Schneider Electric PM5300 Manual De Usuario

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Chapter 11—Power quality

PowerLogic™  PM5300 series user guide

The meter supports two methods of calculating total harmonic distortion: THD and thd.

 is a quick measure of the total distortion present in a waveform and is the ratio of 

harmonic content to the fundamental. The meter uses the following equation to 
calculate THD:

Where H1 is equal to the fundamental harmonic.

 is an alternate method for calculating total harmonic distortion. It uses the RMS 

value for the total harmonic content rather than the fundamental content. The meter 
uses the following equation to calculate thd:

(total demand distortion) evaluates the harmonic currents between an end user 

and a power source. The harmonic values are based on a point of common coupling 
(PCC), which is a common point where each user receives power from the power 
source. The meter uses the following equation to calculate TDD:

Where ILoad is equal to the maximum demand load on the power system.

The meter displays the numeric magnitude and angle of the fundamental (first) 
harmonic.

You can view harmonics data using the front panel.

1. Navigate to Harm. The Harmonics % screen displays, with the following menu 

options:

2. Press the voltage or current harmonics you want to view. The fundamental (1st) 

harmonic’s numeric magnitudes and angles for all phases are displayed.

3. Press 3-11, 13-21, or 23-31 to view the graphs for the 3rd to 11th, 13th to 21st, or 

23rd to 31st harmonics, respectively. For example, to display the 13th to 21st 
harmonics screen, press 13-21.

THD

HC

H1

-------- 100



=

thd

HC

H1





2

HC





2

+

----------------------------------------- 100



=

TDD

HCIA





2

HCIB





2

HCIC





2

+

+



 ILoad







100



=

V L-L

U

Line-to-line voltage harmonics data

V L-N

V

Line-to-neutral voltage harmonics data

Amps

I

Current harmonics data

TDD

TDD

Total demand distortion