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Onan 5500 Generator


SWharton

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We have pulled the plug and bought a motor home, thank you all for your help.

 

The new motor home comes with an Onan 5500 Gas generator but no where on the Onan site can I determine if it is a pure sine wave generator and our salesman had no idea what we were asking.

 

Does anyone know?

 

Thanks

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All generators are pure sine wave machines.

 

What about the whole line of new portable Inverter generators - i.e. Honda, Yamaha, etc? Pure or modified sine wave?

 

I wonder if Onan, etc will start making a line of Inverter generators for permanent installation in RV's - No need for a constant 3600 rpm during low load use.

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Generators might put out an oscillating wave, but it is not always a pure 60HZ sinewave and can vary under load. Put an oscilloscope on a contractors generator sometime and you will will know it is not a pure 60HZ sinewave. That is why many generators use inverters, to smooth it out to a clean 60HZ pure sinewave.

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duffman, the way I see it, unless Honda, Yamaha, etc. start producing a genny that will fit in most RV compartments made for gennys, that would be a direct replacement for the Onans, I don't see it happening. Believe me, if it were to happen, I'd be one of the first in line to by one and the next move would be to make my Onan a boat anchor!

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I think sine wave generators are relatively new. The sine wave is now needed for all our electronics, prior to the influx of electronics I don't think a sine wave was needed.

 

Nope, the first generators were pure sine wave. Rotating a coil in a magnetic field or rotating a magnet in a coli produces a sine wave.

Although early on there were some generators that output a pulsating dc (they were called dynamos) dc power transmission lost the battle to ac power transmission (Edison versus Tesla) and generators were used thereafter.

 

 

Although we called the dynamos in automobiles generators they were really dynamos and used brushes and coils arranged so that the output was a series of half sine waves which the battery smoothed into a dc voltage with some ripple.

Automotive alternators (which produce a sine wave) came along when solid state diodes got cheap enough to rectify the ac into a series of half sine waves which the battery again smoothed in dc. This meant the brushes did not have to carry the output current since the current could be pulled from the field coils instead of the rotor and two slip rings and brushes carried current into the rotor/coil to produce the magnetic field needed. They were cheaper to make and lasted much longer with less maintenance.

 

Regarding electronics - the incoming sine wave power is rectified into pulsating dc voltage which is smoothed into a very low ripple dc voltage. Switching power supplies operate differently but the end result is the same.

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A non-inverter generator does a pretty good sinewave output at lower loading levels but as you approach the maximum ratings the waveform will start to distort as the peaks sag due to the coils not being able to supply the required current while maintaining the voltage. The peak sag isn't usually a problem aside from microwave and transformer based battery chargers, they still work but the power level drops a good bit.

 

I got these from a friend with a nice scope:

Onan_1_zpsnumy6gil.jpg

Onan_2_zpsxevkq1ff.jpg

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