scholarly journals Research on the Time-Domain Dielectric Response of Multiple Impulse Voltage Aging Oil-Film Dielectrics

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1948
Author(s):  
Chenmeng Zhang ◽  
Kailin Zhao ◽  
Shijun Xie ◽  
Can Hu ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Time Domain ◽  
Dielectric Response ◽  
Early Stage ◽  
Debye Model ◽  
Polarization Current ◽  
Depolarization Current ◽  
Oil Film ◽  
Impulse Voltage ◽  
The Time Domain ◽  
Film Dielectric

Power capacitors suffer multiple impulse voltages during their lifetime. With the multiple impulse voltage aging, the internal insulation, oil-film dielectric may deteriorate and even fail in the early stage, which is called accumulative effect. Hence, the time-domain dielectric response of oil-film dielectric with multiple impulse voltage aging is studied in this paper. At first, the procedure of the preparation of the tested samples were introduced. Secondly, an aging platform, impulse voltage generator was built to test the accumulative effect of capacitor under multiple impulse voltage. Then, a device was used to test the time-domain dielectric response (polarization depolarization current, PDC) of oil-film dielectric in different aging states. And finally, according to the PDC data, extended Debye model and characteristic parameters were obtained by matrix pencil algorithm identification. The results indicated that with the increase of impulse voltage times, the time-domain dielectric response of oil-film dielectric changed accordingly. The polarization current curve moved up gradually, the insulation resistance decreased when subjected to the repeated impulses. In frequency domain, the frequency spectrum of tan δ changed along with the impulse accumulation aging, especially at low frequency. At last, combined with the aging mechanism of oil-film dielectric under multiple impulse voltage, the test results were discussed.

scholarly journals Transformation Algorithm of Dielectric Response in Time-Frequency Domain

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Ji Liu ◽  
Daning Zhang ◽  
Xinlao Wei ◽  
Hamid Reza Karimi
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Dielectric Response ◽  
Low Frequency ◽  
Dissipation Factor ◽  
Depolarization Current ◽  
Ultralow Frequency ◽  
Time Frequency ◽  
Transformation Algorithm ◽  
The Time Domain

A transformation algorithm of dielectric response from time domain to frequency domain is presented. In order to shorten measuring time of low or ultralow frequency dielectric response characteristics, the transformation algorithm is used in this paper to transform the time domain relaxation current to frequency domain current for calculating the low frequency dielectric dissipation factor. In addition, it is shown from comparing the calculation results with actual test data that there is a coincidence for both results over a wide range of low frequencies. Meanwhile, the time domain test data of depolarization currents in dry and moist pressboards are converted into frequency domain results on the basis of the transformation. The frequency domain curves of complex capacitance and dielectric dissipation factor at the low frequency range are obtained. Test results of polarization and depolarization current (PDC) in pressboards are also given at the different voltage and polarization time. It is demonstrated from the experimental results that polarization and depolarization current are affected significantly by moisture contents of the test pressboards, and the transformation algorithm is effective in ultralow frequency of 10−3 Hz. Data analysis and interpretation of the test results conclude that analysis of time-frequency domain dielectric response can be used for assessing insulation system in power transformer.

Time Domain Response of Electrical Ceramics Micro to Megaseconds

1997 ◽  
Vol 500 ◽  
Author(s):  
F. A. Modine
Keyword(s):  
Electrical Properties ◽  
Power Law ◽  
Time Domain ◽  
Polarization Current ◽  
Electrical Measurements ◽  
Dispersive Transport ◽  
Electron Traps ◽  
Source Impedance ◽  
Wide Range ◽  
The Time Domain

ABSTRACTThe electrical properties of ceramics can be measured in either the time domain or in the frequency domain. But for electrically nonlinear ceramics such as varistors, time-domain measurements provide insights that are different and more relevant to material performance as well as being more physically incisive. This article focuses specifically on the electrical properties of ZnO varistors, but much of it is of relevance for other materials, in particular those materials with grain-boundary barriers and disordered ceramics or glasses. The interpretation of electrical measurements in the time domain is profoundly influenced by such practical matters as source impedance and waveform characteristics. Experimental results are presented for both high and low source impedance relative to that of a test varistor, and the difference in experimental difficulty and ease of interpretation is described. Time-domain measurements of capacitance and of the inductive response of varistors to large, fast electrical pulses are presented and their implications for varistor theory are given. Experimental evidence is given of short- and long-term memory in varistors. These memory phenomena are ascribed respectively to the life time of holes that become trapped in barriers and to polarization currents originating from deep electron traps. Polarization current measurements are presented for a wide range of time and temperature. The power-law time dependence and “universal” behavior of these currents is discussed. The exponent that describes the power law behavior is seen to change with temperature, and the change is interpreted as a double transition from diffusive to dispersive transport that originates with current from two different electron traps.

