scholarly journals Performance of UV and IR Sensors for Inspections of Power Equipment

2019 ◽  
pp. 82-87 ◽  
Author(s):  
Gernot Komar ◽  
Oliver Pischler ◽  
Uwe Schichler ◽  
Radu-Laurentiu Vieriu
Keyword(s):  
Transmission Lines ◽  
Thermal Effects ◽  
Power Transmission ◽  
Ir Camera ◽  
The Past ◽  
Transmission Equipment ◽  
Solar Blind ◽  
Measurement Results ◽  
Ir Sensors ◽  
Measurement Practices

Electric power infrastructure, such as transmission lines or substations, is usually routinely inspected to assess its condition. The vast majority of typical defects in power transmission equipment manifests itself either through corona phenomena or through thermal effects. Therefore, an IR camera and a solar blind UV camera are sufficient for the detection of most defects in power transmission equipment. In the past, many network operators have relied mostly on manual inspections. In recent years, however, manned as well as unmanned aerial inspection methods, which are significantly more time effective, have become increasingly affordable and are therefore gaining in popularity rapidly.To obtain meaningful measurement results, many factors must be taken into account, which can even be difficult with conventional, static measurements. In the case of highly dynamic measurement practices (airborne or vehicle based), the combination of velocity and distance presents further challenges.This contribution is focused on the detection performance of UV and IR sensors under dynamic conditions. For this purpose, experiments were carried out with a typical IR and UV/corona camera at various distances to artificial defects. Additionally, a method for the automatic evaluation of UV und IR data based on machine learning is presented.

Biological Hazards of Microwave Radiation

1980 ◽  
Vol 43 (8) ◽  
pp. 625-628 ◽  
Author(s):  
JOHN P. LAMBERT
Keyword(s):  
Microwave Radiation ◽  
Transmission Lines ◽  
Biological System ◽  
Thermal Effects ◽  
Power Transmission ◽  
Power Transmission Lines ◽  
The Public ◽  
Microwave Generators ◽  
Review Reports ◽  
Power Densities

Microwave radiation is becoming more prevalent in the environment due to the increased use of radar units, guidance systems, power transmission lines, certain ovens and various appliances that use or produce radiation with frequencies between 300 and 300,000 MHz. As a result of the increased use of microwave radiation, the public is becoming more aware of microwaves and, therefore, more concerned about the risks involved in the use of microwave generators. The effects of microwave radiation on a biological system can be divided into two major groups, thermal and nonthermal. Thermal effects have received more attention and the bulk of the research to date. Most of the work discussed in this review reports on the thermal effects on biological organs exposed to various, but controlled, power densities of microwave radiation.

scholarly journals Reactive power in circuits with sampled resistive load

2017 ◽  
Vol 68 (5) ◽  
pp. 357-363
Author(s):  
Milan Stork ◽  
Daniel Mayer
Keyword(s):  
Transmission Lines ◽  
Reactive Power ◽  
Power Transmission ◽  
Active Power ◽  
Resistive Load ◽  
Time Varying ◽  
Power Transmission Lines ◽  
The Past ◽  
Voltage Drops ◽  
External Power

Abstract The process of power transmission lines, from source to load is a well-known, if the voltages and currents vary harmonically. With the lines is transmitted active power that is dissipated in load (this power exits from the system) and reactive power (this power oscillates between the source and the load). Note that it would be more appropriate designation the external power and the internal power. Such systems are known as cyclo-dissipative. The active power is dissipated in the load and the reactive power oscillates between the source and the load. Physically, reactive power is delivered to reactive elements of load. Transmitting reactive power increases Joule’s losses and voltage drops on lines. Reactive power can be compensated in a known manner. Compensation reduces the effective value of the current in the line. To the case of periodic but non-sinusoidal voltages and currents has been devoted many publications, conferences, etc. during the past 100 years. But despite much e ort, this problem has not yet been fully solved. In the present article, we show that in a system with a harmonic source of voltage even in the case of a linear pure resistive load a reactive power can be generated and can be compensated. A necessary, but not sufficient, condition is that the resistive load is time-varying. The presented study deals with a periodically sampled resistive load.

METHOD OF SYNTHESIS OF CLOSED-LOOP SYSTEMS OF ACTIVE SHIELDING MAGNETIC FIELD OF POWER TRANSMISSION LINES

2016 ◽  
Vol 2016 (4) ◽  
pp. 8-10 ◽  
Author(s):  
B.I. Kuznetsov ◽  
◽  
A.N. Turenko ◽  
T.B. Nikitina ◽  
A.V. Voloshko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Transmission Lines ◽  
Closed Loop ◽  
Power Transmission ◽  
Power Transmission Lines ◽  
Closed Loop Systems ◽  
Active Shielding

New aspects of power grid facilities personnel workplaces electromagnetic environment

2020 ◽  
Vol 60 (9) ◽  
pp. 569-574
Author(s):  
Nina B. Rubtsova ◽  
Sergey Yu. Perov ◽  
Olga V. Belaya ◽  
Tatiana A. Konshina
Keyword(s):  
Transmission Lines ◽  
Power Transmission ◽  
Power Grid ◽  
Spectral Characteristics ◽  
Ground Level ◽  
Frequency Characteristics ◽  
Frequency Range ◽  
Electromagnetic Environment ◽  
Limit Values ◽  
Special Assessment

