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?
Now...
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?
