Transformer Life Enhancement Using Dynamic Switching of Second Harmonic Feature in IEDs

Energization of a transformer results in sudden flow of current which is an effect of core magnetization. This current will be dominated by the presence of second harmonic, which in turn is used to segregate fault and inrush current, thus guaranteeing proper operation of the relay. This additional security in the relay sometimes obstructs or delays differential protection in a specific scenario, when the 2nd harmonic content was present during a genuine fault. This kind of scenario can result in isolation of the transformer by Buchholz and pressure release valve (PRV) protection, which is acted when fault creates more damage in transformer. Such delays involve a huge impact on the insulation failure, and chances of repairing or rectifying fault of problem at site become very dismal. Sometimes this delay can cause fire in the transformer, and this situation becomes havoc for a sub-station. Such occurrences have been observed in field also when differential relay operation was delayed by 10-15 ms by second harmonic blocking in some specific conditions. These incidences have led to the need for an alternative solution to eradicate such unwarranted delay in operation in future. Modern numerical relay, called as intelligent electronic device (IED), is embedded with advanced protection features which permit higher flexibility and better provisions for tuning of protection logic and settings. Such flexibility in transformer protection IEDs, enables incorporation of alternative methods such as dynamic switching of second harmonic feature for blocking the differential protection with additional security. The analysis and precautionary measures carried out in this case, have been simulated and discussed in this paper to ensure that similar solutions can be adopted to inhibit analogous issues in future

Speciated PM10 Emission Inventory for Delhi, India

Emission inventories can serve as a basis for air quality management programs. The focus has been mainly on building inventories for criteria pollutants including particulate matter (PM). Control efforts in developing countries are mostly limited to total suspended particles (TSP) and/or PM10. Since the adverse effects of PM10 depend on its chemical composition, it is important to control emissions of toxic species. The first step is to identify key pollution sources and estimate quantities of various chemical species in emissions. This paper presents a speciated PM10 emission inventory for Delhi, the capital and one of the most polluted cities in India. An established PM10 inventory for Delhi in conjunction with source profiles was used to estimate emissions of major PM10 components including organic and elemental carbon (OC and EC, respectively), sulphates (SO42-), and nitrates (NO3-), as well as selected toxic trace metals (i.e., Pb, Ni, V, As, and Hg), some of which are subject to India&#39;s National Ambient Air Quality Standards (NAAQS). For the base year of 2007, emission estimates for PM10 mass, OC, EC, SO42-, and NO3- are 140, 22, 6.4, 2.8, and 2.1 tonnes/day (TPD; 1 tonne = 1000 kg), respectively. Emissions of Pb, Ni, V, As, and Hg are estimated to be 203, 43, 37, 26, and 9.4 kg/day, respectively. This inventory underestimated Pb and Hg emissions because sources of PM10 from unorganized secondary lead smelters are not specifically identified and gas-to-particle conversion of Hg is not accounted for.</p

A Satellite-Based High-Resolution (1-km) Ambient PM_2.5 Database for India over Two Decades (2000-2019): Applications for Air Quality Management

Fine particulate matter (PM2.5) is a major criteria pollutant affecting the environment, health and climate. In India where ground-based measurements of PM2.5 is scarce, it is important to have a long-term database at a high spatial resolution for an efficient air quality management plan. Here we develop and present a high-resolution (1-km) ambient PM2.5 database spanning two decades (2000–2019) for India. We convert aerosol optical depth from Moderate Resolution Imaging Spectroradiometer (MODIS) retrieved by Multiangle Implementation of Atmospheric Correction (MAIAC) algorithm to surface PM2.5 using a dynamic scaling factor from Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) data. The satellite-derived daily (24-h average) and annual PM2.5 show a R2 of 0.8 and 0.97 and root mean square error of 25.7 and 7.2 μg/m3, respectively against surface measurements from the Central Pollution Control Board India network. Population-weighted 20-year averaged PM2.5 over India is 57.3 μg/m3 (5–95 percentile ranges: 16.8–86.9) with a larger increase observed in the present decade (2010–2019) than in the previous decade (2000 to 2009). Poor air quality across the urban–rural transact suggests that this is a regional scale problem, a fact that is often neglected. The database is freely disseminated through a web portal ‘satellite-based application for air quality monitoring and management at a national scale’ (SAANS) for air quality management, epidemiological research and mass awareness

Semi-Crystalline, Three-Segmented Hybrid Gels with Multiple Shape-Memory Effect

24th Polymer-Networks-Group Conference / 82nd Prague Meeting on Macromolecules -- JUN 17-21, 2018 -- Prague, CZECH REPUBLIC -- Czech Acad Sci, Inst Macromolecular Chem, Polymer Networks GrpNatural biological systems such as intervertebral disk, tendon, and ligament consist of regions with distinctly different mechanical properties, yet these regions intermesh with each other through an extremely tough interface. Here the authors present mechanically strong, three-segmented hybrid hydrogels comprising of soft and hard components in a fused body resembling the mechanical heterogeneity of biological materials. An easy UV-initiated bulk copolymerization method of stratified monomer solutions is used to synthesize three-segmented hybrid hydrogels. In this method, stratification of the monomer solutions is created by means of the differences in their densities. Thus, the polymerization reactions in the monomer mixtures as well as in the interface regions occur simultaneously resulting in the formation of multi-segmented hybrid hydrogels consisting of segments with different chemical and physical properties. Hydrophilic and hydrophobic monomer mixtures compositions of stratified solutions selected in this study lead to the formation of supramolecular, semi-crystalline three-segmented hybrid hydrogels with adjustable thermal and mechanical properties. They also exhibit thermally induced pseudo multiple shape-memory function originating from distinctly different melting temperatures of crystalline domains belonging to the gel components of hybrids.Scientific and Technical Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [KBAG 114Z312]; Turkish Academy of Sciences (TUBA)Turkish Academy of SciencesThe work was supported by the Scientific and Technical Research Council of Turkey (TUBITAK), KBAG 114Z312. O. O. thanks Turkish Academy of Sciences (TUBA) for the partial support.WOS:0004742649000152-s2.0-8506706732