out as per IEC-60587. Simulation results show that contamination significantly distorted the electrical field distribution and induced dry band arcing. Experimental results indicate that electric field stress was noticed significantly higher at the intersection of insulation and edges of the area of contamination. Moreover, the field substantially intensified with the increasing voltage levels. Experimental results show improved carbonized tracking lifetime with the addition of nano-BN contents. Furthermore, surface temperature was reduced in the critical contamination flow path. The third harmonic component in the leakage current declined with the increase of the nano-BN contents. It is concluded that addition of nano-BN imparts a better tracking failure time, and this is attributed to better thermal conductivity and thermal stability, as well as an improved shielding effect to electrical discharges on the surface of nanocomposite insulators.

ACS Style

Muhammad Tariq Nazir; Faizan Tahir Butt; Bao Toan Phung; Guan Heng Yeoh; Ghulam Yasin; Shakeel Akram; Muhammad Shoaib Bhutta; Shahid Hussain; Tuan Anh Nguyen. Simulation and Experimental Investigation on Carbonized Tracking Failure of EPDM/BN-Based Electrical Insulation. Polymers 2020, 12, 582 .

AMA Style

Muhammad Tariq Nazir, Faizan Tahir Butt, Bao Toan Phung, Guan Heng Yeoh, Ghulam Yasin, Shakeel Akram, Muhammad Shoaib Bhutta, Shahid Hussain, Tuan Anh Nguyen. Simulation and Experimental Investigation on Carbonized Tracking Failure of EPDM/BN-Based Electrical Insulation. Polymers. 2020; 12 (3):582.

Chicago/Turabian Style

Muhammad Tariq Nazir; Faizan Tahir Butt; Bao Toan Phung; Guan Heng Yeoh; Ghulam Yasin; Shakeel Akram; Muhammad Shoaib Bhutta; Shahid Hussain; Tuan Anh Nguyen. 2020. "Simulation and Experimental Investigation on Carbonized Tracking Failure of EPDM/BN-Based Electrical Insulation." Polymers 12, no. 3: 582.

Accepted manuscript
Published: 27 November 2019 in Materials Research Express
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Insulation structure of inverter fed motors especially used in high speed railways undergo continuous stresses of short pulses, making it difficult to maintain the insulation strength. To enhance its mechanical and dielectric properties, core shell of another dielectric material and deposition of nano layer structure dielectric materials are being utilized in modern research. There is great demand to explore electrical properties of such layered structure possessing thin dielectric layers of nanometric dimensions particles. The electrical performance of layer structure (nano-Polyimide-nano) consisting of two different types of nano particles (Al2O3 and SiO2) are investigated and results are compared with each other as well as with single layer structure. The structural interface and physical properties of dispersion of nano additive layers on polyimide are studied by microscopic analysis and other features such as weight loss, dielectric spectroscopy, and electrical and mechanical breakdown strength are also analyzed. Results showed that the tri-layer structure with SiO2 additive have higher electrical breakdown strength compared with other types, 40% increase compared with single layer nano films, 30% enhancement compared with tri-layer Al2O3-PI-Al2O3 films. In addition, notable variations in results are observed at higher temperature. The current research study on the basis of type, size and structure of sample will help manufacturers especially in the field of motor industry to select nano reinforced PI film according to industrial application.

ACS Style

Shakeel Akram; Muhammad Tariq Nazir; Jerome Castellon; Serge Agnel; Kai Zhou; M. Shoaib Bhutta; Zhou Kai. Preparation and distinguish dielectric properties of multi-layer nanoparticles-based polyimide films. Materials Research Express 2019, 6, 125092 .

AMA Style

Shakeel Akram, Muhammad Tariq Nazir, Jerome Castellon, Serge Agnel, Kai Zhou, M. Shoaib Bhutta, Zhou Kai. Preparation and distinguish dielectric properties of multi-layer nanoparticles-based polyimide films. Materials Research Express. 2019; 6 (12):125092.

