Salem Al-Ameri - Academia.edu (original) (raw)
Papers by Salem Al-Ameri
Machines
This paper presents a new investigation to detect various faults within the three-phase star and ... more This paper presents a new investigation to detect various faults within the three-phase star and delta induction motors (IMs) using a frequency response analysis (FRA). In this regard, experimental measurements using FRA are performed on three IMs of ratings 1 HP, 3 HP and 5.5 HP in normal conditions, short-circuit fault (SC) and open-circuit fault (OC) conditions. The SC and OC faults are applied artificially between the turns (Turn-to-Turn), between the coils (Coil-to-Coil) and between the phases (Phase-to-Phase). The obtained measurements show that the star and delta IMs result in dissimilar FRA signatures for the normal and faulty windings. Various statistical indicators are used to quantify the deviations between the normal and faulty FRA signatures. The calculation is performed in three frequency ranges: low, middle and high ones, as the winding parameters including resistive, inductive and capacitive components dominate the frequency characteristics at different frequency ran...
2022 2nd International Conference on Emerging Smart Technologies and Applications (eSmarTA)
Materials
Insulator monitoring using leakage current characteristics is essential for predicting an insulat... more Insulator monitoring using leakage current characteristics is essential for predicting an insulator’s health. To evaluate the risk of flashover on the porcelain insulator using leakage current, experimental investigation of leakage current indices was carried out. In the first stage of the experiment, the effect of contamination, insoluble deposit density, wetting rate, and uneven distribution pollution were determined on the porcelain insulator under test. Then, based on the laboratory test results, leakage current information in time and frequency characteristics was extracted and employed as assessment indicators for the insulator’s health. Six indicators, namely, peak current indicator, phase shift indicator, slope indicator, crest factor indicator, total harmonic distortion indicator, and odd harmonics indicator, are introduced in this work. The obtained results indicated that the proposed indicators had a significant role in evaluating the insulator’s health. To evaluate the i...
Applied Sciences
Frequency Response Analysis (FRA) technique has been recognized by worldwide utilities as a matur... more Frequency Response Analysis (FRA) technique has been recognized by worldwide utilities as a matured technology to assess the mechanical integrity of power transformers. While some industrial critical assets such as induction motors have the same construction principle as power transformers, the application of FRA technique to induction motors has not yet been fully explored. This paper presents analogical experimental studies for the application of FRA on power transformers and induction motors. For a consistent analogy, the FRA technique has been employed to detect short and open circuit turns in both appliances, which helps explore a wider scope of the FRA applications on rotating machines. In this regard, experimental FRA measurements are performed on an 11/0.415 kV, 500 kVA, three-phase distribution transformer and a 5.5 HP three-phase induction motor. Several short and open circuit faults are staged on the windings of both tested equipment and the FRA signature is recorded and ...
Scientific Reports
The monitoring of leakage current (LC) and voltage characteristics in transmission line insulator... more The monitoring of leakage current (LC) and voltage characteristics in transmission line insulators is regarded as a good technique for anticipating the physical state of in-service insulators. In the current work, the temporal and frequency characteristics of LC and voltage under various situations were derived for assessing the health condition of porcelain, glass, and silicone rubber insulators. The contamination severity indicated by soluble deposit density, wetting level (Wt), non-soluble deposit density, and uneven pollution distribution (Pu/PL) were chosen as the environmental factors that impact the insulators. Six criteria were utilized to evaluate the physical state of the insulators, with four of those derived from the LC signal in the time domain, namely, the LC signal peak (C1), the phase shift between applied voltage and LC (C2), the LC signal slope between two consecutive peaks (C3), and the crest factor (C4). The remaining two indices, namely, the total harmonics dist...
International Journal of Electrical and Electronic Engineering & Telecommunications
The transformer is critical equipment in electrical power systems as it is continuously exposed t... more The transformer is critical equipment in electrical power systems as it is continuously exposed to various failures. Inter-turns fault in the transformer reduces the turns of the winding, thus it can be detected using a transformer-turns-ratio (TTR) test. On the other hand, the Frequency Response Analysis (FRA) method is used for assessing the mechanical condition of the transformer winding and core. In this paper, the TTR, and FRA methods are proposed to detect the inter-turns fault in the transformer winding. The winding inter-turn fault was investigated using FRA inductive inter-winding measurement and compared with the TTR test. Findings from the statistical analysis showed that FRA inductive inter-winding can detect the inter-turn fault. Finally, acceptance limits for the absolute sum of logarithmic error and standard deviation were proposed. The limits were established based on TTR’s acceptance limit from the IEEE standard. This finding proves that the FRA test can be used to ...
