Plug packs
Waveforms
Charger input waveforms, 0.2A/square, screen edges and centre are the input voltage zero crossings
Green wallwart AD5953 ALF, XO1.5 running 93% charge 240V input
as above but run on battery power down to 80% charge then plugged in
Green wallwart Delta ADP17FBA, XO1.5 running 93% charge 240V input
White wallwart Bestek NA0241WAA, XO1.5 running 93% charge 240V input
For comparison a PC power supply. Vertical scale is 0.4A/square, the waveform has a wider pulse and could be expected to be less stressful on generators and transformers but not much better.
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
yielded this result
