A device , having: an input signal interface for receiving a digital measurement signal, containing a sequence of samples, that represents a signal detected at a connection point of electrical equipment , and a processor unit , wherein the processor unit is configured to assign each sample of the measurement signal a respective signal window formed from a respective portion of the sequence of samples of the measurement signal containing the respective sample and a predetermined number of temporally preceding samples of the measurement signal; wherein the processor unit is configured so as, in an initialization phase , to determine a number of M signal windows as initialization windows and from these M initialization windows a number of K noise windows, to analyze each noise window by means of a predetermined Xth-order model and to ascertain the associated coefficients that form an initial coefficient tuple assigned to the respective noise window, and to ascertain an expected value as a noise tuple from the initial coefficient tuples of the noise windows, X being an even number between one and five; and wherein the processor unit is configured so as, in an examination phase , to determine a plurality of the signal windows as measurement windows, to analyze each measurement window by means of the predetermined Xth-order model and to ascertain the associated coefficients that form a measurement tuple assigned to the respective measurement window, to ascertain a distance of the associated measurement tuple from the noise tuple for each measurement window, and to determine from the plurality of measurement windows the measurement windows whose associated measurement tuple is at a respective distance from the noise tuple that is greater than a first, predetermined limit value G as error signal windows, with the result that each error signal window represents a signal error of the measurement signal. an input signal interface for receiving a digital measurement signal, containing a sequence of samples, that represents a signal detected at a connection point of electrical equipment , and a processor unit , wherein the processor unit is configured to assign each sample of the measurement signal a respective signal window formed from a respective portion of the sequence of samples of the measurement signal containing the respective sample and a predetermined number of temporally preceding samples of the measurement signal; wherein the processor unit is configured so as, in an initialization phase , to determine a number of M signal windows as initialization windows and from these M initialization windows a number of K noise windows, to analyze each noise window by means of a predetermined Xth-order model and to ascertain the associated coefficients that form an initial coefficient tuple assigned to the respective noise window, and to ascertain an expected value as a noise tuple from the initial coefficient tuples of the noise windows, X being an even number between one and five; and wherein the processor unit is configured so as, in an examination phase , to determine a plurality of the signal windows as measurement windows, to analyze each measurement window by means of the predetermined Xth-order model and to ascertain the associated coefficients that form a measurement tuple assigned to the respective measurement window, to ascertain a distance of the associated measurement tuple from the noise tuple for each measurement window, and to determine from the plurality of measurement windows the measurement windows whose associated measurement tuple is at a respective distance from the noise tuple that is greater than a first, predetermined limit value G as error signal windows, with the result that each error signal window represents a signal error of the measurement signal. <EOS>