Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
5 results
Search Results
Item Spatiotemporal electric field distribution in an EHV substation in view of occupational exposure(Institute of Electrical and Electronics Engineers Inc., 2019) Devarajan, D.; Punekar, G.S.; Kishore, N.K.With the increase in the transmission voltage levels, the effect of non-ionizing radiation (NIR) becomes a major concern. The International Commission on Non-Ionizing Radiation (ICNIRP) provides the guidelines for protection against NIR. It suggests the reference electric field (e-field) value of 10 kV/m for occupational exposure and 5 kV/m for general public exposure for the substation. In view of this, e-field prevailing in a 765 kV generating substation is studied in the present work to assess the spatiotemporal distribution using charge simulation method (CSM) based model. This should give a feel of the possible threat posed by these fields to the working personal due to NIR. The upcoming EHV substation in central India is considered with its bays, transmission lines, buses, and ground wires. The instantaneous values of e-field are computed at different instances over the 50 Hz voltage cycle, at 2 m height above the ground plane over the entire substation arena. The demo of spatiotemporal variation of e-field computed at different instants of time over a cycle using simulating charges taken from the real-number-field will be presented and discussed during the presentation. This would result in a time-space changing e-field-force, and give a feel of creation of churning of air and electric wind. This will have much higher significance at the heights were conductors are placed where the e-fields are higher. It is also shown that because of spatiotemporal variation of e-field, the rms value of e-field can be easily obtained using simulating charges taken from complex-number-field which is of significance from the point of view of ICNIRP guidelines. © 2019 IEEE.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 Musculoskeletal Disorders Among Dozer Operators Exposed to Whole-Body Vibration in Indian Surface Coal Mines(Springer, 2020) Jeripotula, S.K.; Mangalpady, A.; Raj, G.R.Dozer operators are frequently exposed to whole-body vibration (WBV) during the execution of their work. Occupational exposure to WBV in Indian surface coal mines was evaluated by measuring vibration intensity and duration of exposure. A triaxial accelerometer was placed on the operator seat surface for taking the readings. Based on frequency-weighted root mean square acceleration equivalent to 8-hr shift duration, i.e., (A(8)) all dozer operators have exceeded an Exposure Action Value (EAV) of 0.5 m/s2, and 90% of dozers did not exceed Exposure Limit Value (ELV) of 1.15 m/s2. Based on Vibration Dose Value (VDV (8)), all dozer operators have exceeded Exposure Limit Value (EAV) of 9.1 m/s1.75, but no dozer operators have exceeded Exposure Limit Value (ELV) of 21 m/s1.75. Further, an epidemiological study was performed for identifying the extent of musculoskeletal disorders (MSDs) among dozer operators. For the detailed study, 42 dozer operators and 22 controls were selected from 2 surface coal mines. The control group was not exposed to WBV. It was seen from the cross-sectional study that pain in the lower back was predominantly higher (83.33%) in the exposed group when compared with the control group (31.81%). Likewise, pain in the neck (47.61%), shoulder (42.85%), knees (42.85%), and ankle (11.90%) was higher in the exposed group than that of the control group (22.71%, 0%, 45.45%, and 4.54%). A significant observation among the exposed group was that there was degradation in the quality of life. The outcome of the study would assist in monitoring and mitigation of machinery-induced vibration diseases (MIVD) in India and generally applicable to most of the mechanized mines as well. However, comprehensive studies are still needed to enunciate the magnitude extent. © 2020, Society for Mining, Metallurgy & Exploration Inc.Item Ergonomic Assessment of Musculoskeletal Disorders Among Surface Mine Workers in India(Springer Science and Business Media Deutschland GmbH, 2021) Jeripotula, S.K.; Mangalpady, M.; Raj, G.R.Injuries due to work-related musculoskeletal disorders (WMSDs) are not uncommon in heavy industry like mining. Researchers acknowledged that occupational exposure to ergonomic risk factors is the chief causative factor in the development of WMSDs. The aim of this study was to perform an ergonomic assessment of musculoskeletal disorders among surface mine workers in India. Standardized Nordic Questionnaire was used to collect subjective response from 500 workers. A stratified random sampling method according to surface mining work activity type was used to obtain the sample. Data was collected by means of a structured questionnaire, and the Statistical Package for Social Sciences (SPSS) was used to analyze data using descriptive and inferential statistical methods. A response rate of 85% was obtained out of 500 targeted groups. The WMSDs prevalence for the 12-month period was estimated to be 44.23%. The mean and standard deviation of workers’ age were 41.31and 8.927, respectively. The study has shown that the operators of dumpers, dozers, and graders along with electricians were found to be the most susceptible to develop WMSD problems. Among the most affected body parts, back disorder reported the highest. Further, it was found that working with static posture over the longer duration has a significant association with the lower back disorder (with p = 0.020) and bouncing and jarring has also significantly associated with the lower back disorder (with p = 0.023). Similarly, a significant association was found between repetitive work and neck pain (with p = 0.016). The study depicted a significant association between ergonomic hazards and WMSDs, like working with prolonged static posture, bouncing and jarring, and repetitive work. © 2020, Society for Mining, Metallurgy & Exploration Inc.Item GA-CSM based optimized clearances for the reduction of occupational exposure in EHV substation☆(Elsevier Ltd, 2023) Devarajan, D.; Punekar, G.S.The magnitude of the electric field (E-field) in a 765 kV substation is reduced by altering the conductor clearances in view of the occupational exposure limits. Multi-objective genetic algorithm (GA) along with the charge simulation method (CSM) is utilized in arriving at the optimal clearances of the substation conductors. An EHV substation is modeled with the dimensions and the clearances as in the actual layout of a substation. The E-field results obtained using the finite-line based modeling and infinite-line based modeling of conductors, are compared in terms of the model accuracy and the computational time. The advantages of using the infinite-line based CSM model in view of the occupational exposure is detailed. With the proposed GA-CSM routine, the maximum value of the E-field in the substation is reduced to 10 kV/m (from the existing value of 13 kV/m). The proposed method is used with the existing topology and the best possible transposed topology to obtain the modified layouts. A novel EHV substation layout with different ground clearances for the inner bays and the outer bays is presented. The GA-CSM routine proposed in this work is applicable to any EHV substation with the multiple conductor arrangements. © 2022