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I recently learnt about the synchronisation of alternators using Two bright and one dark lamp method. In this arrangement, lamps are connected between two sources. We done the practical using an alternator synchronising with the mains voltage 230v. Alternator was connected in star connection, well it was driven by a dc motor.

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As I understand current flows back to the source, but in the real world because of the parasitic capacitance that will seems like a lie. But in the synchronisation, how does the lamps glow? how does the current flow between those two sources? The neutral point of the alternator wasn't connected to anywhere either.

I asked this Question before. Static-charges can flow to another but not in current electricity as I understand. We can't use two independent sources without having a common point there, so we always connect ground or negative in DC systems. How does this happen then?Is there something I missed?

I'm an electrical engineering student and I hope someone can provide me a good answer.

Thanks

Aimkiller
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  • Because a voltage difference is applied over said lamp. – winny Mar 10 '20 at 07:48
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    There is no ground in this circuit, and no neutral either. Just three phases. The three phases are always 120 degrees out of phase with each other, so will always be at different voltages. The lamps are measuring the voltage difference between phases. – Simon B Mar 10 '20 at 08:37
  • @winny well if there is not parasitic capacitance there would be no current flows to the ground if an earth fault happens in a ungrounded delta system. If we consider earth is zero-potential there would be huge amount of current. But without earthing transformers there is only a little of current due to parasitic capacitance. I asked the question based on this and current flows back to the source – Aimkiller Mar 10 '20 at 08:56
  • @SimonB please see the above comment – Aimkiller Mar 10 '20 at 08:57
  • No need for any parasitic capacitance anywhere to make the lamps light up. – winny Mar 10 '20 at 09:17
  • @winny so between to sources current can flow through like this – Aimkiller Mar 10 '20 at 09:33
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    The circuit doesn't assume any ground anywhere. It would work just as well floating in outer space, millions of miles from any planet. – Simon B Mar 10 '20 at 10:34
  • @Aimkiller Why wouldn't it? – winny Mar 10 '20 at 13:54

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