Chicago/Turabian Style

Shakeel Akram; Muhammad Tariq Nazir; Jerome Castellon; Serge Agnel; Kai Zhou; M. Shoaib Bhutta; Zhou Kai. 2019. "Preparation and distinguish dielectric properties of multi-layer nanoparticles-based polyimide films." Materials Research Express 6, no. 12: 125092.

Conference paper
Published: 01 October 2019 in 2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)
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ACS Style

Shakeel Akram; Jerome Castellon; Serge Agnel; Jean-Pierre Habas; Zhou Kai; Muhammad Tariq Nazir. Impact of Nanocomposite Thin Layer on Nanoparticles Dispersion and their Dielectric Properties. 2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP) 2019, 1 .

AMA Style

Shakeel Akram, Jerome Castellon, Serge Agnel, Jean-Pierre Habas, Zhou Kai, Muhammad Tariq Nazir. Impact of Nanocomposite Thin Layer on Nanoparticles Dispersion and their Dielectric Properties. 2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP). 2019; ():1.

Chicago/Turabian Style

Shakeel Akram; Jerome Castellon; Serge Agnel; Jean-Pierre Habas; Zhou Kai; Muhammad Tariq Nazir. 2019. "Impact of Nanocomposite Thin Layer on Nanoparticles Dispersion and their Dielectric Properties." 2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP) , no. : 1.

Article
Published: 01 July 2019 in Journal of Materials Science: Materials in Electronics
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Ethylene propylene diene monomer (EPDM) is a polymer widely used for insulation in high voltage outdoor insulators and cables. It is well accepted that appropriate addition of micron particles to form a composite can enhance its insulation performance. This work reports improvement on the dielectric breakdown strength, tracking failure time, mechanical properties and volume resistivity of EPDM composites co-filled with boron nitride (BN) micron and nano–particles. Test specimens were fabricated by melt-blending and hot press techniques. AC breakdown tests were performed as per IEC60243-1 Standard. The tracking test was performed following IEC 60587 Standard and volume resistivity measurement as per ASTM D257. Experimental results show improvement in electrical properties with increasing particle loading up to a certain dosage but enhancement in the mechanical properties is observed up to 30 wt% particles addition. The co-filled composite exhibits considerably higher dielectric breakdown strength (89.24 kV/mm) and volume resistivity (~ 5.0 × 1015 Ω cm) relative to Micro-20 wt%. The tracking failure time of the co-filled is much improved due to excellent resistance against dry band arcing and thermal accumulation in the discharge region. Moreover, co-filled composites show improvement in mechanical properties as compared to the micron–filled counterparts. The improved thermal conductivity, better thermal stability and overall higher surface area of the particles are possible factors which impart better performance to the co-filled composites.

ACS Style

M. Tariq Nazir; B. T. Phung; Shengtao Li; Shakeel Akram; M. Ali Mehmood; Guan Yeoh; Shahid Hussain. Effect of micro-nano additives on breakdown, surface tracking and mechanical performance of ethylene propylene diene monomer for high voltage insulation. Journal of Materials Science: Materials in Electronics 2019, 30, 14061 -14071.

AMA Style

M. Tariq Nazir, B. T. Phung, Shengtao Li, Shakeel Akram, M. Ali Mehmood, Guan Yeoh, Shahid Hussain. Effect of micro-nano additives on breakdown, surface tracking and mechanical performance of ethylene propylene diene monomer for high voltage insulation. Journal of Materials Science: Materials in Electronics. 2019; 30 (15):14061-14071.

Chicago/Turabian Style

M. Tariq Nazir; B. T. Phung; Shengtao Li; Shakeel Akram; M. Ali Mehmood; Guan Yeoh; Shahid Hussain. 2019. "Effect of micro-nano additives on breakdown, surface tracking and mechanical performance of ethylene propylene diene monomer for high voltage insulation." Journal of Materials Science: Materials in Electronics 30, no. 15: 14061-14071.