Polymers, 2022
In this paper, a unique approach based on electrical characteristics observed from measurements o... more In this paper, a unique approach based on electrical characteristics observed from measurements of contaminated polymeric insulators was established to calculate the electric field distribution over their surfaces. A case study using two different 33 kV polymeric insulator geometric profiles was performed to highlight the benefits of the proposed modeling approach. The conductance of the pollution layer was tested to establish a nonlinear field-dependent conductivity for pollution modeling. The leakage current (LC) of the polluted insulator was measured in a laboratory under clean and wet conditions. Then, using the finite element method (FEM), the electric field and current density distributions along the insulator were computed. The results showed that the insulators experienced an increase in the electric field (EF) magnitude ranging from 0.3 kV/cm to 3.6 kV/cm for the insulator with similar sheds (type I) and 2.2–4.5 kV/cm for the insulator with alternating sheds (big and small,...
Applied Sciences, 2022
The industry has widely accepted Frequency Response Analysis (FRA) as a reliable method to detect... more The industry has widely accepted Frequency Response Analysis (FRA) as a reliable method to detect power transformers mechanical deformations. While the FRA technique has been recommended in recent literature as a potential diagnostic method to detect internal faults within rotating machines, detailed feasibility studies have not been fully addressed yet. This paper investigates the feasibility of using the FRA technique to detect several short circuit faults in the stator winding of three-phase induction motors (TPIMs). In this regard, FRA testing is conducted on two sets of induction motors with various short circuit faults. Investigated faults include short circuits between two phases, short circuit turns within the same phase, phase-to-ground, and phase-to-neutral short circuit. The measured FRA signatures are divided into three frequency ranges: low, medium, and high. Several statistical indicators are employed to quantify the variation between faulty and healthy signatures in e...
IEEE Access, 2022
Over the past decades, extensive experimental-based research works have been carried out to inves... more Over the past decades, extensive experimental-based research works have been carried out to investigate the flashover phenomenon on the performance of polluted transmission line insulators. The critical focus has been on developing methods that can determine the safety, reliability, and sustainability of the overall power transmission network based on experimental results obtained from polluted insulators' flashover voltage tests. In this paper, a systematic review of available scientific works, published as early as the 1990s, for the analysis of pollution flashover voltage, is undertaken. The review mainly focuses on factors influencing the efficiency of transmission line insulators under polluted conditions. Specifically, publication databases utilizing various synonyms and keywords associated with the terms ''contaminated insulators'' and ''flashover voltage test'' have been scrutinized. The search has resulted in 1364 articles, from which 97 articles have satisfied the review requirements and have been subsequently analyzed to determine the parameters associated with polluted insulators. Major factors that affect the performance of insulators, including electrical and environmental impacts, are discussed. Variations in factors affecting flashover test development and insulator efficiency are also considered. Overall, the current analysis provides an important insight toward successful evaluations of the health of transmission line insulators and research advancements of electric power transmission line insulators. INDEX TERMS Flashover voltage test, polluted insulators, high voltage insulators, transmission line.
Arabian Journal for Science and Engineering, 2021
This paper introduces an analytical model of contaminated insulators under critical conditions. T... more This paper introduces an analytical model of contaminated insulators under critical conditions. The dynamic mathematical model based on the description of the equivalent electrical circuit approach and the criterion for the propagation of discharge has been improved. A few laboratory tests were conducted on practical insulators installed to measure the flashover voltage and determine dynamic arc parameters (A and n). The electric arc constant values are extracted based on the simulation of the experimental results using the genetic algorithm technique with several levels of pollution. The critical parameters, which are the current, length, and resistance of discharge, have been measured and calculated based on the proposed model. The actual results of the proposed models’ voltage were compared with the experimental results and previous research study under various resistance of pollution layers. Statistical analysis based on different coefficients were applied to validate the reliability of the proposed models. The experimental and simulation findings show the insulator's expected performance under various operating conditions per the IEC 5070 Standard.
Applied Sciences, 2021
Power transformers are located in the electrical transmission and distribution networks where dif... more Power transformers are located in the electrical transmission and distribution networks where different voltage levels are needed. The turn ratio of the low voltage and high voltage windings is mechanically controlled by an on-load tap changer or de-energized tap changer. As the tap changer is the transformer’s only moving part, it is highly susceptible to mechanical failure and aging degradation. While some diagnostic tools have been used to determine the mechanical condition of tap changer contacts, not much attention was given to use the frequency response analysis to diagnose the transformer’s tap changers’ mechanical integrity. This paper is taking one step forward into maturing the application of the frequency response analysis (FRA) technique to detect transformer tap changer faults. In this regard, two common tap changer faults are created, and experimental testing for four FRA test configurations is conducted. For a better understanding of the tap changer fault mechanism, a...
