Hazemeijer B.v.

Bertus Griesen

Harry C Gundlach

A method for interrupting an inductive load in a three-phase, high voltage network by means of a switch having a quick dielectric recovery, in particular a vacuum switch, in which two of the three vacuum switches, having a quick dielectric recovery, open at least 1/3 of a cycle of the network frequency later than the first vacuum switch, augmented with the minimum arcing time in the first vacuum switch, in order to prevent high over-voltages, caused by virtual chopping.

Method for switching in a three-phase high voltage circuit

A high tension vacuum switch, comprising two relatively axially movable switching contacts and two annular electrodes for shielding the open contacts from excessive electric field, in which each shield is associated and electrically coupled with a respective one of said switching contacts and projects slightly beyond the contact surface of said contact in the direction towards the other switching contact to provide the field-shielding effect when the contacts are open. At least one of the shielding electrodes is not directly connected electrically but is only capacitively coupled with its respective switching contact so as to add the advantage of much smaller overall dimensions for a switch of this kind.

High tension vacuum switches

Electrical vacuum switch having two contact members carried by contact rods for moving the contact members in and out of engagement with each other, in which each contact rod is partly surrounded by a yoke of magnetic permeable material, closely adjacent each contact member, each yoke leaving a gap between the yoke legs, so that upon moving the contact members out of engagement, the magnetic flux lines, generated in each yoke by the current through the contact rods, will traverse the arcing gap between the contact members, towards the opposing yoke, resulting in a magnetic field in the arcing gap.

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Hengelo, Netherlands

Bertus Griesen