Optimal design of autorecloser electromagnetic actuator

Following the successful development of a bistable electromagnetic switchgear actuator for driving vacuum interrupters in an autorecloser, several MV switchgear companies have begun to develop similar actuators for use in autoreclosers powered by primary lithium batteries. However, many of these actuators consume excessive energy in operation, adding undesirable battery cost to the equipment. A model is developed that enables these actuators to be optimised in energy terms, since it simulates the electrical, magnetic and mechanical effects seen by the actuator and their interactions. The model is a detailed lumped reluctance type. The lumped reluctances were defined after inspecting the results of the finite element analysis of a generic actuator. The model uses iteration routines to calculate the flux distribution within it and an improved stochastic optimal method to obtain an optimal design, in terms of magnet cost and operating energy usage. Simulated and test results are presented, and these show a close correlation.