Abstract: An apparatus for detecting direct current magnetic flux deflection of an electrical transformer comprising a magnetic detector for generating an output voltage waveform and Fourier series developer connected to the magnetic detector for developing the output voltage waveform from the magnetic detector into a Fourier series. An even number harmonic detector is connected to the Fourier series developer for detecting an even number harmonic in the Fourier series, thereby determining the presence of a direct current magnetic flux deflection. A process for detecting direct current magnetic flux deflection is also disclosed.