2021 IEEE International Conference on the Properties and Applications of Dielectric Materials (ICPADM), 2021
This paper presents a study on the applicability of frequency response analysis (FRA) for diagnos... more This paper presents a study on the applicability of frequency response analysis (FRA) for diagnosing faulty stator winding of a three-phase induction motor. Initially, two different faults were simulated on a 2.2 kW induction motor. FRA tests were performed on the units before and after the fault to observe the influence of the fault on the response. Three statistical indicators were used to compute the amount of changes between responses. This was done on three different frequency ranges, which are low, medium, and high regions, as each region was governed by different winding parameters, namely winding resistance, inductance, and capacitance, respectively. Consequently, benchmark limits for two indicators, ASLE and CC were proposed for the estimation of normal and faulty winding conditions. Finally, the result also presents FRA measurement on 6.6 kV, 1700 kW induction motor, which clearly indicates the perfect correlation between responses, hence normal winding.
2021 IEEE International Conference on the Properties and Applications of Dielectric Materials (ICPADM), 2021
The tap changer in a power transformer plays a vital function in regulating the voltage. It has b... more The tap changer in a power transformer plays a vital function in regulating the voltage. It has been reported that the tap changer contributes to a large percentage of failures in the power transformer. This paper investigates a faulty tap changer using the frequency response analysis (FRA) test. All measurement configurations in FRA were employed to verify the effectiveness in detecting the fault. The test configurations are the end-to-end open circuit, the end-to-end short circuit, the capacitive inter-winding, and the inductive inter-winding. The coking and pitting of the tap changer are fabricated in several pieces of copper. These pieces are installed on the transformer tap selector. The FRA measurement was then performed on an 11/ 0.433 kV, 500kVA transformer at normal and faulty conditions. The variation between the FRA measurements is then calculated using the correlation coefficient (CC). This study improves the understanding of the FRA method by exploring its ability to detect tap changer faults. It is realized that the FRA method is sensitive to the tap changer coking and pitting. The results show that the tap changer coking effect at low frequencies. The response drop in magnitude at low frequencies between 20 Hz and 2 kHz. For pitting, it shows the response shifting towards higher frequencies.
IEEE Access, 2021
This work aimed to study the influence of contamination profiles and humidity on flashover electr... more This work aimed to study the influence of contamination profiles and humidity on flashover electrical characteristics of polluted insulators. Firstly, the flashover tests on cap and pin glass insulators under four pollution levels represented by salinity were conducted. Eight artificial contamination profiles based on the solid layer method have been modeled for the selected insulators. The numerical analysis has been used to determine the insulator electrical characteristics such as potential, electric field, and power dissipation under proposed contamination profiles using finite element methods (FEM). Next, the power dissipation has been simulated with consideration of thermal stress propagation in locations with high power. Finally, flashover voltage gradient tests have been conducted under various humidity and contamination profiles. The values of the flashover voltage gradient due to pollution were determined as the percentage of the value of the flashover voltage gradient in the clean condition which was identified as the reference point. The numerical model indicated that the initiation of arc generally occurs at area in which the electric field and power dissipation is maximum. It was also observed from experimental results that the flashover voltage gradient under different contamination profiles has different values depends on the location and dimension of the pollution region. INDEX TERMS Polluted insulators, contamination profiles, flashover voltage gradient, numerical model, finite element method (FEM), power dissipation.
Coatings, 2021
Based on experiments and numerical analysis techniques, this paper aims to investigate the influe... more Based on experiments and numerical analysis techniques, this paper aims to investigate the influence of the four different coating damage profiles on the performance of coated 33 kV porcelain insulator strings under polluted and clean surface conditions. The performance of the insulators coated with room temperature vulcanizing (RTV) under partial coating damage and undamaged coating was evaluated. The influence of humidity on pollution flashover was taken into consideration. The ring-shaped, fan-shaped, and random-shaped coating was applied following coating damage. The results showed that the flashover characteristic of the RTV-coated insulators had a significant difference as compared to the normal insulators. Electrical characteristics such as the flashover voltage, critical current, and surface resistance were significantly affected by coating damage distribution and humidity level on the insulators’ surface. The electric field and potential difference were analyzed as well usi...
