A tracker for an electrical machine supplied by an alternating supply voltage on at least one phase, including: - means for measuring an alternating supply voltage, characterised in that it includes - means for detecting an electrical transient as a function of the measurements performed, the means for detecting an electrical transient being adapted to: - acquire voltage measurement samples during at least two successive voltage cycles, - store the measurement samples acquired, - calculate the voltage differences between the measurement samples acquired for the at least two successive cycles, - compare the differences calculated with a predetermined threshold, - detect an electrical transient if a difference is greater than the predetermined threshold, - means for characterising the electrical transient detected, to determine a set of parameters of the electrical transient, including at least one parameter selected from the amplitude of the electrical transient and the position of the electrical transient in the voltage cycle, - means for validating the electrical transient implementing at least one validation criterion selected from the validation of an electrical transient if its amplitude exceeds an amplitude threshold and the validation of an electrical transient if the position of the electrical transient is at least partly in one of zones defined about the voltage maxima, in order to identify whether an electrical transient affects the electrical machine. - means for measuring an alternating supply voltage, - means for detecting an electrical transient as a function of the measurements performed, the means for detecting an electrical transient being adapted to: - acquire voltage measurement samples during at least two successive voltage cycles, - store the measurement samples acquired, - calculate the voltage differences between the measurement samples acquired for the at least two successive cycles, - compare the differences calculated with a predetermined threshold, - detect an electrical transient if a difference is greater than the predetermined threshold, - acquire voltage measurement samples during at least two successive voltage cycles, - store the measurement samples acquired, - calculate the voltage differences between the measurement samples acquired for the at least two successive cycles, - compare the differences calculated with a predetermined threshold, - detect an electrical transient if a difference is greater than the predetermined threshold, - means for characterising the electrical transient detected, to determine a set of parameters of the electrical transient, including at least one parameter selected from the amplitude of the electrical transient and the position of the electrical transient in the voltage cycle, - means for validating the electrical transient implementing at least one validation criterion selected from the validation of an electrical transient if its amplitude exceeds an amplitude threshold and the validation of an electrical transient if the position of the electrical transient is at least partly in one of zones defined about the voltage maxima, in order to identify whether an electrical transient affects the electrical machine. <EOS>