ACTIVE LIGHTNING PROTECTION

摘要

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. The thyristor is arranged to start conducting when the input voltage reaches a predetermined level, thereby discharging the capacitor through the thyristor to ground and creating a pulse on the primary side of the transformer. This pulse is then transformed into the trigger signal by the transformer.