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Thread: Three phase to single phase

  1. #1
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    Three phase to single phase

    Hi Good Day I have a customer who wants to put a single phase solar inverter system 8000W on a three phase supply, as backup. Can anyone flag up the pitfalls and regs. I suspect he wants push me on loading. I have concerns!😉 Many thanks for all the help I've had previously. Keep safe. Derm

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    Hello

    Only thing reg side i can think of now is that you cannot backfeed, well not more than 4.6kw. Not sure the process to even try get that done anyway.

    As for the single phase into a 3 phase. I am not sure if the output could be split into each phase so to be 2.6kw per phase and then basically create 3 x single phases. This would however need to be done as a backup and not an inline inveter as the loads would not be able to be pulled through the inverter. It would need change over switching sort of deal.

    I must say I am no expert and just my thoughts as it is an intresting topic and keen to find out more from hopefully smarter chaps than myself haha

    Sent from my SM-N960F using Tapatalk

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    1. Yip - Limited to 4.6kw per phase on a shared feeder - stupid regulation but does have merit (and its law)
    2. Convert 3-phase to single phase maybe? unless using all phases for three-phase equipment / loads too high
    3. You need to check if you are allowed unbalanced phases. I have seen in many residential applications that the phases are so unbalanced that adding a single phase inverter to one phase only will go totally "unnoticed"
    4. In a commercial metering environment you will be "punished" (financially) for not balancing your loads across all phases.
    5. Does the client have a dedicated feeder? (see item 4 above)

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    Ok, I have your answer
    According to the AMEU-SALGA standard document for SSEG which is RECCOMMENDED to be applied by municipalities the following under chapter 5 and specifically 5.2:

    "If SSEG generation capacity is 4.6 kVA or less, a single-phase inverter can be installed even if the customer has a three-phase connection. Systems above 4.6 kVA are required to be balanced across the phases."

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    Dave A (17-Jul-21)

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    Quote Originally Posted by lyndsay View Post
    Ok, I have your answer
    According to the AMEU-SALGA standard document for SSEG which is RECCOMMENDED to be applied by municipalities the following under chapter 5 and specifically 5.2:

    "If SSEG generation capacity is 4.6 kVA or less, a single-phase inverter can be installed even if the customer has a three-phase connection. Systems above 4.6 kVA are required to be balanced across the phases."
    Brilliant thank you !

    Sent from my SM-N960F using Tapatalk

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    If you are having shared feeding 25%
    if you are having dedicated feeding 75%
    NRS also states about how much VA you are allow to push in on single to 3 phase system,and what also plays a huge role is your Rated Circuit breaker supplied by council.
    What about having 3 inverters on all 3 phases?
    I have not seen any system or 1 inverter being splits onto a 3 phase system,you can do it but you will have to only supply 1 of the phases.
    If he is having a 3 phase system it will be expensive but more profitable in the long run because he will produce much more yield.
    No expert

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