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UPS that accepts multiple power sources

  1. Apr 22, 2017 #1
    Hi,

    I'm looking for a device that is able to provide stable power and alternate between power sources. UPS, no matter how good they are, they usually still have several millisecond downtime during outage, switching from power grid to backup battery. I want a device that can accept power from multiple sources, both AC and DC, store to some powerbank first (plugable modular powerbank would be nice) before distributing to house appliances.
    The tool may look like this
    tool_zpsjjdmoowe.png

    This way, it can reliably provide electricity with stable voltage with no down time at all.

    Thanks
     
  2. jcsd
  3. Apr 23, 2017 #2

    Tom.G

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    Larger Uninterruptible Power Supplies (>1KVA) are often designed so that the Inverter always supplies your load, and the incoming power both charges the batteries and powers the Inverter. When the incoming power fails there is no switching delay because the Inverter is already operating.

    Incoming Power --> Battery --> Inverter --> Load

    For a decent overview see: https://en.wikipedia.org/wiki/Uninterruptible_power_supply
     
  4. Apr 23, 2017 #3
    I see. just to make sure, on that wikipedia article, what I'm looking for is the Online / Double Conversion UPS? and they can handle multiple power sources? so, I'll have an array of battery of 200 kWH for spare in case of outage.
    thanks
     
  5. Apr 23, 2017 #4

    Tom.G

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    Yes.
    It's not that they handle multiple power sources. They are always supplying your load from the Inverter, which is supplied by the Battery, which is kept charged by the Incoming Power. If you have multiple options of incoming power you could switch the battery charging between them as needed, without interrupting your load.
     
  6. Apr 23, 2017 #5
    so, there's a UPS that can alternate between internal battery and external batteries? because I'm sure the normal batteries inside UPS will only last like 30 mins tops, I have an array of batteries that can last days, so I want to alternate between main power grid and said array of batteries during outage.
    thanks
     
  7. Apr 23, 2017 #6

    Tom.G

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    Not that I'm aware of. Just connect all the batteries together and keep them charged.

    P.S. I don't recall the details, but I've seen external battery packs advertised by at least one of the major UPS suppliers. Very large UPS installations (>10KWH) use only a separate bank, often located in a dedicated room to keep spills and corrosive fumes away from the electronics (and people.) In fact in the USA there are very specific safety requirements for battery bank installations. You must:
    • Contain spills (don't count on concrete floors to contain Lead-Acid batteries, the acid dissolves concrete, and the reinforcing steel bars in the concrete)
    • Supply adequate ventilation (Lead-Acid batteries emit explosive Hydrogen gas, especially during charging)
    • Meet Electrrical codes for Disconnect Switch, current limiting, etc. (A large battery bank easily supplies several thousand Amps into a short circuit)
    Other battery chemistries have their own specific hazards.

    Take care and have fun! Let us know how it all turns out.
     
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