SMA Actuated Bi-Stable Electromechanical Mechanism Design for High-Current Circuit-Breaker Switching Application

PurposeIn this article we have proposed a novel design of an SMA actuated bi-stable electromechanical mechanism. The proposed mechanism can be used for several application. In this article, we have discussed the proposed mechanism from the perspective of high-current circuit-breaker switching application.MethodsThe mechanism is comprised of rigid-links, revolute joints and SMA actuator. The proposed electromechanical mechanism integratedly drives a bistable mechanical mechanism by an SMA actuator in a strategic manner. We have discussed the analysis, design and development of the proposed mechanism followed by its simulation results, prototype development and experimental investigation.ResultsAs a case study, we have constructed a prototype of such a mechanism considering some typical geometrical dimensions and values of the mechanical components. The prototyped mechanism has been experimented under 12 V, 3 A setup, which exhibits a circuit-breaking response time of around 500 ms. These quantitative values are applicable to the reported case study. Any other desired values of response time can be achieved by considering suitable geometrical dimensions and associated quantities.ConclusionThis mechanism can be used in several generic applications. Here, the proposed mechanism is exemplified by a high-current circuit-breaker switching application. We have discussed the design trade-off of the proposed SMA-actuator driven circuit-breaker mechanism through a comparison with the design of existing miniature circuit breaker (MCB) switches. The comparison exhibits the potential of the proposed device and its scope in high-current circuit-breaker switching applications. The existing mechanism uses electromagnetic principle and the proposed mechanism operates on SMA effect. This diversity in their operational physics can increase the reliability of a combined switch for the same purpose.