Patent ID: 8724276

Claim:
A multi-stage overvoltage protection circuit, in particular for information technology systems, comprising at least one coarse-protection element and at least one fine-protection element, wherein the at least one fine-protection element can be activated by a triggering device depending on a threshold, characterized in that the present operating voltage is passed to an analyzer which generates a reference voltage from the present operating voltage, that further an evaluation unit is provided, firstly for checking whether the current operating voltage exceeds the reference voltage, secondly for checking whether the value exceedance exceeds a predetermined level in order to find out, in the third place, whether a rate of change of the operating voltage is greater than another predetermined value so that there is a transient overvoltage, wherein the triggering device receives an activation signal from the analyzer when the value exceedance exceeds the predetermined level and the rate of change of the operating voltage is greater than the another predetermined value.