Electromagnetic actuators for medium voltage vacuum switching devices: Classification, design, controlling

Vacuum switching devices (circuit breakers and contactors) dominate the current market of medium voltage devices. In the paper a classification of electromagnets and actuators which are used in MV vacuum switching devices is presented. Peculiarities, advantages and disadvantages of bistable and monostable electromagnets and actuators are analyzed. Information on the developments of the authors as well as the results of theoretical and experimental investigations of new designs of polarized monostable electromagnet actuators are presented and analyzed. Relevant microprocessor controlling devices and methods of switching windings allowing to create effective designs of MV vacuum switching devices are described. The results of investigations have been tested on several prototypes of circuit breakers and contactors which were presented at various exhibitions. The proposed solutions on the design of bistable actuators with monostable polarized electromagnets, ways to control windings of such electromagnets as well as varistor degaussing of windings at their disconnection by transistor switches are tested experimentally on single prototypes and worth discussing the possibility of their industrial application after the full-scale tests on a sufficient number of vacuum contactors and circuit breakers.