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Harmonics & True RMS


Lehman Engineering Power Quiz
"Harmonics And True RMS"

Consider a non linear load which is being fed from a transformer. The load draws a current that has a 60 Hz fundamental component of 10 Amps RMS and has a 3rd order harmonic (180 Hz) component of 5 Amps RMS.

Question #1:
What is the total RMS value of the current that would be read on a True RMS meter?

Question #2:
What is the Total Harmonic Distortion (THD) of the current?

Assume the load current has a 10A RMS, 60 Hz fundamental component as in the original problem, BUT the 3rd order harmonic is now changed to a 5th order harmonic with the same 5A RMS value.

Question #3:
Does the total RMS value of the current change due to the higher frequency of the 5th harmonic?

Question #4:
Will the THD of the load current remain the same, increase or decrease?

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