Service Support - FAQ

FAQ

Is it normal for equipment to have a Total Harmonic Distortion (THDi) of 50%~60% with light loads but drop to 5% or below with heavy loads?

The THDi equation below indicates the relation between fundamental current (I1) and harmonic current (Ih). At light load, the fundamental current (I1) is very small. When the harmonic current (Ih) is divided by a very small fundamental current (I1), it leads to an extremely large THDi. This is why the THDi indicator is not a good reference to consider for light load operations.

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