Power Frequency Electromagnetic Fields Research Articles

Dual-Functional Cross-Meandering Resonator for Power Frequency Electromagnetic Shielding and Wireless Sensing Communication.

The research on MEMS wireless sensing technology adapted to strong power frequency electromagnetic field environments is of great significance to our energy security, economic society, and even national security. Here, we propose a subwavelength cross-meandering resonator (0.49λ0 × 0.49λ0) to simultaneously achieve power frequency electromagnetic field shielding and wireless communication signal transmission. The element size of the resonator is only λ0/11, which is much smaller than that of previous works. In the resonator, a resonance mode with the significant near-field enhancement effect (about 180 times that at f = 1 GHz) is supported. Based on the self-made shielding box experimental setup, the measured shielding effectiveness of the resonator sample can reach more than 33 dB. Moreover, by integrating the cross-meandering resonator with the MEMS sensor, a wireless communication signal can be successfully transmitted. A dual-function cross-meandering resonator integrated with sensors may find potential applications in many military and civilian industries associated with strong power frequency electromagnetic fields.

A granularity data method for power frequency electric and electromagnetic fields forecasting based on T–S fuzzy model

The impact of electromagnetic radiation generated by signal transmission base stations and power stations to meet the needs of communication equipment and energy consumption on the environment has caused people concerns. Monitoring and prediction of electric and magnetic fields have become critical tasks for researchers. In this paper, we propose a granularity data method based on T–S (Takagi–Sugeno) fuzzy model, named fuzzy rule-based model, which utilizing finite rules that are determined by the deviations between the predicted values and the true values after the data goes through a granulation-degranulation mechanism, to predict the intensity of power frequency electric field and electromagnetic field. A series of experiments show that fuzzy rule-based models have better robustness and higher prediction accuracy in comparison with several existing prediction models. The improvement of the performance of the fuzzy rule-based model quantified in terms of Root Mean Squared Error is 20.86%, 51.91%, 62.28%, 65.10%, and 71.92% in comparison with that of the Ridge model, Lasso model, and a family of support vector machine model with different kernel functions, including linear kernel (SVM-linear), radial basis function (SVM-BRF), polynomial kernel (SVM-polynomial) respectively, on the electromagnetic field testing data, and 37.42%, 55.16%, 58.79%, 59.28%, 64.27% lower than that of the Ridge model, Lasso model, SVM-linear model, SVM-BRF model and SVM-polynomial model on the power frequency electric field testing data.

Electromagnetic Environment Assessment and Safety Research of Electrified High-Speed Railway Carriages

With the advent of modern, high-speed electrified rail systems, there has been increasing concern about electromagnetic safety in rail carriages. The aim of this study was to assess the electromagnetic safety of passengers on trains by utilizing advanced 3D electromagnetic simulation software. A comprehensive model of the electromagnetic environment experienced by passengers on a CR400AF train, specifically under the influence of catenary radiation, was constructed. We analyzed the magnetic field strength, electric field strength, and current density in the brains of 20 passengers in various positions in the train. The findings revealed that among the 20 passengers analyzed, the maximum and minimum magnetic induction intensity recorded in the brain were 8.41 and 0.01 μT, respectively. The maximum and minimum induced electric field intensities were 1110 and 10 μV/m, respectively. Lastly, the maximum and minimum induced current densities were 1200 and 10 μA/m2, respectively. The results show that when people ride on the CR400AF train, the magnetic induction intensity, induced electric field strength, and induced current density in the brain are below the recommended basic limits of exposure to power frequency electromagnetic fields in the guidelines of the International Committee on Non-Ionizing Radiation Protection. The power frequency magnetic field generated by the catenary can be effectively shielded by the aluminum alloy car body. The final result of this study indicates that the electromagnetic exposure from the contact wire at the level 25 kV does not pose a threat to the health of passengers on the CR400AF train.