Conference paper
Published: 01 October 2018 in 2018 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)
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The work is performed to investigate the electrical properties of multi-structure polyimide (PI) films, such as space charge phenomenon that can help us to improve the performance of these insulating films. Under high electric field and temperature, some changes at the atomic scale can lead to the space charge accumulation. Thermal Step Method (TSM) is a sensitive and handy technique to observe such changes in dielectric materials. It is used to observe the ability of these multi-structure films to accumulate/release space charges after thermoelectric poling, close to the practical applications. In-Situ polymerization method is used to prepare PI films. After curing, some films were fluorinated and put under electric field for different temperatures. Thermal Step (TS) current is measured using current amplifier and then space charge density and electric field can be calculated mathematically. From results, we found that the TS current for fluorinated films is quite different from non-fluorinated films. Coating of fluorination on both sides act as barrier and provide resistance to space charge injection from the electrodes. These coated-layers are discharge resistive and increase the charge dissipation rate to limit the space charge accumulation.

ACS Style

Shakeel Akram; Jerome Castellon; Serge Agnel; M. Zeeshan Khan. Space Charge Analysis of Multi-Structure Polyimide Films using TSM. 2018 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP) 2018, 34 -37.

AMA Style

Shakeel Akram, Jerome Castellon, Serge Agnel, M. Zeeshan Khan. Space Charge Analysis of Multi-Structure Polyimide Films using TSM. 2018 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP). 2018; ():34-37.

Chicago/Turabian Style

Shakeel Akram; Jerome Castellon; Serge Agnel; M. Zeeshan Khan. 2018. "Space Charge Analysis of Multi-Structure Polyimide Films using TSM." 2018 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP) , no. : 34-37.

Journal article
Published: 10 August 2018 in IEEE Transactions on Dielectrics and Electrical Insulation
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Measurements of space charge density and trap levels are informative ways to predict failure conditions of insulation materials. The charges are injected from electrodes and penetrate from surface towards deep inside of the insulation material. In order to resist the charge injection, trapping, migration and increase charge recombination, detrapping and extraction rate, layer (nanocomposite-PI-nanocomposite) sandwich structure samples are used. Two techniques Pulse Electro Acoustic (PEA) and Thermal Stimulated Current (TSC) are combined to characterize space charge behavior and trap levels. Lab-view based program is used to detect the charge density distribution and total charge decay, different peaks of current using TSC technique are used to get activation energy and trap level density. The effects of structural interface (single, double, triple layers) and types of nano (Al 2 O 3 , SiO 2 ) fillers are analyzed to influence charge accumulation polarity and trap levels. Trap levels are calculated using TSC data as well as total charge decay data. The trap values calculated from both data match each other. Al 2 O 3 -PI-Al 2 O 3 sandwich structure showed remarkable improvements to resist accumulation of space charge for longer time. Mostly charges are shallow traps with 1.126 eV trap level and recombination rate is higher. In double layer structure in which interface is made up of SiO 2 and Al 2 O 3 , deep trap level of 1.26 eV and higher trap density is observed. The charges decay is faster in three-layer structure than double and single layer structure. It is concluded that the interface formed with different type of nano and structure of insulation, both are an important parameter for manufacturing industry to suppress space charges accumulation and traps.

ACS Style

Shakeel Akram; Yan Yang; Xin Zhong; Shoaib Bhutta; Guangning Wu; Jerome Castellon; Kai Zhou. Influence of nano layer structure of polyimide film on space charge behavior and trap levels. IEEE Transactions on Dielectrics and Electrical Insulation 2018, 25, 1461 -1469.

AMA Style

Shakeel Akram, Yan Yang, Xin Zhong, Shoaib Bhutta, Guangning Wu, Jerome Castellon, Kai Zhou. Influence of nano layer structure of polyimide film on space charge behavior and trap levels. IEEE Transactions on Dielectrics and Electrical Insulation. 2018; 25 (4):1461-1469.

Chicago/Turabian Style

Shakeel Akram; Yan Yang; Xin Zhong; Shoaib Bhutta; Guangning Wu; Jerome Castellon; Kai Zhou. 2018. "Influence of nano layer structure of polyimide film on space charge behavior and trap levels." IEEE Transactions on Dielectrics and Electrical Insulation 25, no. 4: 1461-1469.

