Three-phase unbalance refers to the inconsistency of the three-phase current (or voltage) amplitudes in the power system, and the amplitude difference exceeds the specified range.

The harmonic protector is a new type of protection device used to filter out high-order harmonics and protect precision instruments and equipment. It adopts ultra-microcrystalline alloy materials and innovative special circuits. It is mainly composed of voltage clamps, low-pass filters and absorbers.