One-dimensional parallel forward modeling for geophysical electromagnetic fields excited by sagging overhead transmission lines

Geophysicists often regard the 50/60 Hz electromagnetic (EM) waves and their harmonics, excited by overhead transmission lines, as noise that interferes with geophysical prospecting. However, some researchers view them as effective signals for geophysical exploration. Forward modeling can be used to study the characteristics of EM fields generated by overhead transmission lines. It can help in either eliminating or utilizing power-frequency EM fields. Nevertheless, current research on the forward modeling of EM fields excited by transmission lines neglects the sagging shape and direction of the actual transmission lines, simplifying them into infinitely long straight lines. In this research, we develop a one-dimensional forward modeling algorithm specifically designed for overhead transmission lines, which can accurately calculate the EM fields excited by realistic overhead transmission lines considering the three-phase system, design parameters, sag, and orientation of the transmission lines. To construct an accurate transmission line model, we represent the sagging shape of a single transmission line within a span by a catenary equation. We then derive analytical expressions for the EM fields excited by sagging overhead transmission lines. During forward modeling, an appropriate number of Gauss points must be selected to balance accuracy and speed. The optimal number of Gauss points is determined based on the distance between the observation point and the transmission line source, as well as the type of fields being calculated. OpenMP parallelization is used to improve computational speed. The forward modeling results reveal significant differences between the forward responses of a single infinitely long straight line and realistic transmission lines. This highlights the importance of fully incorporating the three-phase system, design parameters, and geometric shapes of transmission lines in the forward modeling process. Moreover, the inversion test demonstrates the potential utility of EM fields radiated by transmission lines for geophysical exploration.

Calculation and test analysis for power frequency electromagnetic field of transmission line crossing agricultural greenhouse area

To assess the electromagnetic environment (EME) of high-voltage AC transmission lines (TLs) across agricultural greenhouses (AGs), a program that can calculate the power frequency electromagnetic field (PFEMF) under various AC TLs is compiled based on the principle of the simulated charge method and the simulated current method, and the power frequency electric field (PFEF) and magnetic field (MF) strength of AGs are calculated and compared with the field measurement results. The results show that the field measurement values of PFEF intensity and magnetic induction intensity in AGs do not exceed the standard requirements of 10kV/m and 0.1mT. The existence of AGs has a certain influence on the electric field (EF) distribution, but has little influence on the power frequency magnetic field (PFMF). For the PFEF and PFMF in AGs, the numerical calculation results are basically consistent with the field measurement results. The above results provide a reference for the EME assessment of high-voltage AC TLs across AGs.

Measurement and Test of Electromagnetic Environment of Power Transmission and Transformation Project Based on Full Humidity Condition

Currently, the power transmission engineering electromagnetic environment monitoring instrument is widely used but cannot realize the power frequency electric field monitoring if the humidity is above 80%. By analyzing the influence factors of the humidity on the measuring instrument, this paper puts forward the power frequency electromagnetic field measurement method in the full humidity condition. The comparison test and data analysis are carried out under different humidity conditions. The distribution characteristic curve of the power frequency electric field is calculated by Maxwell software, and the accuracy of the measured data is verified from the theoretical calculation. The analysis proves that the power frequency electromagnetic field is independent of the environmental humidity, which strongly supports the electromagnetic environment measurement on rainy days of high humidity weather conditions.

Научно-методические основы физиолого-гигиенической оценки термической нагрузки среды с учетом использования средств индивидуальной защиты от электрических полей промышленной частоты на высоковольтных объектах

Due to the new technologies and power networks development, the number of extremely high-voltage power frequency sources increases. These sources may affect the human nervous, cardio-vascular systems as well as vision. Maintenance, repair, and adjustment of high-voltage equipment is carried out by the electricotechnical staff. Electrotechnical staff is exposed to power frequency electric field from the switchyards and overhead transmission lines where permissible limit values are exceeded. Human health protection from the harmful power frequency electromagnetic field effects is an actual issue of the occupational safety. Staff safety work must be provided by use of the personal protective equipment from unfavorable and hazard occupational factors. Usual personal protective equipment is the conductive suit, which includes conductive clothes, facescreen, gloves and footwear. Screening property of the personal protective equipment are based on the principle of Faraday cage, which is realized by the conductive materials. These materials and personal protective equipment need to have optimal air permeability and water vapor transmission properties. In accordance with the possible work outdoors, in the warm season especially, electrotechnical staff is exposed not only to the main harmful occupational factor, and climatic environments too, such as air temperature, its movement speed, humidity. Personal protective equipment development requires complex multifactorial assessment with special attention to the human body physical load value, his functional state, metabolic parameters, as well as suit thermal insulation.

Design of electromagnetic induction calculation and auxiliary calculation software under UHV transmission line

With the development of 1000 kV UHV transmission technology and the shortage of line corridor resources, UHV will inevitably cross the building area. Although many scholars had studied the power frequency electromagnetic field under UHV AC transmission line, it is very difficult to accurately calculate the electric field strength and induced voltage, which cannot be applied in engineering. At present, there is no relevant literature to study the problem of induced electricity in buildings with a large number of steel frame structures under the line and the estimation method of induced electricity in buildings. By summarizing and analyzing the simulation data, the estimation method of induced voltage and induced current density of steel frame buildings under UHV lines was proposed. An auxiliary calculation system was developed. The calculated values of the software were compared with the measured values, which accuracy of voltage and current can reach 91.5% and 92.7%, and fully meet the engineering needs.

