# Interest group forums > Energy and Resource Conservation Forum > [Opinion] Genset vs true sine wave ups

## Alfred M

Graphs of genset loaded to 850w compared to true sine wave ups loaded to 850w. Left scope image ups and right scope image genset.Harmonics clearly visible from genset. I have all my sensitive electronics running through ups for load shedding and genset running.

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## Justloadit

You did not specify what type of genset you tested.

Is the genset a variable speed with a built in pure sine wave inverter?
The saw tooth in the genset wave shape, seems that the filtering is not good, and is usually when the output inductor value is insufficient inductance or being over driven and so looses its inductance. This usually occurs due to the load exceeding the genset capacity.

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## Alfred M

Genset is a v-0-v 5.5kva and the ups is a PSS 1500va

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## Alfred M

Make Macafric

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## Justloadit

Seems they have an electronic AVR and hence the saw tooth you are seeing.
Try loading the genny with resistive load, such as a heater and check the wave form again, then connect the UPS again and check again.
Let us know the results.

using the UPS is best for any sensitive electronic equipment.

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## AndyD

That instability in the sine wave of the second scope trace (generator) isn't showing harmonics nor is it harmonic related. The traces are confusing me a bit, were they measure simultaneously using the 2 channels on the same scope? What scope were you using? Why different coupling and invert settings? Why is the first trace showing 10.5 volts? Why is the inverter and the generator 60Hz waveforms? I've never seen either a 60Hz genny or a 60Hz domestic inverter available in SA and even if they were it would be unauthadox to connect them and they could well cause your home to self combust.  

Apologies for the barrage of questions but honestly I think there's something fundamently hinky with your test measurements ie inconsistant scope setup or with the equipment on test.

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raamonkhan (17-Oct-22)

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