Abstract: The invention relates to a method, a device (10) and an arrangement (1) for monitoring alternating current electric apparatuses (3), like e.g. power distribution transformers. The inventive method relies on an inductor antenna (11, 11?) suitable to detect the electromagnetic field at the frequency of the alternating current the apparatus (3) to be monitored is supplied with arranged in the vicinity of but distant to the apparatus (3) to be monitored and comprises the steps: —Detecting the electromagnetic field radiated by the electric apparatus (3) to be monitored; —Digitizing the detected electromagnetic field to obtain EMF-data; —Running a Fast-Fourier-Transformation on the digitized EMF-data to obtain FFT-transformed data; and —Monitoring the magnitudes of the FFT-transformed data at least at the frequency of the alternating current the apparatus (3) to be monitored is supplied with and its third harmonic for anomalies.

Abstract: The invention relates to a method, a device (10) and an arrangement (1) for monitoring alternating current electric apparatuses (3), like e.g. power distribution transformers. The inventive method relies on an inductor antenna (11, 11?) suitable to detect the electromagnetic field at the frequency of the alternating current the apparatus (3) to be monitored is supplied with arranged in the vicinity of but distant to the apparatus (3) to be monitored and comprises the steps: —Detecting the electromagnetic field radiated by the electric apparatus (3) to be monitored; —Digitizing the detected electromagnetic field to obtain EMF-data; —Running a Fast-Fourier-Transformation on the digitized EMF-data to obtain FFT-transformed data; and—Monitoring the magnitudes of the FFT-transformed data at least at the frequency of the alternating current the apparatus (3) to be monitored is supplied with and its third harmonic for anomalies.