| 1. |
- Rajakaruna, Manoj, et al.
(författare)
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The behavior of Earthing Impedance and Step-Potential For Surge Currents
- 2018
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Ingår i: 2018 34th international conference on lightning protection (ICLP 2018). - New York : IEEE. - 9781538666357
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Konferensbidrag (refereegranskat)abstract
- For an effective earthing system, the resistance/impedance of the earthing system should be held at the lowest possible level. In this study, a surge generator, which can inject a 2-kV signal of 1.2/50 mu s waveform or 1 kA impulse current waveform of 8/20 mu s, was constructed to investigate the impedance of single rod earthing system. The resistivity of the soil at the selected location varies from 300 Omega m - 1700 Omega m. By using the fall of the potential method, it was observed that the impedance of single rod system varies from 900 Omega at 1 m to 70 Omega with the distance of 2-5 m. The earthing resistance of the same system was found to be 285 Omega, which is higher than the impedance.
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| 2. |
- Sapumanage, Nilantha, et al.
(författare)
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How physical attributes of transient voltages limit the efficiency of SPD array
- 2018
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Ingår i: 2018 34th international conference on lightning protection (ICLP 2018). - : IEEE. - 9781538666357
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Konferensbidrag (refereegranskat)abstract
- This study was conducted to understand what inherent limitations are associated with SPD arrays in confronting with real transient over voltages. To devise the study 403 transient voltages were selected with different physical attributes covering a range of peak-to-peak voltages, starting from 175 V up to 2861 V. The sample comprises 218 cloud-to-clouds and 185 clouds to ground generated transient voltages with mean and median values of 676.80 V and 551.00 V respectively. Impulses were segregated into three subclasses based on their physical attributes and assessed the tendency to drift through the protection array once they placed at the +90, zero and -90 phaser angles. The study revealed that 100% of positive impulses in the sample could drift through the selected array once pitched at any phaser angle on 230 V, 50 Hz utility signal. It was observed that out of the negative pulses, 90.35% at +90, 74.39 % at zero and 42.21% at -90 phaser angles, could freely move through the array. In addition to that, almost 100% of the positive portions of bipolar impulses too can reach the sensitive systems through the protection array irrespective of the pitching phaser angle.
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| 3. |
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| 4. |
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| 5. |
- Sapumanage, Nilantha, et al.
(författare)
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Insight of SPD limitations caused by incident phaser angle and physical attributes of transient voltages
- 2018
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Ingår i: 2018 34th international conference on lightning protection (ICLP 2018). - : IEEE. - 9781538666357
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Konferensbidrag (refereegranskat)abstract
- This study was devised to investigate how the pitching phaser angle and the time domain voltage profile would compel surge protective devices (SPDs) to fall short in providing guaranteed protection. The study showed that the phaser angle at which the transient voltage pitching on the 230 V power frequency signal and its time domain voltage profile play a significant role in deciding the efficiency of the protection array and the amount of incident energy that infiltrates to reach the sensitive loads connected to the low voltage power installation. The analysis managed to prove that the selected SPD array can effectively reduce the harmful energy content of the impulse to around 40% and hence it is always advantageous to have a cascaded array than a single SPD. The study emphasized that it is practically impossible to have a universal protection system that can provide the same degree of protection under all circumstances. Moreover, the study further revealed that it is rational to design a SPD array considering regional and local lightning characteristics.
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| 6. |
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| 7. |
- Sapumanage, Nilantha, et al.
(författare)
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Simulation of the surge performance of the external lightning protection system
- 2018
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Ingår i: 2018 34th international conference on lightning protection (ICLP 2018). - : IEEE. - 9781538666357
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Konferensbidrag (refereegranskat)abstract
- This paper presents an analysis done on the transient behavior of an external lightning protection system (LPS). The study was devised by modeling a Faraday's cage type LPS of a five-storied building on a MATLAB based electrical nodal network and simulating it against the 10/350 mu s lightning impulse with a peak current of 30 kA. The study focused on the down conductor material cross section area, ground impedance and the number of down conductors in the LPS to establish which factor or factors have more influence on the LPS performance. The simulation concludes that under the transient conditions the voltage dissipation on the LPS can reach several thousand volts and the peak branch current disbursements in the network are in the order of 2-2.5 kA. However, under poor ground conditions and less number of down conductors, voltage rise on the LPS system can elevate alarmingly, and branch currents tend to increase close to 7.5 kA. The study proved that the performance of the LPS and the magnitudes of the negative consequences of the associated secondary effects such as electromagnetic compatibility issues and risk associated with high step voltage issues, etc., have a close correlation with the ground impedance and the number of down conductors than that of the cross-section area of the down conductors.
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| 8. |
- Sapumanage, Nilantha, et al.
(författare)
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Study on responses of SPDs against the transient voltages generated by CG flashes
- 2018
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Konferensbidrag (refereegranskat)abstract
- This study presents the behavior of surge protecting devices (SPDs) against transient over voltages generated by cloud to ground (CG) flashes. Analysis revealed that lightning generated transient over voltages have a potential to impart detrimental effects on the SPDs. Moreover, it was concluded that comparisons between IEC laboratory impulse and the real transient voltages are remote due to factors such as peculiar time domain voltage profiles, random polarities, multiple surges with very narrow inter pulse durations in the order of microseconds. Further, observed that SPDs would not always retain within the limits specified by the manufactures under all circumstances.
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| 9. |
- Sapumanage, Nilantha, et al.
(författare)
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Time-Frequency and Energy Correlations of the Transient Voltages Triggered by Cloud to Cloud Discharges
- 2019
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Ingår i: IEEE transactions on electromagnetic compatibility (Print). - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9375 .- 1558-187X. ; 61:6, s. 1782-1792
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a study performed on time, frequency, and energy correlations of transient voltages generated by the cloud to cloud discharges. It revealed that the energy embedded in transient voltages have been lumped over few segments of time domain voltage profile than uniquely scattering over the time span. The study further determined that the energy concentration becomes higher in and around the vicinity of the time domain voltage maxima or minima, and such high energy-concentrated segments confined to a minute time span in comparison to the total time span of the transient voltage. The study also established that there is a small time lead or lag between the time domain voltage maxima or minima and the time of energy maximize. Moreover, the analysis deduced that the time lead or time lag phenomenon, is not sensitive to the orientation of the time domain voltage profile, but fuelled by the pulse type. The response time of surge protective devices can become crucial if the stipulated clamping voltages of the protection devices fall close to local peaks of the transient voltages.
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