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Dran-View 6 User Guide

10.13. Harmonic Scaling

Harmonic

Scaling

This command will open the Harmonic Scaling dialog box.

Introduction

Harmonics may be presented in many ways. Initially they are calculated from a

voltage or current waveform signal fed into a DFT (or FFT) algorithm that

calculate the magnitudes and phase angles of each frequency component. The

magnitude is in Volts or Amps and is an “RMS” value (using the root-mean-square

formula). In Dran-View these are called “Abs” or “Absolute” values. Others may

call it “Root-Mean-Square” values. It is the same thing.

A common way to scale these values is to divide each harmonic with the

fundamental (for example 50 or 60Hz) and multiply the result with 100. This is

called %FND in Dran-View. In this case the fundamental magnitude always equals

100.0%

Another method is to divide each harmonic with the RMS-value of the signal and

multiply by 100. This is called %RMS in Dran-View.

The last method is to let the user scale the magnitude manually by a custom

number (but not 0.0). This is called %Scale in Dran-View.

Only one

scaling /

parameter is

allowed

across the

document.

Dran-View allows you to have only one type of scaling for each quantity within

the same document. This means that Phasors/DFT Charts, Harmonic Timeplots

from the instrument, and Harmonic Timeplots from the Harmonics/Timeplot

Calculator will all display Harmonics using the same scaling.

To change the settings, use the command Tools > Harmonic Scaling described in

this chapter.

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