Journal article
Published: 01 December 2017 in IEEE Transactions on Dielectrics and Electrical Insulation
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Measurements of space charge density and trap levels are informative ways to predict failure conditions of insulation materials. The charges are injected from electrodes and penetrate from surface towards deep inside of the insulation material. In order to resist the charge injection, trapping, migration and increase charge recombination, de-trapping and extraction rate, layer (nanocomposite-PI-nanocomposite) sandwich structure samples are used. Two techniques Pulse Electro Acoustic (PEA) and Thermal Stimulated Current (TSC) are combined to characterize space charge behavior and trap levels. Lab-view based program is used to detect the charges density distribution and total charge decay, different peaks of current using TSC technique are used to get activation energy and trap level density. The effects of structural interface (single, double, three layers) and types of nano (Al 2 O 3 , SiO 2 ) fillers are analyzed to influence charge accumulation polarity and trap levels. Trap levels are calculated using TSC data as well as total charge decay data. The trap values calculated from both data match each other. Al 2 O 3 -PI-Al 2 O 3 sandwich structure showed remarkable improvements to resist accumulation of space charge for longer time. Mostly charges are shallow traps with 1.126eV trap level and recombination rate is higher. In double layer structure in which interface is made up of SiO 2 and Al 2 O 3 , deep trap level of 1.26 eV and higher trap density is observed. The charges decay is faster in three layer structure than double and single layer structure. It is concluded that the interface formed with different type of nano and structure of insulation, both are an important parameters for manufacturing industry to suppress space charges accumulation and traps.

ACS Style

Shakeel Akram; Yan Yang; Xin Zhong; Shoaib Bhutta; Guangning Wu; Jerome Castellon; Kai Zhou. Influence of nano layer interface on space charge behavior and trap levels using polyimide sandwich structure. IEEE Transactions on Dielectrics and Electrical Insulation 2017, 24, 3505 -3514.

AMA Style

Shakeel Akram, Yan Yang, Xin Zhong, Shoaib Bhutta, Guangning Wu, Jerome Castellon, Kai Zhou. Influence of nano layer interface on space charge behavior and trap levels using polyimide sandwich structure. IEEE Transactions on Dielectrics and Electrical Insulation. 2017; 24 (6):3505-3514.

Chicago/Turabian Style

Shakeel Akram; Yan Yang; Xin Zhong; Shoaib Bhutta; Guangning Wu; Jerome Castellon; Kai Zhou. 2017. "Influence of nano layer interface on space charge behavior and trap levels using polyimide sandwich structure." IEEE Transactions on Dielectrics and Electrical Insulation 24, no. 6: 3505-3514.

Journal article
Published: 01 December 2015 in IEEE Transactions on Dielectrics and Electrical Insulation
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Failure mechanism due to corona aging and characteristics of PD (partial discharge) on nano doped PI (polyimide) film are investigated under bipolar impulse voltage. Chemical characterization of material is analyzed through SEM (scanning electron microscope) and FTIR (Fourier transform infrared spectroscopy). The results show that failure of specimens is mainly caused by surface discharge which could be suppressed by the addition of nano particles. The Al 2 O 3 nano fillers improved the corona resistant property of PI film significantly. The corona resistant lifetime of PI/Al 2 O 3 sample is six times longer than that of pure PI. Furthermore, to know the frequency and rise time effect of surface discharge on specimens, mean discharge quantity of PD under impulse voltage is measured. Increase of pulse frequency leads to enhancement of PD activity, whereas increase of rise time, weakens PD activity. The discovered effects of profound significance will help on improving dielectric properties of nanocomposites towards various applications.

ACS Style

Shakeel Akram; Guoqiang Gao; Yang Liu; Jian Zhu; Guangning Wu. Degradation mechanism of A12O3 nano filled polyimide film due to surface discharge under square impulse voltage. IEEE Transactions on Dielectrics and Electrical Insulation 2015, 22, 3341 -3349.

AMA Style

Shakeel Akram, Guoqiang Gao, Yang Liu, Jian Zhu, Guangning Wu. Degradation mechanism of A12O3 nano filled polyimide film due to surface discharge under square impulse voltage. IEEE Transactions on Dielectrics and Electrical Insulation. 2015; 22 (6):3341-3349.

