Abstract: An improved device for over-voltage protection is disclosed. A triggerable three electrode GDT (Gas Discharge Tube) is in the device used for discharging voltage. The GDT is connected between an input of the device and ground, and has its trigger electrode connected to a secondary side of a transformer. The transformer is arranged for producing a trigger signal in response to a voltage on the input for triggering said GDT into a conducting state. According to the present invention, a primary side of the transformer is connected to the input via a capacitor and a resistance, wherein a current flowing from the input through said resistance charges said capacitor when the voltage on the input increases. A thyristor is connected to ground, from a point between the resistance and the capacitor.

Abstract: An improved device for over-voltage protection is disclosed. A triggerable three electrode GDT (Gas Discharge Tube) is in the device used for discharging voltage. The GDT is connected between an input of the device and ground, and has its trigger electrode connected to a secondary side of a transformer. The transformer is arranged for producing a trigger signal in response to a voltage on the input for triggering said GDT into a conducting state. According to the present invention, a primary side of the transformer is connected to the input via a capacitor and a resistance, wherein a current flowing from the input through said resistance charges said capacitor when the voltage on the input increases. A thyristor is connected to ground, from a point between the resistance and the capacitor.

Abstract: An over-voltage protection arrangement (1) for protecting an electric device from over-voltages, the arrangement comprising an input voltage terminal (2), to be connected to a voltage feed, and an output voltage terminal (3), to be connected to the electric device to be protected, whereby the arrangement (1) is adapted to protect the electric device from voltages on the voltage feed deviating from a predefined threshold range, the arrangement further comprising a field effect transistor (4) connected in between the input terminal (2) and the output terminal (3) so as to enable an electric connection between said terminals (2, 3). The arrangement (1) is distinguished by: at least one trigger circuit (6a, 6b) being adapted to respond to a trigger voltage, a voltage on the voltage feed deviating from the threshold range, by controlling the field effect transistor (4) to throttle the electric connection between the input (2) and output (3) terminals.