Why the current in this graph is so strange?
A motor like transformers has some excitation current  that causes some &lt;10% phase lead on current with respect to voltage (not given/shown.)

But what is shown is the current of each phase with a dominant 3rd harmonic current from the non-linear core ( partial saturation at peak voltage).

By hand drawing a similar sine wave with a 3rd harmonic and adjusting the phase and amplitude, I see that the 3rd harmonic is approximately 41% of the fundamental and the phase is 1.95 radians phase lead.  Since reactance increases 300% with 3rd harmonic, we expect this for an inductor. But the core having partial saturation properties shows that the 3rd harmonic content is between 1/3 and 1/2 of the fundamental.  THis is stored energy and not contributing to work by the motor. (VAR)

The pump load will also emphasize the current harmonics and sub-harmonics if a gear ratio is involved.(not observed or analyzed) as the load is not linear throughout the pump cycle.


The fundamental above is normalized to 1 @ 0 deg phase near 50Hz with the 3rd harmonic only shown in yellow with composite waveform in red.
You can see the website where to analyze FFT and settings that I used.