Plug packs

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Waveforms

Charger input waveforms, 0.2A/square, screen edges and centre are the input voltage zero crossings

Chargerwaveform1.jpg

Green wallwart AD5953 ALF, XO1.5 running 93% charge 240V input

Chargerwaveform4.jpg

as above but run on battery power to 80% then plug in

Chargerwaveform2.jpg

Green wallwart Delta ADP17FBA, XO1.5 running 93% charge 240V input

Chargerwaveform3.jpg

White wallwart Bestek NA0241WAA, XO1.5 running 93% charge 240V input

Harmonics

The load is well balanced with respect to leading/lagging power factor, showing only a slight leading or capacitive power factor. The waveform is very rich in harmonics. This could lead to overheating in transformers and generators due to eddy currents.

A harmonic analysis on the following approximation of the waveform

Assumed waveform.jpg

yielded this result

Fourier analysis.jpg

File:Plugpack harmonics.xls

Refs

http://www.idc-online.com/technical_references/pdfs/electrical_engineering/Generators_and_nonlinear_loads.pdf