Chicago/Turabian Style

Shakeel Akram; Guoqiang Gao; Yang Liu; Jian Zhu; Guangning Wu. 2015. "Degradation mechanism of A12O3 nano filled polyimide film due to surface discharge under square impulse voltage." IEEE Transactions on Dielectrics and Electrical Insulation 22, no. 6: 3341-3349.

Journal article
Published: 01 September 2015 in Journal of Electrical Engineering & Technology
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Cavity and Interface effect of PI-Film on Charge Accumulation and PD Activity under Bipolar Pulse Voltage Partial discharge;Surface charge;Bipolar square pulse waveform;Polyimide film;Breakdown;Electric field distortion; With the continuous development in insulation of electrical equipment design, the reliability of the system has been enhanced. However, in the manufacturing process and during operation under continues stresses introduce local defects, such as voids between interfaces that can responsible to occurrence of partial discharge (PD), electric field distortion and accumulation of charges. These defects may lead to localize corrosion and material degradation of insulation system, and a serious threat to the equipment. A model of three layers of PI film with air gap is presented to understand the influence of interface and voids on exploitation conditions such as strong electrical field, PD activity and charge movement. The analytical analysis, and experimental results are good agreement and show that the lose contact between interfaces accumulate more residual charges and in consequences increase the electric field intensity and accelerates internal discharges. These residual charges are trapped charges, injected by the electrodes has often same polarity, so the electric field in cavities increases significantly and thus partial discharge inception voltage (PDIV) decreases. Contrary, number of PD discharge quantity increases due to interface. Interfacial polarization effect has opposite impact on electric field and PDIV as compare to void.

ACS Style

Shakeel Akram; Guangning Wu; Guoqiang Gao; Yang Liu. Cavity and Interface effect of PI-Film on Charge Accumulation and PD Activity under Bipolar Pulse Voltage. Journal of Electrical Engineering & Technology 2015, 10, 2089 -2098.

AMA Style

Shakeel Akram, Guangning Wu, Guoqiang Gao, Yang Liu. Cavity and Interface effect of PI-Film on Charge Accumulation and PD Activity under Bipolar Pulse Voltage. Journal of Electrical Engineering & Technology. 2015; 10 (5):2089-2098.

Chicago/Turabian Style

Shakeel Akram; Guangning Wu; Guoqiang Gao; Yang Liu. 2015. "Cavity and Interface effect of PI-Film on Charge Accumulation and PD Activity under Bipolar Pulse Voltage." Journal of Electrical Engineering & Technology 10, no. 5: 2089-2098.

Conference paper
Published: 01 August 2015 in 2015 IEEE Electrical Insulation Conference (EIC)
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Failure mechanisms and PD (partial discharge) characteristics on rigid polyimide film are revealed under bipolar pulse voltage. Mean discharge quantity of PD under square waveform is measured for pure polyimide (PI) and nano doped PI film. Results of Scanning Electron microscope (SEM) showed that surface discharge (corona) is main reason of PI insulation material failure and nano particles addition can suppress PD activity. Increase in frequency leads higher PD activity, while increase of rise time decrease PD activity. The results show that the traps during mobility and residual effect of space charges have larger influence on PD activity, and high surface conductivity of nano samples can reduce memory effect of charges and PD activity. The nano filler provides shielding layer to repel surface erosion and thermal conduction.

ACS Style

Shakeel Akram; Guangning Wu; Guoqiang Gao; Yang Liu. Effect of surface discharge on nano filled polyimide film under square voltage. 2015 IEEE Electrical Insulation Conference (EIC) 2015, 226 -229.

AMA Style

Shakeel Akram, Guangning Wu, Guoqiang Gao, Yang Liu. Effect of surface discharge on nano filled polyimide film under square voltage. 2015 IEEE Electrical Insulation Conference (EIC). 2015; ():226-229.

Chicago/Turabian Style

Shakeel Akram; Guangning Wu; Guoqiang Gao; Yang Liu. 2015. "Effect of surface discharge on nano filled polyimide film under square voltage." 2015 IEEE Electrical Insulation Conference (EIC) , no. : 226-229.