Effect of the Power-Frequency Electromagnetic Field on the Physicochemical Properties of Aluminum Micro- and Nanopowders

Effect of the Power-Frequency Electromagnetic Field on the Physicochemical Properties of Aluminum Micro- and Nanopowders

Electromagnetic field cancer risk epidemiological studies experience in the Russian Federation

Introduction. Based on the urgency of the problem of workers and general public risk of malignant neoplasms due to power frequency (PF) electromagnetic fields (EMF) impact, which led to research on its role in leukemia development expansion in all countries, the data of 4 similar studies of the Institute of occupational health are summarized. The aim of the study is to assess the risk of hemoblastosis in workers and general public under EMF occupational and non-occupational exposure. Materials and methods. 4 analytical epidemiological studies were performed: 2 cohort studies and 2 case - control studies. Results. Cohort study of 500 kV electric grid facilities personnel mortality, taking into account the electric (EF) and magnetic field (MF) exposure values, showed that the standardized relative risk (SRR) of death from all causes was 0.61; from cardiovascular diseases - 0.54, malignancies - 0.89, accidents, injuries and poisoning - 0.95. At the same time, from leukemia, SRR was increased by 2 times compared to the control (2.03), but statistically insignificant (95% CI 0.23-7.31). Retrospective case - control cancer-epidemiological study aimed at assessing the relationship between hemoblastosis various forms development and PF EMF occupational revealed to statistically unreliable increase of leukemia developing relative risk (OR) (1.64). MF mainly exposed personnel were found to have an increased risk of lymphomas developing (2.92), which was statistically significant (χ2 >3,84). Cancer-epidemiological case-control study to identify a causal relationship between parents occupational EMF exposure and childhood hemoblastosis development revealed the tendency to increase the risk, more pronounced in case of fathers MF exposure as well as high-voltage equipment EMF exposure (OR=4.6 95% CI 0.6-35.0 and OR=2.7 CI 0.9-7.8). In the study of mortality of living in the vicinity of 500 and 750 kV substations and overhead transmission lines population, due to low mortality from all causes of death, there was standardized risk of death from leukemia statistically nonsignificant increased (SR-1,3 95% CI 0,2-7,0). Conclusion. The results of studies showed a tendency to increase the risk of dying from hemoblastosis against the background of low mortality rates from other classes of diseases, which coincides with the main conclusions of most foreign publications on the problem.

The mitochondria/caspase-dependent apoptotic pathway plays a role in the positive effects of a power frequency electromagnetic field on Alzheimer’s disease neuronal model

In this study, rat pheochromocytoma (PC12) cells were induced into an Alzheimer’s Disease (AD) neuronal model using nerve growth factor (NGF; 50 ng/mL) and Amyloid β25–35 (20 μmol/L). Changes in the morphological structure, cell viability, apoptosis rate, and expression of apoptosis-related protein induced by exposure to a power frequency electromagnetic field (PF-MF; 50 Hz, 100 μT, 24 h) were detected respectively by light and electron microscopy, the MTT assay, immunohistochemistry, flow cytometry and enzyme-linked immunosorbent assays. The results showed that 3−12 h after PF-MF exposure, the pathological injury was improved partly; metabolic activity was promoted and cell apoptosis was inhibited in the AD neuronal model. In addition, PF-MF exposure significantly inhibited the expression of Caspase8, Caspase3, and CytC, but increased the Bcl-2/Bax ratio of the AD neuronal model. Meanwhile, PF-MF seemed to have no effect on the expression of Fas and TNFR1. This study indicated that the mitochondria/caspase-dependent apoptotic pathway plays an important role in the positive effects of PF-MF on an AD neuronal model. The results suggested that PF-MF exposure might have potential therapeutic value for AD, and the underling molecular mechanisms still need further studies.

An Investigation Into the Effects of Long-Term 50-Hz Power-Frequency Electromagnetic Field Exposure on Hematogram, Blood Chemistry, Fibrosis, and Oxidant Stress Status in the Liver and the Kidney From Sprague-Dawley Rats.

