Electrical energy meter errors

[m.s.j]

A three phase and three wire energy meter has installed in a medium voltage network with a lot of third harmonic current and unbalanced load (approximately %10). As you know, any distortion in sine wave and deviation of rated frequency in AC electrical system may be cause the increasing of measuring errors.
According to a common technical practice, the third harmonic of measuring current can be trapped by using of suitable interposing current transformer with star-delta connection. This recommendation applied in above mentioned system and accuracy of measuring system improved, but the system was not disencumbered of third harmonic nuisance completely.

How can you explain the reason of nuisance continuity?

BEST REGARDS
MSJ


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[anorlunda]

Ideal devices such as transformers can do things that real life devices can't.

My guess is that saturation in the transformer core is what allows harmonics to pass.