scholarly journals Simulation and Experimental Investigation on Carbonized Tracking Failure of EPDM/BN-Based Electrical Insulation

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 582 ◽  
Author(s):  
Muhammad Tariq Nazir ◽  
Faizan Tahir Butt ◽  
Bao Toan Phung ◽  
Guan Heng Yeoh ◽  
Ghulam Yasin ◽  
...  
Keyword(s):  
Leakage Current ◽  
Failure Time ◽  
Harmonic Component ◽  
Experimental Results ◽  
Shielding Effect ◽  
Surface Discharge ◽  
Melt Mixing ◽  
Electrical Field ◽  
Third Harmonic ◽  
Thermal Depolymerization

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.

Thermal Image and Leakage Current Diagnostic as a Tool for Testing and Condition Monitoring of ZnO Surge Arrester

2013 ◽  
Vol 64 (4) ◽  
Author(s):  
Novizon N. ◽  
Zulkurnain Abdul Malek ◽  
Nouruddeen Bashir ◽  
N. Asilah
Keyword(s):  
Leakage Current ◽  
Condition Monitoring ◽  
Thermal Imaging ◽  
Harmonic Component ◽  
Strong Relationship ◽  
Thermal Image ◽  
Aging Condition ◽  
Third Harmonic ◽  
Surge Arresters ◽  
Thermal Data

This paper presents a study proposing a method to assess the condition of metal-oxide surge arresters. Thermal data using thermal imaging as well as the leakage current third harmonic component were used as tools to investigate the surge arrester aging condition.  Artificial Neural Network was employed to classify surge arrester condition with the temperature profile, ambient temperature and humidity as inputs and third harmonic leakage current as target. The results indicated a strong relationship between the thermal profile and leakage current of the surge arrester. This finding suggests the viability of this method in condition monitoring of surge arrester.

Imaging Cracks in Bones Using Acoustic Nonlinearity: A Simulation Study

2011 ◽  
Vol 97 (5) ◽  
pp. 728-733
Author(s):  
Yang Liu ◽  
Xiasheng Guo ◽  
Zhao Da ◽  
Dong Zhang ◽  
Xiufen Gong
Keyword(s):  
Time Reversal ◽  
Three Dimensional ◽  
Harmonic Component ◽  
Ultrasonic Signal ◽  
Long Bone ◽  
Third Harmonic ◽  
Acoustic Nonlinearity ◽  
The Third ◽  
Nonlinear Approach ◽  
Radial Depth

This article proposes an acoustic nonlinear approach combined with the time reversal technique to image cracks in long bones. In this method, the scattered ultrasound generated from the crack is recorded, and the third harmonic nonlinear component of the ultrasonic signal is used to reconstruct an image of the crack by the time reversal process. Numerical simulations are performed to examine the validity of this approach. The fatigue long bone is modeled as a hollow cylinder with a crack of 1, 0.1, and 0.225 mm in axial, radial and circumferential directions respectively. A broadband 500 kHz ultrasonic signal is used as the exciting signal, and the extended three-dimensional Preisach-Mayergoyz model is used to describe the nonclassical nonlinear dynamics of the crack. Time reversal is carried out by using the filtered third harmonic component. The localization capability depends on the radial depth of the crack.

Analysis of error motions of axial locking-prevention hydrostatic spindle

2018 ◽  
Vol 233 (1) ◽  
pp. 3-17
Author(s):  
Penghai Zhang ◽  
Yaolong Chen
Keyword(s):  
Significant Influence ◽  
Harmonic Component ◽  
Necessary Condition ◽  
Third Harmonic ◽  
The Third ◽  
Fourth Harmonic ◽  
Radial Error ◽  
Tilt Error ◽  
Error Motion ◽  
Error Averaging

