Faculty Publications
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Item E-fields inside 765 kV substation: Influence of conductor & bay arrangements(Institute of Electrical and Electronics Engineers Inc., 2017) Singh, S.K.; Punekar, G.S.Increasing voltage level in generation and transmission system have become inevitable. The threats of non-ionizing radiation and their biological effects at substations have increased. As per International Commission for Non-Ionizing Radiation and Protection (ICNIRP) guidelines suggest maximum limits for electric and magnetic field exposure is 10 kV/m and 1 mT for occupational and 5 kV/m and 250 μT for public exposure. Keeping this in view results of a case study of electric field distribution in an upcoming 765 kV substation in India are computed and discussed in this paper. Using the existing layout of this substation, the E-fields at 2 m height above the ground plane are computed using FEMM (a free ware). Results show that Bays which are at a height of 14 m from ground are dominant and contributing more to the E-fields. The paper further computes and compares E-field strength due to (i) a single conductor (a phase of bay alone), (ii) single bay (iii) and with all the bays of substation with buses, overhead headlines and ground wires. The effect of bay height (around 14 m) on the E-field is also reported. The average E-field in substation arena is well within the ICNIPR suggested limit of 10 kV/m, whereas E-field at some places exceeds this value. © 2016 IEEE.Item Electric Fields due to A 500 kV Quadruple Circuit Transmission Line: Some Aspects Concerning Public Exposure(Institute of Electrical and Electronics Engineers Inc., 2019) Prasad, K.Y.; Punekar, G.S.Extra high voltage and Ultra high voltage transmission lines produce high intensity electric fields (E-fields). These high intensity E-fields, which are in the vicinity of such lines, would result into adverse effects on humans. E-fields at the ground level should be below a certain limit as specified by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines from the point of view of public exposure. In the present study the E-fields due to the Quadruple circuit transmission line is estimated and analyzed. Finite element method is used to calculate the E-fields by placing the conductors at the permitted worst-case sag (8%) position for the chosen span. These results are compared with those available in the literature with 4 % sag. © 2019 IEEE.Item Design and experimental characterization of a twin-tube MR damper for a passenger van(Springer Verlag service@springer.de, 2019) Desai, R.M.; Jamadar, M.E.H.; Kumar, H.; Joladarashi, S.; Raja Sekaran, S.C.The smart behavior of magneto-rheological (MR) fluid is used in the present work in designing, experimentally characterizing and analyzing a MR damper for automotive application using the twin-tube damper concept. A commercially available passive damper of a passenger van was tested to find the characteristic damping requirement of the vehicle. With this as reference, a twin-tube MR damper working in valve mode was designed and fabricated. The magnetic flux density induced in the fluid flow gap is maximized using Taguchi analysis and finite element method magnetics (FEMM) software. The FEMM results are validated by verifying with results obtained analytically using electromagnetic circuit theory. The MR damper filled with commercially available MR fluid was experimentally tested in damper testing machine. The results demonstrate that the force developed by the MR damper is indeed increasing with the value of the current supplied. At various frequencies of input oscillation, the energy dissipated by the MR damper in a single cycle increases significantly with current supplied. The novelty of this work is that a twin-tube MR damper working in valve mode was designed as a replacement for the passive damper used in a passenger van. The MR damper thus developed is capable of producing practical levels of damping force at actual operating frequencies and amplitudes of the passive damper in the passenger van. For further analysis, the behavior of the MR damper is modeled by using the Bouc–Wen model for hysteretic systems. A proportional–integral–derivative controller is used to track the desired damping force in time domain to demonstrate the application of the MR damper in a semi-active suspension system. © 2019, The Brazilian Society of Mechanical Sciences and Engineering.Item Performance Evaluation of Magneto-Rheological Damper Through Characterization Testing, Modeling and its Implementation in Quarter Car(Springer, 2022) Puneet, N.P.; Devikiran, P.; Kumar, H.; Gangadharan, K.V.Purpose: Semi-active devices are showing a greater prominence in several engineering applications in recent times. This work makes an attempt to evaluate the performance of semi-active damper when used with a class of smart material called magneto-rheological (MR) fluid. Method: Initially an MR damper is developed and characterized using an in-house prepared MR fluid. The rheological study is also performed for the prepared MR fluid at different input currents. The behavior of the MR damper through characterization testing is modeled using a hysteretic modeling technique known as Kwok model and the parameters are converted into current-dependent variables. The force simulation through Kwok model is used in quarter car simulation model for different dynamic conditions with off-state, constant current and current through Skyhook control. Results: The comparative results with different current conditions are analyzed. An attempt has been made to replicate these conditions in the experiments using quarter car test rig. Conclusion: Both simulation and experimental analyses revealed greater vibration suppression capability of MR damper when used with skyhook control. On an average, 24% peak amplitude reduction is observed when compared to off-state condition. © 2021, Krishtel eMaging Solutions Private Limited.Item Effect of reduced geometric dimensions on torque generation in two plate rotor magnetorheological brake with in-house magnetorheological fluid(Institute of Physics, 2023) Kariganaur, A.K.; Kadam, S.; Kumar, H.; Arun, M.The present study is aimed to evaluate the torque generation capacity of a two plate rotor magnetorheological (MR) brake using in-house prepared MR fluid. The prepared MR fluids were studied for sedimentation rate at different temperatures and flow characterization at different currents and at specific temperatures. The yield stress of the fluid is explored through Herschel-Bulkley model. The results depict significant increase in sedimentation rate and decrease in yield stress with increase in temperature of the MR fluid. MR brake (model-1) is fabricated after finite element method magnetics exhibit magnetic field of approximately 0.145 T in the shear gap than other two models (model-2 and model-3) considered in this study. Characterization of the MR brake illustrates that there is an increase in torque with increasing current. Further tests have been carried out to identify the effect of sedimentation on torque generation at 52 °C after 15 h of sedimentation. The results indicate 16% reduction in the initial torque because of settling of particles. MR fluid and particles characterization illustrates that 322 °C and 400 °C are critical points in controlling the MR fluid input parameters. © 2023 IOP Publishing Ltd.Item Cable dimension determination using Finite Element Method Magnetic (FEMM) for three-core belted and gas insulated cables(Elsevier Ltd, 2024) Tefera, T.N.; Punekar, G.S.; Ibrahim, K.; Tuka, M.B.; Bajaj, M.A numerical approach utilizing the Finite Element Method (FEM) based freeware Finite Element Method Magnetic (FEMM) is employed to optimize the insulation thickness to diameter ratio (‘T/d’) for a three-core belted cable, enclosed by a grounded sheath, as well as for a gas-insulated cable (GIC) with a common enclosure. The method analyzes the maximum electric field (E-field) within the cable. The minimum E-field magnitude across three critical regions where the E-field at its peak is calculated for different ‘T/d’ ratios, and the optimal ‘T/d’ is identified by selecting the maximum of these minimum values. Analogs to single-core coaxial cable, for a three-core belted cable with a radius of 1 per unit (p.u.), the best ‘T/d’ ratio is 0.80 when subjected to a 1 p.u. Peak potential. Additionally, the optimal conductor radius and conductor-to-cable center dimension for common-enclosure gas-insulated cables are verified to be 0.18 and 0.5, respectively. This study provides a first-time investigation of the best ‘T/d’ ratio for three-core belted cables and verifies CGIC cable parameters using FEMM, where no analytical solutions are available. The results are validated by comparing FEMM with analytical and Charge Simulation Method (CSM) outcomes. Hence, the FEMM provides low computational cost and reliable results compared to commercial software. Through these simulation efforts, the study re-examines the stress within the belted and gas-insulated cables and the parameters that influence it. The FEMM method allows for precise control of both conductor and sheath potentials, ensuring no potential discrepancies between the applied and calculated values across the entire range of T/d ratios. © 2024 The Author(s)