Research on the Equivalent Circuit Modeling of Oil-Paper Insulation of Transformer by Analyzing the Dielectric Spectra

2012 ◽  
Vol 260-261 ◽  
pp. 408-413
Author(s):  
Yong Qing Liu ◽  
Jin Ding Cai ◽  
Yan Xue Guo
Keyword(s):  
Equivalent Circuit ◽  
Time Domain ◽  
Equivalent Circuit Model ◽  
Debye Model ◽  
Dielectric Polarization ◽  
Dielectric Spectra ◽  
Equivalent Circuit Modeling ◽  
Frequency Domain Methods ◽  
The Time Domain ◽  
Paper Insulation

To assess the oil-paper insulation of transformer, it is necessary to establish the equivalent circuit for it regardless of using the time domain methods or frequency domain methods. Based on the principle of dielectric polarization, the extended Debye model is always adopted for the equivalent circuit of oil-paper insulation in transformer in most cases; however, it is usually difficult to determine the number of relaxation mechanisms in the model. This paper presents a method to determine it by the time domain dielectric spectra, namely, conduct differential operation for the depolarizing current of transformer’s oil-paper insulation to obtain the time domain dielectric spectra, and the number of spectrum peaks is equal to that of relaxation mechanisms. Thereby, the extended Debye model of the equivalent circuit of the oil-paper insulation of transformer can be built. This paper describes the analytical procedures of the time domain dielectric spectra method in detail and presents examples to validate its feasibility and rationality in determining the equivalent circuit model of transformer’s oil-paper insulation.

scholarly journals Time domain characterization of the Cole-Cole dielectric model

2020 ◽  
Vol 11 (1) ◽  
pp. 101-105
Author(s):  
Sverre Holm
Keyword(s):  
Time Domain ◽  
Real Life ◽  
Debye Model ◽  
Current Response ◽  
Debye Relaxation ◽  
Relaxation Functions ◽  
The Time Domain ◽  
Cole Model ◽  
Time Domain Characterization

AbstractThe Cole-Cole model for a dielectric is a generalization of the Debye relaxation model. The most familiar form is in the frequency domain and this manifests itself in a frequency dependent impedance. Dielectrics may also be characterized in the time domain by means of the current and charge responses to a voltage step, called response and relaxation functions respectively. For the Debye model they are both exponentials while in the Cole-Cole model they are expressed by a generalization of the exponential, the Mittag-Leffler function. Its asymptotes are just as interesting and correspond to the Curie-von Schweidler current response which is known from real-life capacitors and the Kohlrausch stretched exponential charge response.

Performance analysis of Two-class SVM to detect thin interlayer debondings within pavement structures

2020 ◽  
Author(s):  
Shreedhar Savant Todkar ◽  
Vincent Baltazart ◽  
Amine Ihamouten ◽  
Xavier Dérobert ◽  
Jean-Michel Simonin
Keyword(s):  
Sensitivity Analysis ◽  
Time Domain ◽  
Field Data ◽  
Early Stage ◽  
Simulated Data ◽  
Supervised Machine Learning ◽  
Support Vector ◽  
Destructive Testing ◽  
Signal Features ◽  
The Time Domain

<p>In the field of pavement monitoring, Ground Penetrating Radar (GPR) methods are gaining prominence due to their ability to perform non-destructive testing of the subsurface. In this context, the detection and characterization of subsurface debondings at an early stage is recommended to avoid further degradation and to maintain the lifespan of these structures. To mitigate the limited time resolution of the conventional GPR devices, this paper develops the detection of thin debonding (of millimeter-order) by monitoring small changes in the time domain GPR data by specific data processing techniques (with certain automatic capabilities).</p><p>In this paper, we propose to use the supervised machine learning method, namely Two-class Support Vector Machines (SVM) to achieve the objectives. In addition, by means of time domain GPR signal features, we aim at reducing the computational burden and also increase the efficiency of SVM. The method is implemented to process independent 1D GPR A-scan data.</p><p>Furthermore, the performance assessment of Two-class SVM is carried out on both simulated and field data by means of Sensitivity Analysis to identify the parameters that affect its performance. While simulated data is generated using the analytic Fresnel data model, the field data are UWB Stepped-Frequency GPR (SF-GPR) data which were collected over artificially embedded debondings. The data was acquired during the Accelerated Pavement Tests (APTs) conducted at the IFSTTAR's fatigue carousel to survey debonding growth in the defect-affected zones at various stages of fatigue.</p><p>Two-class SVM presented the ability to detect thin millimetric debondings. Whereas, sensitivity analysis demonstrated a quick and efficient way to assess the pavement conditions.</p>

Sign in / Sign up

Export Citation Format

Share Document