Hydrostatic spindles are widely used in precision optical grinder and lathe. Their high precision comes from the error averaging effect of oil film. The purpose of this paper is to give the quantitative analysis of the error averaging effect for a newly developed axial locking-prevention hydrostatic spindle. An approximate error motion model of the hydrostatic spindle is established to analyze the internal relationship between the geometric errors of the shaft and the error motions of the spindle including radial, tilt and axial error motions. The theoretical analysis shows that, the roundness errors of the two journals have a major impact on error motions while the coaxiality errors of two journals, the perpendicularity errors of front thrust plate and the coaxiality errors of the land of back thrust bearing, have no significant influences on error motions. The elliptical component of roundness errors of the two journals has significant influence on the axial error motion but no influence on the pure radial and tilt error motions, resulting into the fourth harmonic component of axial error motion. The trilobal component of roundness errors of the two journals has significant influence on the pure radial and tilt error motions but no influence on the axial error motion, resulting in the third harmonic component of pure radial and tilt error motions. The changes of recess pressures are not necessary condition for the error motions. Additionally, the experiment analysis shows that, the third harmonic component is the main part of the measured radial error motion and the third, fourth harmonic components are the main parts of the measured face error motion, which can be reasonably explained by the theory. The model proposed in this paper can be used to guide the precision design and optimization of hydrostatic spindle.

Partial Discharge Characterization based on Leakage Current Pulses Waveform for Contaminated Glass Insulator String

2016 ◽  
Vol 6 (2) ◽  
pp. 835
Author(s):  
N. A. Othman ◽  
M. A. M. Piah ◽  
Z. Adzis ◽  
Nasir A. Al-geelani
Keyword(s):  
Corona Discharge ◽  
Monitoring System ◽  
Leakage Current ◽  
Partial Discharge ◽  
Surface Discharge ◽  
Performance Tests ◽  
Current Pulses ◽  
Glass Insulator

This paper deals with the analysis of partial discharge (PD) occurrences based on leakage current (LC) pulses distribution under different level of contamination. In this work, laboratory based contamination performance tests are conducted on four units of glass insulator string stacked in I-position. Results show that PD can be characterized (according to their occurrence with respect to the AC supply) as follows: corona discharge occurring dominantly in lightly contaminated insulators, surface discharge occurring dominantly in medium contaminated insulators and finally internal discharge occurring dominantly in heavily contaminated insulators. The ability to distinguish the type of PDs from the LC waveform could be used to monitor and predict the condition of the insulator. The outcome can be incorporated in a conditioning monitoring system.

Electrical Characteristics of New LDD Poly-Si TFT with MIS-Alignment Tolerant Structure for AMLCDs

1997 ◽  
Vol 471 ◽  
Author(s):  
Byung-Hyuk Min ◽  
Jerzy Kanicki
Keyword(s):  
Leakage Current ◽  
Experimental Results ◽  
Electrical Characteristics ◽  
Current Ratio ◽  
Low Leakage ◽  
Kink Effect ◽  
Low Leakage Current ◽  
Dual Gate ◽  
Output Characteristics

ABSTRACTA new LDD poly-Si TFT structure having symmetrical electrical characteristics independent of the process induced mis-alignment is described in this paper. Based on the experimental results, we have established there is no difference between the forward and reverse characteristics and a low leakage current, comparable to a conventional LDD poly-Si TFT, has been maintained for this new poly-Si TFTs. The maximum ON/OFF current ratio of about 1×108 is obtained for the LDD length of 1.0 μm. In addition, the kink effect in the output characteristics is remarkably improved in the new TFTs in comparison to the conventional non-LDD single- or dual-gate TFTs.

THIRD-HARMONIC EMISSION IN MgB2 SUPERCONDUCTOR AT MICROWAVE FREQUENCIES

2003 ◽  
Vol 17 (04n06) ◽  
pp. 535-541 ◽  
Author(s):  
A. AGLIOLO GALLITTO ◽  
G. BONSIGNORE ◽  
M. LI VIGNI
Keyword(s):  
Magnetic Field ◽  
Static Magnetic Field ◽  
Power Level ◽  
Input Power ◽  
Experimental Results ◽  
Mgb2 Superconductor ◽  
Microwave Frequencies ◽  
Third Harmonic ◽  
Harmonic Emission ◽  
Harmonic Signals

We report a set of experimental results on microwave third-harmonic emission by MgB 2 superconductor. We have investigated third-harmonic signals as a function of temperature, input power level and intensity of the static magnetic field. We show that different mechanisms are responsible for third-harmonic emission at temperatures near T c and far below T c , similarly to what has been obtained in other high- T c superconductors.

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