A study on a high-reliability electromechanical undervoltage relay immersed in natural ester oil: application in mutual aid system for gensets using

The paper focuses on the reliability of an undervoltage electromechanical relay suitable for critical industrial applications. The specific application underlined in this paper is a mutual aid system for gensets: the relay is able to actuate the parallel of the batteries in case of failure of the starting-up of the genset. A particular 'Plunger-type' electromechanical device, with redundant contacts, has been proposed in order to maximize the MTBF parameter; electronics devices have been rejected in according with on-filed statistic surveys about the relative failure rates. The relay is equipped with a natural ester oil delaying system (dashpot): physical and dielectric characteristics of natural ester oil can assure better delaying system performances and insulating level. Other advantages obtainable by using insulating ester oil into the relay are also highlighted.