Computers, Materials & Continua, 2021
This paper aims to assess the effect of dry band location of contaminated porcelain insulators un... more This paper aims to assess the effect of dry band location of contaminated porcelain insulators under various flashover voltages due to humidity. Four locations of dry bands are proposed to be tested under different severity of contamination artificially produce using salt deposit density (SDD) sprayed on an insulator. Laboratory tests of polluted insulators under proposed scenarios have been conducted. The flashover voltage of clean insulators has been identified as a reference value to analyze the effect of contamination distribution and its severity. The dry band dimension has been taken into consideration in experimental tests. The flashover voltage has been predicted using an artificial neural network (ANN) technique based on the laboratory test data. The ANN approach is constructed with five input data (geometry the insulator and parameters of contamination) and flashover voltage as the output of the model. Results indicated that the pollution distribution based on the proposed scenario has a significant influence on the flashover voltage performances. Validation of the ANN model reveals that the relative error values between the experimental results and the prediction appeared to be within 5%. This indicates the significant efficiency of the ANN technique in predicting the flashover voltage insulator under test.
IEEE Access, 2021
Frequency Response Analysis (FRA) is the most reliable technique currently used to evaluate the m... more Frequency Response Analysis (FRA) is the most reliable technique currently used to evaluate the mechanical integrity of power transformers. While the measurement devices have been well developed over the past two decades, interpretation of the FRA signatures is still challenging regardless of the several papers published in this regard. This paper adds an attempt to understand the power transformer FRA signatures through experimental and simulation analyses. In this context, experimental FRA measurements are conducted on a 33/11 kV, 30 MVA transformer under various faults, including winding deformation, the short circuit turns, loss of clamping, and bushing fault. At the same time, the high-frequency transformer model that comprises series capacitance, self-inductance, series resistance, and mutual inductance is simulated using MATLAB / Simulink to compare simulation and experimental results. The correlation between physical circuit parameters and various faults facilitates a better understanding of each fault's effect on the FRA signature. To quantify the impact of such faults, correlation coefficient, the absolute sum of logarithmic error, standard deviation, and sum square error are calculated with respect to the healthy signature at three frequency regions. Results show that using statistical coefficients over three frequency ranges of the FRA signature facilitates better fault identification and quantification. INDEX TERMS Power transformer, frequency response analysis, fault diagnosis, statistical indicators. NOMENCLATURE V in , V out Injected and measured voltage R in , R out Input and output Resistance R s Series resistance C s Series capacitance C t Capacitance between turns C d Capacitance between discs C g Capacitance to ground The associate editor coordinating the review of this manuscript and approving it for publication was Dazhong Ma. L s Series inductance C sHV , C sLV Series capacitance in HV and LV G s Series Conductance C gHV , C gLV Capacitance to the ground in HV, and LV winding C HL Capacitance between the HV winding and LV winding G HL Conductance between the HV winding and LV winding M km Mutual inductance
Advances in Electrical and Computer Engineering, 2020
Frequency response analysis (FRA) is a tool for evaluating mechanical integrity of transformer... more Frequency response analysis (FRA) is a tool for evaluating mechanical integrity of transformer's core and winding. However, several studies have reported that FRA is also sensitive to other parameters such as temperature, moisture content and presence of oil. Since some of these parameters are critical in the insulation degradation process, it is interesting to further investigate the possibility of using FRA for insulation assessment. In this paper, the insulation conditions of three field transformers are investigated using FRA. This is performed after statistical analysis on the response suggested no mechanical damage on the transformers. The responses are further analyzed to determine the percentage of change of winding capacitance. This is achieved by comparing resonance frequencies between the responses. The percentage of change represents the amount of degradation in the insulation. This is because as the insulation condition degrades, the response is shifted towards lower frequencies. This new investigation demonstrates the applicability of FRA to estimate the insulation degradation. © 2020 AECE
Energies, 2018
This paper presents an investigation on the sensitivity of frequency response of a 500 kVA, 11/0.... more This paper presents an investigation on the sensitivity of frequency response of a 500 kVA, 11/0.433 kV distribution transformer with and without the presence of a winding clamping structure. Frequency response analysis (FRA) measurements of multiple test configurations were carried out with and without the presence of a winding clamping structure. Statistical analyses based on Pearson’s correlation coefficient (PCC), Spearman’s correlation coefficient (SCC), Kendall’s correlation coefficient (KCC), cross-correlation coefficient (CCF), root mean square error (RMSE), absolute sum of logarithmic error (ASLE), hypothesis test (F-test) and relative factor (RF) were applied to determine the effect of the winding clamping structure. It was found that the removal of the winding clamping structure has an impact on the frequency response signature at the frequency less than 2 kHz during offline measurement. It was found that ASLE and F-test are suitable methods that can be used to indicate t...
