One of the major challenges of DC circuit breakers is the required fast mechanical actuator. In this paper, a Thomson coil actuator system for a vacuum interrupter is designed. Active damping is used to decelerate the moving contacts. Challenges are discussed, especially concerning the power supply needed for the Thomson coil actuator. The design philosophy is explained and FEM simulation results are presented. The results indicate that a wide range of combinations of drive circuit capacitance and voltage fulfill the requirements for armature acceleration. However, active damping requires a very careful selection of drive circuit voltage and timing of applied damping.
Wind farms are an important part of renewable energy system but they are frequently damaged by lightning strikes, especially to the blades of the turbine. Recent field observations have shown lightning damages several meters inboard away from the blade tip, which cannot be explained fully by the interception of stepped leaders or swept strokes. This paper proposes a possible additional mechanism to explain the lightning attachment points in inboard area of blade due to dart lightning leaders. This mechanism is verified through the Self consistent Leader Inception and Propagation Model -SLIM which is used here to dynamically evaluate the upward connecting leader propagation under the influence of both stepped and dart leaders.
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