Introduction. Electromagnetic safety of power grid facilities staff requires the exclusion of electromagnetic fields (EMF) harmful effects. EMF is evaluated by 50 Hz electric and magnetic fields (EF and MF) values in the framework of working conditions special assessment, and very rarely the analysis of the electromagnetic environment (EME) is carried out in depth. The aim of the study - EME hygienic assessment of power grid EHV facilities personnel workplace with adequate 50 Hz EF and MF levels evaluation as well as the analysis of EF and MF in the frequency range from 5 Hz to 500 Hz amplitude-frequency characteristics. Materials and methods. 50 Hz EF and MF values assessment was carried out on open switchgears (S) of substations and within sanitary breaks of 500 and 750 kV overhead power transmission lines (OTL). Measurements along to OTL trasses was performed using matrix-based method. Measurements and analysis of EF and MF values in 5-500 Hz frequency range amplitude-frequency characteristics were performed in the territory of 500 and 750 kV S. Results. Power frequency 50 Hz measurements results at 500 and 750 kV S ground-level personnel workplaces showed the presence of an excess of permissible limit values by EF intensity and the absence of an excess by MF. The measured EF values within 500 and 750 kV OTL sanitary gaps require limiting the working time of linemen due to the excess of the hygienic norms for full work shift, while the MP levels were almost completely within the standard values for persons not occupationally connected with electrical installations maintenance. MF and EE frequency range from 50 Hz to 500 Hz spectral characteristics analysis showed that 3rd harmonic percentage does not exceed 2.5% for EF and 6% for MF of the main level, the level of the 5th harmonic does not exceed 1% for EF and 3.5% for MF, the level of the 7th harmonic does not exceed 0.2% for EF and 0.8% for MF. These data show despite its low levels the contribution of MF different harmonics in a possible adverse impact on humane than EF corresponding harmonics. Conclusions. There was the confirmation of the previously justified use of the "matrix" scheme for of EF and MF values measurement along OTL routes. The relevance of to EF and MF all frequency components expos ure assessing possible health risk in extremely high voltage S territories and under OTL, based on international recommendations due to the lack of sanitary regulations in the Russian Federation for >50 Hz-30 kHz EF and MF, is shown.

Prospects for development of the Russian energy projects on the Korean Peninsula

2020 ◽  
Vol 92 (3) ◽  
pp. 8-19
Author(s):  
O.V. Demina ◽  
Keyword(s):  
Transmission Lines ◽  
Korean Peninsula ◽  
Power Transmission ◽  
Russian Far East ◽  
Far East ◽  
Primary Energy ◽  
Energy Resources ◽  
Republic Of Korea ◽  
Energy Projects ◽  
The Republic

The article assesses prospects of the Russian-Korean cooperation and analyzes risks and opportunities of the trilateral energy projects on the Korean Peninsula. The author noted that energy sector is the key area of bilateral cooperation between Russia and the Republic of Korea, but it’s mainly represented by the trade in primary energy resources. The study identified the export potential of Russian hydrocarbons to the market of the Republic of Korea. As for the DPRK, the paper shows that within bilateral relations geopolitical interests prevail over the economic ones. The small capacity of the DPRK's domestic market and the absence of fixation sources do not allow considering it as an independent full-fledged market for the Russian energy resources. The main goal of the energy strategy of Russia and the Russian Far East is increasing the volume of exports of the primary energy resources to the APR countries. Russian prospects for the new product niches in the energy markets of the Republic of Korea are associated with the implementation of trilateral energy projects among Russia, the DPRK and the Republic of Korea. It includes creation of the interstate power transmission lines and construction of a gas pipeline. All parties are interested in these projects. As for Russia, it is primarily the expansion of energy exports, including occupation of the commodity niches in new markets, and strengthening of the political role in the region. As for the Republic of Korea, these projects mean diversification of supplies and costs’ reduction of the import energy resources. And as for the DPRK, these projects imply an additional source of financing (as payment for transit), improvement of the country's energy infrastructure and reduction of the deficit of energy resources. Despite the prospects, the author determined that in the near future implementation of the projects is unlikely due to the unresolved transit risks.

scholarly journals Correction of Eddy Covariance Based Crop ET Considering the Heat Flux Source Area

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 281
Author(s):  
Stuart L. Joy ◽  
José L. Chávez
Keyword(s):  
Heat Flux ◽  
Eddy Covariance ◽  
Agricultural Land ◽  
Flux Measurement ◽  
Source Area ◽  
Mean Bias Error ◽  
Bias Error ◽  
Crop Water ◽  
The Past ◽  
Measurement Results

Eddy covariance (EC) systems are being used to measure sensible heat (H) and latent heat (LE) fluxes in order to determine crop water use or evapotranspiration (ET). The reliability of EC measurements depends on meeting certain meteorological assumptions; the most important of such are horizontal homogeneity, stationarity, and non-advective conditions. Over heterogeneous surfaces, the spatial context of the measurement must be known in order to properly interpret the magnitude of the heat flux measurement results. Over the past decades, there has been a proliferation of ‘heat flux source area’ (i.e., footprint) modeling studies, but only a few have explored the accuracy of the models over heterogeneous agricultural land. A composite ET estimate was created by using the estimated footprint weights for an EC system in the upwind corner of four fields and separate ET estimates from each of these fields. Three analytical footprint models were evaluated by comparing the composite ET to the measured ET. All three models performed consistently well, with an average mean bias error (MBE) of about −0.03 mm h−1 (−4.4%) and root mean square error (RMSE) of 0.09 mm h−1 (10.9%). The same three footprint models were then used to adjust the EC-measured ET to account for the fraction of the footprint that extended beyond the field of interest. The effectiveness of the footprint adjustment was determined by comparing the adjusted ET estimates with the lysimetric ET measurements from within the same field. This correction decreased the absolute hourly ET MBE by 8%, and the RMSE by 1%.

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