 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Electronics : Generator conundrum
| Author | Message | ||||
Murphy's friend Guru  Joined: 04/10/2019 Location: AustraliaPosts: 648 |
I have a inverter style 2KW pure sine wave generator, its working well. But it has a feature that has always intrigued me. There is a separate (different style) AC outlet that allows two identical generators to be connected in parallel for double power. To use this feature a special cable is required: https://itechworld.com.au/collections/generator-accessories/products/redback-parallel-cable-for-rb2-generator Its not cheap and I do not have a second generator anyway. But curiosity is nagging me, how does this work? I looked behind the panel of my generator and found the separate AC outlet is wired in parallel with the standard one (2 wires, no earth). The only difference is a tiny switch that turns ON when the parallel cable plug is inserted. The two switch wires go to a potted, sealed electronics assembly that houses all the inverter parts and associated electronics. I have no idea what it switches. Out of curiosity I wired another switch in parallel with the one in the plug so I could observe what inserting that special AC plug does to the output. Well, nothing. The sine wave looks just the same, switch on or off. So I wired my generator in parallel with a small test inverter I have, inserting two neon lights in series in one of the AC wires. Turning both on shows the generator and my small inverter are slowly drifting in and out of sync with the little switch on or off making no difference. So in a real connection there would be a 'bang' event  .What do the knowledgeable forumites think could be inside that box at the hyperlink above? Its a 99 dollar question  . |
||||
Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1024 |
Depends on the brand of generator. Did a Quick search for "Parallel Cable for Generator diagram" https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29344040/print/true.cfm Seems like some of them are a, Do it at your own risk, type of setup. Cheers Aaron Off The Grid |
||||
| noneyabussiness Guru Joined: 31/07/2017 Location: AustraliaPosts: 512 |
maybe it has a sync funtion, as your gen may put out a " clock " superimposed in the sine wave that can be picked up by the 2nd gen to sync to ( sort of how Ethernet over power line works).. bet it would be " proprietary " ... I think it works !! |
||||
| Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 648 |
Thanks for that, I try to see on my CRO if there is something superimposed on the sine wave. Its got to sync somehow, I can't see how the method referred to in Aaron's post would not constantly blow fuses. Its just that I'm curious how its done. |
||||
phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2135 |
"So I wired my generator in parallel with a small test inverter I have, inserting two neon lights in series in one of the AC wires" As an experiment to see if it can auto-synchronize repeat the above, but with heater (say 1000W N direct to N, A to A via the heater) in place of the neon lights. That might allow enough current to get the auto-synchronization to work without allowing enough to do damage if it doesn't sync. |
||||
| analog8484 Senior Member  Joined: 11/11/2021 Location: United StatesPosts: 108 |
No special superimposed signals are used in typical parallel-able inverter generators. Each generator has an output relay and monitors the voltage on the output connector. Whenever the generator starts up (output relay open, no output) it checks for output connector voltage and switches to voltage follower mode if there is a qualified output voltage waveform. In voltage follower mode, the generator will monitor the output connector voltage for some number of cycles to determine key metrics (e.g. peak, frequency, etc.) for its output waveform synchronization and close the output relay then start voltage output at a zero crossing. The voltage output waveform can vary slightly in terms of amplitude and phase cycle by cycle to ensure proper current range. Whenever unsafe condition is detected the generator will open the output relay and shutoff output. |
||||
 Print this page |
