Faculty Publications
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Item E-field computation in 765 kV substation using CSM with reference to occupational exposure(Institution of Engineering and Technology journals@theiet.org, 2018) Devarajan, D.; Punekar, G.S.; Bhatt, N.S.With the increase in transmission voltage level, and the guidelines of the International Commission on Non-Ionising Radiation Protection (ICNIRP), the effects of non-ionising radiation on biological elements at high-voltage substations have gained significant importance. The electric field (E-field) distribution in an upcoming 765 kV substation in the Indian subcontinent is computed using the charge simulation method (CSM). CSM is used to model the 765 kV bays, transmission lines, buses, and ground wires in the substation. The three-dimensional (3D) E-field is calculated through the superimposition of E-fields obtained in two orthogonal planes using infinite-line charges. This proposed method of using infinite-line charges gives realistic results. The simplistic model using infinite-line charges greatly reduces the complexity of the CSM-based model (due to the reduced number of charges) apart from increasing the CSM-based model accuracies. This fact has been demonstrated by comparing these results with those of CSM-3D-model of a detailed bay model (including major equipment and associated support structures). The complex-charge-based CSM helps in computing the root mean square value of the E-field at a point, directly, as per ICNIRP guidelines. This RMS value of the E-field is compared with the occupational exposure reference value prescribed in the ICNIRP guidelines. © The Institution of Engineering and Technology 2017.Item An experimental study on rock damage and its influence in rock stress memory in a metamorphic rock(Springer, 2020) Srinivasan, V.; Gupta, T.; Ansari, T.A.; Singh, T.N.Rock stress memory, often referred as Kaiser effect, in rocks can be an effective tool to estimate the in situ stress conditions, if the uncertainties in rock damage and its behavior during loading conditions are properly understood. In view of this, the present study is an attempt to investigate the variations in rock stress memory, i.e., the Kaiser effect in a metamorphic rock under multi-stage uniaxial compression. The khondalite rock samples from Eastern Ghats Mobile Belt (EGMB) belonging to southeastern part of Indian subcontinent having complex geological history are examined. The effects of multi-stage compression on the damage evolution and subsequent variations in rock stress memory are investigated. The samples were categorized into different levels of rock stress memory, depending on the stress the rock was able to withhold after loading stages. The damage evolution in the tested rocks was predominantly controlled either by initial loading or failure stress. Higher damage imparted by initial loading and intense fracturing could be the possible reason for poor stress memory function in the investigated rock. Felicity ratio, an indicative of rock damage with stages of loading, supported the observation that rock damage was dominant during initial loading stage. Rock heterogeneity has played a dominant role in decay of Kaiser effect, with intense fracturing during subsequent loading stages in the investigated rocks. To summarize, Kaiser effect can be used to infer rock damage and stress conditions, provided the geological history of the region is also taken into consideration. With rocks from complex geological conditions, Kaiser effect or rock stress memory should be supported by other tools to infer in situ stress, but the method can be effectively used to understand the stress changes and damage mechanism of multiple loading. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.