Triplen Harmonic

What is a Triplen Harmonic and why is it dangerous?

It is the distortion of the sine wave in a 3-phase power distribution system, but has a frequency multiple of 3. This current harmonic can overheat neutral lines.

How to calculate the Triplen Harmonic?

The Triplen Harmonic is the 3rd, 6th, 9th fundamental frequency of the system, caused by non-linear components (diodes, transisters, etc).

The formula for the Nth harmonic is

Van= E*cos n(wt+0º)

Vbn= E*cos n(wt+120º)

Vcn= E*cos n(wt-120º)

Normally this does not create a problem in the neutral line since everything cancels out.

But in the 3rd harmonic looks like:

Van = E*cos 3(wt+0º)

Vbn = E*cos (3wt+360º)

Vcn = E*cost (3wt-360º)

This could create a problem because now the neutral line is taking all the current for all the branches at the same time.

Possible fix:

Use Delta Transformers, eliminating the neutral current.

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