Machines
This paper presents a new investigation to detect various faults within the three-phase star and ... more This paper presents a new investigation to detect various faults within the three-phase star and delta induction motors (IMs) using a frequency response analysis (FRA). In this regard, experimental measurements using FRA are performed on three IMs of ratings 1 HP, 3 HP and 5.5 HP in normal conditions, short-circuit fault (SC) and open-circuit fault (OC) conditions. The SC and OC faults are applied artificially between the turns (Turn-to-Turn), between the coils (Coil-to-Coil) and between the phases (Phase-to-Phase). The obtained measurements show that the star and delta IMs result in dissimilar FRA signatures for the normal and faulty windings. Various statistical indicators are used to quantify the deviations between the normal and faulty FRA signatures. The calculation is performed in three frequency ranges: low, middle and high ones, as the winding parameters including resistive, inductive and capacitive components dominate the frequency characteristics at different frequency ran...
2022 2nd International Conference on Emerging Smart Technologies and Applications (eSmarTA)
Materials
Insulator monitoring using leakage current characteristics is essential for predicting an insulat... more Insulator monitoring using leakage current characteristics is essential for predicting an insulator’s health. To evaluate the risk of flashover on the porcelain insulator using leakage current, experimental investigation of leakage current indices was carried out. In the first stage of the experiment, the effect of contamination, insoluble deposit density, wetting rate, and uneven distribution pollution were determined on the porcelain insulator under test. Then, based on the laboratory test results, leakage current information in time and frequency characteristics was extracted and employed as assessment indicators for the insulator’s health. Six indicators, namely, peak current indicator, phase shift indicator, slope indicator, crest factor indicator, total harmonic distortion indicator, and odd harmonics indicator, are introduced in this work. The obtained results indicated that the proposed indicators had a significant role in evaluating the insulator’s health. To evaluate the i...
Applied Sciences
Frequency Response Analysis (FRA) technique has been recognized by worldwide utilities as a matur... more Frequency Response Analysis (FRA) technique has been recognized by worldwide utilities as a matured technology to assess the mechanical integrity of power transformers. While some industrial critical assets such as induction motors have the same construction principle as power transformers, the application of FRA technique to induction motors has not yet been fully explored. This paper presents analogical experimental studies for the application of FRA on power transformers and induction motors. For a consistent analogy, the FRA technique has been employed to detect short and open circuit turns in both appliances, which helps explore a wider scope of the FRA applications on rotating machines. In this regard, experimental FRA measurements are performed on an 11/0.415 kV, 500 kVA, three-phase distribution transformer and a 5.5 HP three-phase induction motor. Several short and open circuit faults are staged on the windings of both tested equipment and the FRA signature is recorded and ...
Scientific Reports
The monitoring of leakage current (LC) and voltage characteristics in transmission line insulator... more The monitoring of leakage current (LC) and voltage characteristics in transmission line insulators is regarded as a good technique for anticipating the physical state of in-service insulators. In the current work, the temporal and frequency characteristics of LC and voltage under various situations were derived for assessing the health condition of porcelain, glass, and silicone rubber insulators. The contamination severity indicated by soluble deposit density, wetting level (Wt), non-soluble deposit density, and uneven pollution distribution (Pu/PL) were chosen as the environmental factors that impact the insulators. Six criteria were utilized to evaluate the physical state of the insulators, with four of those derived from the LC signal in the time domain, namely, the LC signal peak (C1), the phase shift between applied voltage and LC (C2), the LC signal slope between two consecutive peaks (C3), and the crest factor (C4). The remaining two indices, namely, the total harmonics dist...
International Journal of Electrical and Electronic Engineering & Telecommunications
The transformer is critical equipment in electrical power systems as it is continuously exposed t... more The transformer is critical equipment in electrical power systems as it is continuously exposed to various failures. Inter-turns fault in the transformer reduces the turns of the winding, thus it can be detected using a transformer-turns-ratio (TTR) test. On the other hand, the Frequency Response Analysis (FRA) method is used for assessing the mechanical condition of the transformer winding and core. In this paper, the TTR, and FRA methods are proposed to detect the inter-turns fault in the transformer winding. The winding inter-turn fault was investigated using FRA inductive inter-winding measurement and compared with the TTR test. Findings from the statistical analysis showed that FRA inductive inter-winding can detect the inter-turn fault. Finally, acceptance limits for the absolute sum of logarithmic error and standard deviation were proposed. The limits were established based on TTR’s acceptance limit from the IEEE standard. This finding proves that the FRA test can be used to ...
