The invention discloses a detection device and a detection method for series arc faults. The detection device comprises a
continuous current collection module, which is used for continuously collecting current at a fixed sampling rate through an A / D (Analog to Digital) converter, a
signal preprocessing module, which is used for carrying out
moving average processing on collected data, an arc fault
processing and analyzing module, which is used for computing a rate of change of current, a sum of previous N
harmonics and a
harmonic time domain waveform effective value, identifying an arc according to the three variables and giving a corresponding command, a sound-light alarm module, a drive module and a
tripping control module, which are used for deciding whether sound-light alarm is carried out and a circuit is disconnected according to the command of the arc fault
processing and analyzing module, and a communication module, which is communicated with the exterior through an RS485 interface. According to the detection device and the detection method, a
time domain and a
frequency domain are together utilized to judge whether the arc fault occurs, and through analyzing and testing, the method has the advantages of simplicity in operation, easiness in implementation, low cost and misjudgment rate and high detection probability.