What does "FND" mean?

What does "FND" mean?

Question

"What does "FND" mean in the PW3360 data?

Answer

"FND" is the abbreviation for "fundamental" and it means the fundamental frequency.
"I-fnd" means the current of fundametnal frequency only.
On the other hand, "RMS" is the root mean square of 2048 sampling vallues in 200ms including the harmonic components.