grid-tied inverter drop-out

Discussion in 'General Electronics Chat' started by Handymanjack, Jun 20, 2011.

  1. Handymanjack

    Thread Starter New Member

    Jun 20, 2011
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    Why is it necessary for a grid-tied inverter that is supplying power to my home and feeding the grid at the same time, stop functioning if the utility goes down? Could not a current sensing breaker on the utility's input be tripped thus letting the inverter continue to supply my home? regards, Handymanjack
     
  2. debe

    Well-Known Member

    Sep 21, 2010
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    184
    They are designed that way for safety so they dont feed back in to the system as a linesman may bee working on them. Also they need the mains for frequency control.
     
  3. Handymanjack

    Thread Starter New Member

    Jun 20, 2011
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    Thanks for your answer but my second question was: Could not a current sensing breaker on the utility's input be tripped thus letting the inverter continue to supply my home? Also inverters have their own 60Hz frequency control. Handymanjack
     
  4. debe

    Well-Known Member

    Sep 21, 2010
    946
    184
    I was under the impression they didnt have a 60HZ freq generator as they used the mains freq to generate the freq so that is in phase.
     
  5. NLightNMe

    New Member

    Apr 20, 2011
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    A grid-tied inverter would need to match the phase on the 50/60 Hz on the mains. Most inverters generate their switching frequency from the signal on the mains, but there isn't any reason that they couldn't have an independent generator for the 60 Hz. The problem is that when the grid was off and your system was running completely independently, the 60 Hz reference would continue to clock your system. When the grid came back up, the phase of the mains signal would be off from your inverter reference. The inverter would need to gently manipulate the energy to match before it could go back to being 'grid-tied'. This can, of course, be done. It is simply not economical to do so with most inverters.

    Look at more complex systems with battery back-up - a grid-tied, battery back-up PV installation. They should have an additional box that handles the power matching (phase, frequency, level) between the grid, the inverter, and the battery system.
     
  6. Handymanjack

    Thread Starter New Member

    Jun 20, 2011
    3
    0
    This fact I did not know and it would answer my question - I would gladly pay the extra cost for the 60Hz oscillator - I'll check this out, HandymanJack - Thank U both for replying!
     
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