A method for detecting an arc in a direct-current (DC) circuit comprising a DC load , a DC source supplying the DC load , and a circuit arrangement arranged between the DC source and the DC load , - wherein the circuit arrangement comprises an input comprising two input terminals (7.1, 7.2) for connecting the DC source , an output comprising two output terminals (8.1, 8.2) for connecting the DC load , and a switching unit arranged between the input and the output , - wherein the switching unit , optionally in connection with an output voltage U out applied to the output of the circuit arrangement , is designed to enable a power flow P between the DC source and the output in a first operating mode BM1 and is designed to suppress the power flow between the DC source and the output in a second operating mode BM2, comprising the method steps of: - cyclical interruption of the power flow P between the DC source and the output , in particular between the input and the output , by means of the switching unit such that the power flow P is enabled in an active time window with the first period Δt 1 and the power flow P is suppressed in an inactive time window with the second period Δt 2 , - detection of a current I characterizing the power flow P and/or a voltage U characterizing the power flow P in two consecutive active time windows , - comparing the detected values of current I and/or voltage U of the active time window with the corresponding detected values from the preceding active time window , and - signaling of an arc if the values of current I and/or voltage U of the active time window differ from the corresponding values of the preceding active time window by more than a threshold value. - wherein the circuit arrangement comprises an input comprising two input terminals (7.1, 7.2) for connecting the DC source , an output comprising two output terminals (8.1, 8.2) for connecting the DC load , and a switching unit arranged between the input and the output , - wherein the switching unit , optionally in connection with an output voltage U out applied to the output of the circuit arrangement , is designed to enable a power flow P between the DC source and the output in a first operating mode BM1 and is designed to suppress the power flow between the DC source and the output in a second operating mode BM2, - cyclical interruption of the power flow P between the DC source and the output , in particular between the input and the output , by means of the switching unit such that the power flow P is enabled in an active time window with the first period Δt 1 and the power flow P is suppressed in an inactive time window with the second period Δt 2 , - detection of a current I characterizing the power flow P and/or a voltage U characterizing the power flow P in two consecutive active time windows , - comparing the detected values of current I and/or voltage U of the active time window with the corresponding detected values from the preceding active time window , and - signaling of an arc if the values of current I and/or voltage U of the active time window differ from the corresponding values of the preceding active time window by more than a threshold value. <EOS>