Power-frequency electromagnetic fields (PF-EMFs) at 50 Hz are potential health risk factors. This study aimed to explore the effects of long-term exposure to 50-Hz PF-EMFs on general physiological conditions in Sprague-Dawley (SD) rats. During a 24-week exposure period, the body mass and water and food intake of the animals were recorded regularly. The hematologic parameters were detected every 12 weeks, and blood chemistry analyses were performed every 4 weeks. After sacrifice, morphology was identified by hematoxylin-eosin, Masson, and immunohistochemical staining. Fibrosis-related gene expression and oxidative stress status were also detected. Compared with the control group, exposure to 30, 100, or 500 μT PF-EMF did not exert any effect on body mass, food intake, or water intake. Similarly, no significant differences were found in hematologic parameters or blood chemistry analyses among these groups. Furthermore, morphological assays showed that exposure to PF-EMFs had no influence on the structure of the liver or kidney. Finally, fibrosis-related gene expression and oxidative stress status were unaltered by PF-EMF exposure. The present study indicates that 24 weeks of exposure to PF-EMFs at intensities of 30, 100, or 500 μT might not affect hemograms, blood chemistry, fibrosis, or oxidative stress in the liver or kidney in SD rats. © 2020 Bioelectromagnetics Society.

Study on electromagnetic environment of ±800 kV UHV DC and 1000 kV UHV AC parallel transmission lines

Aiming at the typical AC/DC parallel transmission lines which have been put into operation in China, the electromagnetic environment of parallel transmission lines is monitored and the interaction between AC and DC electromagnetic environment is analyzed. Monitoring results show that: The electromagnetic environment of UHV AC/DC parallel transmission lines meets the corresponding national standard limits. UHV DC transmission line has little influence on power frequency electromagnetic field, which is mainly affected by distance and wire height to ground. UHV AC transmission line may have a certain impact on DC composite field strength, and wind speed will have a greater impact on DC composite field strength.

The pattern of power frequency electromagnetic fields in the Pushkin municipal area of Saint Petersburg

The study of patterns of electric fields intensity indicators and amagnetic induction in the Pushkin municipal area of Saint Petersburg has been executed. It is established that intensity of electric fields reaches significant sizes only near to air high-voltage transmission lines. Magnetic induction over admissible levels is not noted, but within city territory its size change largely that had been represented on the original map. The dependence of indicators of magnetic induction on the land use and building of territories in Pushkin is rather simple: the minimum values are registered in the parks, squares and boulevards, the averages are in the built-up territories, the raised are in anomalies. Magnitudes over hygienic standard are not noted. Magnitudes over the approximate safer limit 400nTl are observed in Pushkin area only in places of underground cables. As awhole, the Pushkin area is characterized by the indicators of magnetic induction lowered in comparison with another cities.

Preparation of silver-coated copper electromagnetic shielding coating and its application in power frequency electromagnetic field

In this paper, the shielding effectiveness of the electromagnetic shielding composite coating with copper powder and silver coated copper powder as the base material was tested by preparing the polyurethane matrix with 0.95∼1.01 isocyanate index and adding flaky ferro-silico-aluminium powder. The field comparison experiment shows that the silver-clad copper-based electromagnetic shielding composite coating has a good efficiency of power frequency electromagnetic shielding, which is up to 30.71dB. It has a broad application prospect in the field of electromagnetic protection of power transmission and transformation facilities.

Power Frequency Electromagnetic Fields in the Urban Environment as the Object of Ecological-Geographical Research

The spatial distribution and temporal dynamics of industrial frequency electric and magnetic fields in St. Petersburg, Kazan, Belgorod and Petrozavodsk has been studied. It is established that electric fields of significant strengths occur near high voltage transmission lines (HVL) only. It is found that sanitary-protection and exclusion zones of the standard size do not always ensure a decrease in electric field strength to maximum allowable levels on their boundaries. Thus, the electric field strength of four HVL in St. Petersburg increases due to the mass construction of high-rise buildings leading to an increase in power consumption. A dependence of the electric field strength on meteorological factors was also determined, primarily on air humidity (direct dependence), and on atmospheric pressure (indirect inverse relationship). The industrial frequency magnetic field produces a variable city-wide background caused by a set of sources. The more intense is the technogenic load, the higher is magnetic induction, which renders it a convenient geoindicator for mapping. Also, the indicators of magnetic induction reflect the characteristics of power networks. Abnormally high values of magnetic induction were recorded in all cities, which are explained by the influence of electric cables. No exceedances of allowable levels of magnetic induction in residential areas were observed.