Polymers, 2022
In this paper, a unique approach based on electrical characteristics observed from measurements o... more In this paper, a unique approach based on electrical characteristics observed from measurements of contaminated polymeric insulators was established to calculate the electric field distribution over their surfaces. A case study using two different 33 kV polymeric insulator geometric profiles was performed to highlight the benefits of the proposed modeling approach. The conductance of the pollution layer was tested to establish a nonlinear field-dependent conductivity for pollution modeling. The leakage current (LC) of the polluted insulator was measured in a laboratory under clean and wet conditions. Then, using the finite element method (FEM), the electric field and current density distributions along the insulator were computed. The results showed that the insulators experienced an increase in the electric field (EF) magnitude ranging from 0.3 kV/cm to 3.6 kV/cm for the insulator with similar sheds (type I) and 2.2–4.5 kV/cm for the insulator with alternating sheds (big and small,...
Applied Sciences, 2022
The industry has widely accepted Frequency Response Analysis (FRA) as a reliable method to detect... more The industry has widely accepted Frequency Response Analysis (FRA) as a reliable method to detect power transformers mechanical deformations. While the FRA technique has been recommended in recent literature as a potential diagnostic method to detect internal faults within rotating machines, detailed feasibility studies have not been fully addressed yet. This paper investigates the feasibility of using the FRA technique to detect several short circuit faults in the stator winding of three-phase induction motors (TPIMs). In this regard, FRA testing is conducted on two sets of induction motors with various short circuit faults. Investigated faults include short circuits between two phases, short circuit turns within the same phase, phase-to-ground, and phase-to-neutral short circuit. The measured FRA signatures are divided into three frequency ranges: low, medium, and high. Several statistical indicators are employed to quantify the variation between faulty and healthy signatures in e...
IEEE Access, 2022
Over the past decades, extensive experimental-based research works have been carried out to inves... more Over the past decades, extensive experimental-based research works have been carried out to investigate the flashover phenomenon on the performance of polluted transmission line insulators. The critical focus has been on developing methods that can determine the safety, reliability, and sustainability of the overall power transmission network based on experimental results obtained from polluted insulators' flashover voltage tests. In this paper, a systematic review of available scientific works, published as early as the 1990s, for the analysis of pollution flashover voltage, is undertaken. The review mainly focuses on factors influencing the efficiency of transmission line insulators under polluted conditions. Specifically, publication databases utilizing various synonyms and keywords associated with the terms ''contaminated insulators'' and ''flashover voltage test'' have been scrutinized. The search has resulted in 1364 articles, from which 97 articles have satisfied the review requirements and have been subsequently analyzed to determine the parameters associated with polluted insulators. Major factors that affect the performance of insulators, including electrical and environmental impacts, are discussed. Variations in factors affecting flashover test development and insulator efficiency are also considered. Overall, the current analysis provides an important insight toward successful evaluations of the health of transmission line insulators and research advancements of electric power transmission line insulators. INDEX TERMS Flashover voltage test, polluted insulators, high voltage insulators, transmission line.
Arabian Journal for Science and Engineering, 2021
This paper introduces an analytical model of contaminated insulators under critical conditions. T... more This paper introduces an analytical model of contaminated insulators under critical conditions. The dynamic mathematical model based on the description of the equivalent electrical circuit approach and the criterion for the propagation of discharge has been improved. A few laboratory tests were conducted on practical insulators installed to measure the flashover voltage and determine dynamic arc parameters (A and n). The electric arc constant values are extracted based on the simulation of the experimental results using the genetic algorithm technique with several levels of pollution. The critical parameters, which are the current, length, and resistance of discharge, have been measured and calculated based on the proposed model. The actual results of the proposed models’ voltage were compared with the experimental results and previous research study under various resistance of pollution layers. Statistical analysis based on different coefficients were applied to validate the reliability of the proposed models. The experimental and simulation findings show the insulator's expected performance under various operating conditions per the IEC 5070 Standard.
Applied Sciences, 2021
Power transformers are located in the electrical transmission and distribution networks where dif... more Power transformers are located in the electrical transmission and distribution networks where different voltage levels are needed. The turn ratio of the low voltage and high voltage windings is mechanically controlled by an on-load tap changer or de-energized tap changer. As the tap changer is the transformer’s only moving part, it is highly susceptible to mechanical failure and aging degradation. While some diagnostic tools have been used to determine the mechanical condition of tap changer contacts, not much attention was given to use the frequency response analysis to diagnose the transformer’s tap changers’ mechanical integrity. This paper is taking one step forward into maturing the application of the frequency response analysis (FRA) technique to detect transformer tap changer faults. In this regard, two common tap changer faults are created, and experimental testing for four FRA test configurations is conducted. For a better understanding of the tap changer fault mechanism, a...
