Overvoltage protection circuit

Claim 1

An overvoltage protection circuit for connection between a first, reference node and a second node which is to be protected against overvoltage with respect to the first node, the protection circuit comprising: a first plurality of controllable switching elements each having a control terminal and first and second main terminals, said first plurality of switching elements being connected in series between said first and second nodes by way of a second plurality of junctions between respective first and second main terminals of adjacent ones of said first plurality of switching elements, the second plurality being equal to the first plurality minus one; biasing means connected to said first plurality of switching elements and including first and second potential divider chains each connected between said first and second nodes, the first potential divider chain having a third plurality of tapping points, the second potential divider chain having a fourth plurality of tapping points, the fourth plurality being equal to the third plurality minus one, the tapping points of the first potential divider chain being connected to corresponding control terminals of the first plurality of switching elements, the tapping points of the second potential divider chain being connected to corresponding ones of said junctions between said respective main terminals of said switching elements; and said biasing means being arranged, in the absence of an overvoltage, for biasing the first plurality of switching elements into a substantially non-conducting state, and for establishing voltages between the first and second main terminals of the respective switching elements which are within a rated value for said switching elements.