Power frequency electromagnetic fields in the urban environment as the object of ecological-geographical research.

Power frequency electromagnetic fields in the urban environment as the object of ecological-geographical research.

Long term power frequency electromagnetic fields exposure influences the causal network connection pattern of local field potentials during working memory

The possible influence of electromagnetic field (EMF) on the function of neural systems has been widely concerned. In this article, we intend to investigate the effects of long term power frequency EMF exposure on brain cognitive functions and it's mechanism. The Sprague-Dawley (SD) rats were randomly divided into 3 groups: the rats in EMF Ⅰ group were placed in the 2 mT power frequency EMF for 24 days. The rats in EMF Ⅱ group were placed in the 2 mT power frequency EMF for 48 days. The rats in control group were not exposed to the EMF. Then, the 16 channel local field potentials (LFPs) were recorded from rats' prefrontal cortex (PFC) in each group during the working memory (WM) tasks. The causal networks of LFPs were also established by applying the directed transfer function (DTF). Based on that, the differences of behavior and the LFPs network connection patterns between different groups were compared in order to investigate the influence of long term power frequency EMF exposure on working memory. The results showed the rats in the EMF Ⅱ group needed more training to reach the task correction criterion (over 80%). Moreover, the causal network connection strength and the global efficiency of the rats in EMF Ⅰ and EMF Ⅱ groups were significantly lower than the corresponding values of the control group. Meanwhile, significant differences of causal density values were found between EMF Ⅱ group and the other two groups. These results indicate that long term exposure to 2 mT power frequency EMF will reduce the connection strength and the information transfer efficiency of the LFPs causal network in the PFC, as well as the behavior performance of the rats. These results may explain the effect of EMF exposure on working memory from the view of neural network connectivity and provide a support for further studies on the mechanism of the effect of EMF on cognition.

Evaluation uncertainty of power frequency electric field for a Power Project in inner Mongolia

Objective: With the measurement and uncertainty analysis of the power frequency electric field of the main transformer in the power station, the source of uncertainty, its quantitative calculation, the synthetic assessment method and the reporting method of the measurement results are described to ensure the reliability of the power frequency electric field measurement data. Methods: Referring to the "Measurement of power frequency electric field in the workplace" (GBZ/T189.3-2007) , "Labour environment monitoring technological specification of electric power industry Partt7: Monitoring of power frequency electromagnetic fields" (DL/T 799.7-2010) and "Evaluation and Expression of Uncertainty in Measurement" (JJF 1059.1-2012) , the uncertainty of power frequency electric field measurement data of the main transformer of a power plant was analyzed and the extended uncertainty was obtained. Results: The main source of the uncertainty of power frequency electric field measurement was the measurement of repetitive operation, and the expanded uncertainty of power frequency electric field was 0.09 kV/m. Conclusion: When reporting the results of power frequency electric field measurement, the measurement uncertainty should be used simultaneously to quantify the quality of the measurement results. This method has strong practicability and operability, which can meet the requirements of uncertainty evaluation of power frequency electric field measurement results.

Eotaxin‑1 and MCP‑1 serve as circulating indicators in response to power frequency electromagnetic field exposure in mice.

The increasing public concern regarding the potential health risks of exposure to electromagnetic fields (EMFs) has led to intensive research in this area. However, it remains unclear whether potential pro-oncogenic effects may be caused by power frequency EMF (PFEMF) exposure. To address the associated risk factors, the present study exposed 4-week old Balb/c mice to 0, 0.1, 0.5 and 2.5 mT of constant 50 Hz Helmholtz coil-type PFEMF for 90 days to explore the circulating chemokine indicators that may be associated with inflammation or cancer. No measurable weight difference existed between the control and PFEMF-exposure groups; however, the Luminex assay clearly demonstrated differentially responsive profiles of circulating chemokines upon PFEMF treatment. Monocyte chemoattractant protein (MCP)-3, macrophage inflammatory protein (MIP)-1α, MIP-1β and MIP-2 levels in serum were not significantly altered by PFEMF during the 3-month exposure period; however, the circulating levels of other chemokines including IP-10, GROα, RANTES, EOTAXIN-1 and MCP-1 exhibited significant changes upon treatment. Among the responsive chemokines, EOTAXIN-1 and MCP-1 were significantly increased by 0.5 mT of PFEMF treatment, which may support their use as indicators of PFEMF exposure. This novel finding highlights the potential pro-inflammatory nature of power frequency, which may shed light on the mechanisms underlying PFEMF-induced diseases, including cancer.