2021 IEEE International Conference on the Properties and Applications of Dielectric Materials (ICPADM), 2021
This paper presents a study on the applicability of frequency response analysis (FRA) for diagnos... more This paper presents a study on the applicability of frequency response analysis (FRA) for diagnosing faulty stator winding of a three-phase induction motor. Initially, two different faults were simulated on a 2.2 kW induction motor. FRA tests were performed on the units before and after the fault to observe the influence of the fault on the response. Three statistical indicators were used to compute the amount of changes between responses. This was done on three different frequency ranges, which are low, medium, and high regions, as each region was governed by different winding parameters, namely winding resistance, inductance, and capacitance, respectively. Consequently, benchmark limits for two indicators, ASLE and CC were proposed for the estimation of normal and faulty winding conditions. Finally, the result also presents FRA measurement on 6.6 kV, 1700 kW induction motor, which clearly indicates the perfect correlation between responses, hence normal winding.
2021 IEEE International Conference on the Properties and Applications of Dielectric Materials (ICPADM), 2021
The tap changer in a power transformer plays a vital function in regulating the voltage. It has b... more The tap changer in a power transformer plays a vital function in regulating the voltage. It has been reported that the tap changer contributes to a large percentage of failures in the power transformer. This paper investigates a faulty tap changer using the frequency response analysis (FRA) test. All measurement configurations in FRA were employed to verify the effectiveness in detecting the fault. The test configurations are the end-to-end open circuit, the end-to-end short circuit, the capacitive inter-winding, and the inductive inter-winding. The coking and pitting of the tap changer are fabricated in several pieces of copper. These pieces are installed on the transformer tap selector. The FRA measurement was then performed on an 11/ 0.433 kV, 500kVA transformer at normal and faulty conditions. The variation between the FRA measurements is then calculated using the correlation coefficient (CC). This study improves the understanding of the FRA method by exploring its ability to detect tap changer faults. It is realized that the FRA method is sensitive to the tap changer coking and pitting. The results show that the tap changer coking effect at low frequencies. The response drop in magnitude at low frequencies between 20 Hz and 2 kHz. For pitting, it shows the response shifting towards higher frequencies.
IEEE Access, 2021
This work aimed to study the influence of contamination profiles and humidity on flashover electr... more This work aimed to study the influence of contamination profiles and humidity on flashover electrical characteristics of polluted insulators. Firstly, the flashover tests on cap and pin glass insulators under four pollution levels represented by salinity were conducted. Eight artificial contamination profiles based on the solid layer method have been modeled for the selected insulators. The numerical analysis has been used to determine the insulator electrical characteristics such as potential, electric field, and power dissipation under proposed contamination profiles using finite element methods (FEM). Next, the power dissipation has been simulated with consideration of thermal stress propagation in locations with high power. Finally, flashover voltage gradient tests have been conducted under various humidity and contamination profiles. The values of the flashover voltage gradient due to pollution were determined as the percentage of the value of the flashover voltage gradient in the clean condition which was identified as the reference point. The numerical model indicated that the initiation of arc generally occurs at area in which the electric field and power dissipation is maximum. It was also observed from experimental results that the flashover voltage gradient under different contamination profiles has different values depends on the location and dimension of the pollution region. INDEX TERMS Polluted insulators, contamination profiles, flashover voltage gradient, numerical model, finite element method (FEM), power dissipation.
Coatings, 2021
Based on experiments and numerical analysis techniques, this paper aims to investigate the influe... more Based on experiments and numerical analysis techniques, this paper aims to investigate the influence of the four different coating damage profiles on the performance of coated 33 kV porcelain insulator strings under polluted and clean surface conditions. The performance of the insulators coated with room temperature vulcanizing (RTV) under partial coating damage and undamaged coating was evaluated. The influence of humidity on pollution flashover was taken into consideration. The ring-shaped, fan-shaped, and random-shaped coating was applied following coating damage. The results showed that the flashover characteristic of the RTV-coated insulators had a significant difference as compared to the normal insulators. Electrical characteristics such as the flashover voltage, critical current, and surface resistance were significantly affected by coating damage distribution and humidity level on the insulators’ surface. The electric field and potential difference were analyzed as well usi...
