This paper addresses the problem of an actuator's load monitoring through a particular fault pattern effects
analysis. A load's failure, like a dip of torque superimposed on a constant or sinusoidal steady state load, has an effect on
the motor's supply currents. In some cases the high stress and the toxicity of the operating environment of the actuator lead
to the inaccessibility of the motor and load set and don't authorize the positioning of sensors. Consequently we use the
motor current spectral analysis for the detection of the faults that occur in the load.
To propose a global method, this paper presents an approach for the automation of the monitoring and diagnosis processes
and studies the capabilities of an easy tool, the spectrogram, to detect the apparition of the fault during the work of the
actuator and the signature obtained with different kind of faults and supplies. It also proposes a methodology to determine
the parameters of the dip of torque fault. To conclude this study, we show the validity area of the method to other king of
failure patterns.