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Author Topic: Generator power - Why square waves are bad, and other things to look out for.  (Read 18441 times)

Mac Kerr

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OK.  Just for s***s and giggles, here's a shot of the trace of an APC UPS, $165 from Office Max.  Two different resolutions...

Now the question is, does that matter any more than the stepping of a digitally sampled audio signal that is being converted to analog?

Mac
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g'bye, Dick Rees

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Now the question is, does that matter any more than the stepping of a digitally sampled audio signal that is being converted to analog?

Mac

I was told not.  But as I said, it was posted for giggles.
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Tim McCulloch

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I was told not.  But as I said, it was posted for giggles.

I worked with Giggles.  She was in the lighting dept at Baltimore Fishmarket (drinking in Disneyland) before it went under.
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John Roberts {JR}

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OK.  Just for s***s and giggles, here's a shot of the trace of an APC UPS, $165 from Office Max.  Two different resolutions...

And what in the world does this have to do with generators?

JR
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Mike Sokol

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Now the question is, does that matter any more than the stepping of a digitally sampled audio signal that is being converted to analog?

Mac

From the times I've been forced to run sound gear from a modified sine wave inverter (a parade float running from a cheap inverter in a pickup truck), I've noted there's a lot of extra buzzing going on just from all those harmonics in the waveform. In a D/A converter there's going to be some sort of low-pass filter to get rid of the ultrasonic frequencies (at least there should be). And most of the high frequency harmonics of the stepped sine output would be absorbed by the gear's power transformer. But those harmonics are like really bad triac lighting dimmers, and get into every guitar and high-impedance audio input.

I would agree that the Inverter generators from Honda are simply amazing with their clean AC output, and it's that same inverter function that allows them to run in eco-mode which throttles back the engine RPM to converse fuel when the electrical load is low. As noted earlier in this thread, a standard generator has to run at a constant RPM (1800 or 3600) to keep the frequency at 60 Hz. But the Honda's are smart enough that you can parallel two of them together and their outputs will phase-lock to each other at 60 Hz. Talk about cool stuff...

g'bye, Dick Rees

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And what in the world does this have to do with generators?

JR

Nothing.  It has everything to do with the interest in the "purity" of the wave forms.  I presented the pic simply as a visual representation of what some inverters do.

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John Roberts {JR}

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Nothing.  It has everything to do with the interest in the "purity" of the wave forms.  I presented the pic simply as a visual representation of what some inverters do.
The natural output of a motor/generator is sinusoidal. Any distortion or reduced purity is likely related to load and source impedance, typically resulting in flattened waveform top/bottoms.

Inverters are a completely different technology converting DC to AC often with step wise waveform approximations. This extraneous information is IMO not germane to using a generator.

I will repeat my original advice that a distorted (I.E. flat topped) generator voltage waveform may not measure similarly to a clean sine wave. Care should be taken regarding measurements especially if used to make voltage adjustments. 

JR
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