Computers, Materials & Continua, 2021
This paper aims to assess the effect of dry band location of contaminated porcelain insulators un... more This paper aims to assess the effect of dry band location of contaminated porcelain insulators under various flashover voltages due to humidity. Four locations of dry bands are proposed to be tested under different severity of contamination artificially produce using salt deposit density (SDD) sprayed on an insulator. Laboratory tests of polluted insulators under proposed scenarios have been conducted. The flashover voltage of clean insulators has been identified as a reference value to analyze the effect of contamination distribution and its severity. The dry band dimension has been taken into consideration in experimental tests. The flashover voltage has been predicted using an artificial neural network (ANN) technique based on the laboratory test data. The ANN approach is constructed with five input data (geometry the insulator and parameters of contamination) and flashover voltage as the output of the model. Results indicated that the pollution distribution based on the proposed scenario has a significant influence on the flashover voltage performances. Validation of the ANN model reveals that the relative error values between the experimental results and the prediction appeared to be within 5%. This indicates the significant efficiency of the ANN technique in predicting the flashover voltage insulator under test.
IEEE Access, 2021
Frequency Response Analysis (FRA) is the most reliable technique currently used to evaluate the m... more Frequency Response Analysis (FRA) is the most reliable technique currently used to evaluate the mechanical integrity of power transformers. While the measurement devices have been well developed over the past two decades, interpretation of the FRA signatures is still challenging regardless of the several papers published in this regard. This paper adds an attempt to understand the power transformer FRA signatures through experimental and simulation analyses. In this context, experimental FRA measurements are conducted on a 33/11 kV, 30 MVA transformer under various faults, including winding deformation, the short circuit turns, loss of clamping, and bushing fault. At the same time, the high-frequency transformer model that comprises series capacitance, self-inductance, series resistance, and mutual inductance is simulated using MATLAB / Simulink to compare simulation and experimental results. The correlation between physical circuit parameters and various faults facilitates a better understanding of each fault's effect on the FRA signature. To quantify the impact of such faults, correlation coefficient, the absolute sum of logarithmic error, standard deviation, and sum square error are calculated with respect to the healthy signature at three frequency regions. Results show that using statistical coefficients over three frequency ranges of the FRA signature facilitates better fault identification and quantification. INDEX TERMS Power transformer, frequency response analysis, fault diagnosis, statistical indicators. NOMENCLATURE V in , V out Injected and measured voltage R in , R out Input and output Resistance R s Series resistance C s Series capacitance C t Capacitance between turns C d Capacitance between discs C g Capacitance to ground The associate editor coordinating the review of this manuscript and approving it for publication was Dazhong Ma. L s Series inductance C sHV , C sLV Series capacitance in HV and LV G s Series Conductance C gHV , C gLV Capacitance to the ground in HV, and LV winding C HL Capacitance between the HV winding and LV winding G HL Conductance between the HV winding and LV winding M km Mutual inductance
Advances in Electrical and Computer Engineering, 2020
Frequency response analysis (FRA) is a tool for evaluating mechanical integrity of transformer... more Frequency response analysis (FRA) is a tool for evaluating mechanical integrity of transformer's core and winding. However, several studies have reported that FRA is also sensitive to other parameters such as temperature, moisture content and presence of oil. Since some of these parameters are critical in the insulation degradation process, it is interesting to further investigate the possibility of using FRA for insulation assessment. In this paper, the insulation conditions of three field transformers are investigated using FRA. This is performed after statistical analysis on the response suggested no mechanical damage on the transformers. The responses are further analyzed to determine the percentage of change of winding capacitance. This is achieved by comparing resonance frequencies between the responses. The percentage of change represents the amount of degradation in the insulation. This is because as the insulation condition degrades, the response is shifted towards lower frequencies. This new investigation demonstrates the applicability of FRA to estimate the insulation degradation. © 2020 AECE
Energies, 2018
This paper presents an investigation on the sensitivity of frequency response of a 500 kVA, 11/0.... more This paper presents an investigation on the sensitivity of frequency response of a 500 kVA, 11/0.433 kV distribution transformer with and without the presence of a winding clamping structure. Frequency response analysis (FRA) measurements of multiple test configurations were carried out with and without the presence of a winding clamping structure. Statistical analyses based on Pearson’s correlation coefficient (PCC), Spearman’s correlation coefficient (SCC), Kendall’s correlation coefficient (KCC), cross-correlation coefficient (CCF), root mean square error (RMSE), absolute sum of logarithmic error (ASLE), hypothesis test (F-test) and relative factor (RF) were applied to determine the effect of the winding clamping structure. It was found that the removal of the winding clamping structure has an impact on the frequency response signature at the frequency less than 2 kHz during offline measurement. It was found that ASLE and F-test are suitable methods that can be used to indicate t...