MV vacuum switchgear based on magnetic actuators

Vacuum switchgear puts special demands on the operating mechanism, such as a large holding force and impact breaking capability. Characteristics of a permanent magnetic actuator are closer to what is required for vacuum switchgear then those of the usual spring operated mechanism. Application has advantages for simplicity, reliability and controlled switching. Tests prove these statements, for instance by switching 50000 times. Two new ideas are presented in the paper: (1) separating of the magnetic circuits for closing and opening leads to optimisation, larger forces and a more compact actuator; amd (2) application of a new designed permanent magnetic lock makes the closing characteristic to be reproduced very accurately, which can ideally be applied in the case of controlled switching. Tests confirm this feasibility