An arc fault detector includes: a first electric line; a sensor for monitoring an electric current or voltage spectrum in the first electric line and outputting a broadband measurement signal as a monitored signal; a minimum detection unit for detecting a minimum signal value of the monitored signal over a broadband measurement range as a detected minimum signal value; and a controller unit connected to an output of the minimum detection unit, the controller unit comparing the detected minimum signal value with a predefined arc pattern, and outputting a trigger signal on a trigger output if the detected minimum signal value matches the arc pattern.