Patent ID: 7791855

Claim:
A voltage surge protection device comprising at least one input for connection to an electric power supply system, at least one output for connection to an electric circuit to be protected, and voltage surge limiting means connected between the inputs and outputs for protection said electric circuit against voltage surges to the inputs, wherein the voltage surge limiting means comprise: bidirectional series electronic limiting means comprising at least two inputs/outputs series-connected with at least one of said inputs, and which are turned on when a low voltage drop occurs when a circulating current is lower than a current limiting value, and limiting said circulating current by increasing a voltage drop between said inputs/outputs, and bypass electronic limiting means connected down-line from said series electronic limiting means for limiting at least one output of protection voltage enabling the flow of interference current limited by said series electronic limiting means, said bypass electronic limiting means for protecting said electronic circuit by branching off an interference currently, wherein the series electronic limiting means comprise two series-connected field effect transistors having their reference electrodes connected to a central part, their output electrodes being connected between said inputs/outputs, and their control electrodes being connected to said central part, said current limiting value being defined by a limit value of the control voltage between the control electrodes and respective reference electrodes and internal resistances of the transistors.