Petrol/Diesel generator waveforms

[.RC.]

I was interested in looking at the waveforms my generators make compared to mains so I bought one of those cheaper DSO oscilloscopes.  Yes I know they are not amazing wonderful machines, but even the more basic ones are better then none.

Generator is a US made 60Hz welder/generator unit from the Miller brand.  Dates back a dozen years or so.  Capacitor regulated.

Have attached an image of the waveform under no load. This cheap scope does not show the bottom waveform correctly.

I have also attached an image of the waveform when a cheap inverter welder is connected and working.

[.RC.]

I decided to compare waveforms between two different plasma cutters.

First image is a cheap Cut40 machine.  Similar result to the cheap inverter welder

Second image is a UniMig Razorcut45 plasme cutter which the brochure says has power factor correction.

Third image is the same generator running a 2200W kettle

Forgot to mention the generator has a 6kVa at 1 power factor.

[.RC.]

Another test with a much larger (11kVa) AVR generator.

First photo shows the cheap cut40 plasma cutter.  Still have a similar style of waveform.  Does anyone know if this means it is a switching power supply with very poor power factor.  The current is only being drawn at specific times in the cycle leading to the levelling off of the wave form peaks?

Second photo shows a Razorcut 45 plasma. 

Third photo is a transformer type 250 amp MIG welder at full power.