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ABSTRACT: Arresters connected in parallel with distribution transformers limit lightning caused over-voltage to the residual voltage which due to long duration lightning strikes, may cause magnetic saturation of the transformer core. This, in turn, leads to transient currents which may cause nuisance operation of fuses. In this paper the influence on current, voltage and transient of lightning current amplitude, duration and the phase angle of the AC voltage at the moment of lighting strike has been simulated. The simulation results indicate that a long duration lightning current, even with low amplitude, may cause transformer core saturation and inrush current. The simulation results may be helpful in the assessment of lightning performance of operating transformers and arresters and the design of suitable schemes to minimize nuisance fuse operation and the specification of guidelines for fuse selection and arrester ratings.
Electrical Insulation and Dielectric Phenomena, 2005. CEIDP '05. 2005 Annual Report Conference on; 11/2005
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ABSTRACT: Assessment of damage due to direct lightning strikes on underground cables is important in the design of protection schemes and mitigating strategies. Existing models do not adequately account for the influence of formation of breakdown channels in the soil. In the paper, a two-dimensional model based on electric-field-related probabilities is proposed to predict the formation of breakdown channels and their effect on ground resistance. The influence of lightning current amplitude, geometric configuration and soil parameters has been considered. The model provides a means for complete assessment of the lightning performance of underground cables.
IEE Proceedings - Generation Transmission and Distribution 10/2003; · 0.48 Impact Factor
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ABSTRACT: A lightning strike is known to result in the formation of breakdown channels in ground that may be intercepted by buried cables in the vicinity of the strike point, with attendant consequences. Modelling this phenomenon is important in order to be able to devise protective and mitigating strategies. Existing models do not adequately take into account breakdown channel formation in ground and ignore soil nonhomogeneity. The authors present a representative two-dimensional model that accounts for the random growth of channels in two-layered nonhomogeneous soils governed by the local electric field strength. The influence of lightning current magnitude, geometric configuration, and soil parameters is considered. The suggested model provides a means for complete assessment of the lightning performance of underground cables.
International Journal of Modelling and Simulation 28(1):27-34.
