Wiring of Inverter/Home UPS

Discussion in 'General Electronics Chat' started by mmodi, Dec 8, 2008.

  1. mmodi

    mmodi Thread Starter New Member

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    Hi,

    I am using a 800VA (12V) Home UPS System as Inverter/UPS for PC. I need some technical assistance regarding wiring.

    Please let me know:

    - What is the difference between the attched wiring diagrams?

    As I requested to my electrician for wiring as per the diagram “a” for whole house, but he says that it is impractical for the inverter wiring (however, he can do the same for my PC only, and for other appliances like light & fans he adopted “b” method).

    Kindly suggest.

    Thanks with regards,

    M Modi

    Attached Files:

  2. SgtWookie

    SgtWookie Expert

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    Diagram a) is correct.
    Diagram b) is not correct, as there is no return path to the inverter. The inverter should automatically take care of switching between the mains and it's own output.

    If your mains voltage is 120, your inverter will only supply 6.67A output maximum. That is not much power. If it is being run from 12.6v batteries, the drain on them will be about 75 Amperes while the inverter is supplying the 6.67A output. Unless you have a very large bank of batteries, you will have power for only a short period of time.
  3. mmodi

    mmodi Thread Starter New Member

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    Thanks for the reply, I am from India and here the supply Voltage is 220. I know that the Diagram A is ideal, but here mostly Diagram B is in practice (and its working - it may be that inside inverter the mains' neutral is connected to the output neutral of inverter, is it possiable?). This is a Home UPS system with a 135 AH power bank.
  4. SgtWookie

    SgtWookie Expert

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    Since your mains are 220, you'll only get 3.63A from your inverter; your battery draw will still be around 75A. At the very most you will get 1.8 hours of operation at full load, but to maximize your battery life, you should not let it operate for more than about 1/2 hour (full load) on the batteries. Longer than that, and your batteries will become heavily discharged, which is not good for them.
  5. leftyretro

    leftyretro Active Member

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    Here is the USA your circuit example B would not be compliant with electrical safety standards and would be in violation with local and national building codes. The neutral wire in circuit B example would have to carry current back to the panel for both loads.

    It is most likely the same wire size as the single line terminal wire and therefore is in danger of being undersized for the current draw of both loads even if both line wires are protected with a properly sized circuit breaker for the line wire size.

    I would assume that you must use single wire runs in your typical home to even be able to consider wire circuits as shown in your example B. Here we always use 3 conductor cable (line, neutral, ground) and daisy chain to loads and each cable run would typically wire to a 20 or 30 amp circuit beaker. There may be a 6 to 12 such runs in a typical home here.

    Lefty
  6. AnandMisal

    AnandMisal New Member

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    Hi
    I am from India and planning to use UPS / Inverter System at my home.
    What will happen if I connect ( Diag 2 ) HOME UPS Neutral (N) to LOAD ON UPS Neutral and Mains Neutral BOTH. Will that solve my problem of return path OR is it going to create any major issues?

    Regards
    Anand
  7. b.shahvir

    b.shahvir Active Member

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    But wat's the logic behind sharing a common neutral as depicted in fig. (b) ? External neutral means you are atttempting to by-pass the inherent safety equipment of the UPS. This can result in safety issues!
  8. KASIM999

    KASIM999 New Member

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    Iwant to get wiring digrams fof MAXIMA inverter if possible
  9. agnii

    agnii New Member

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    Were you able to follow digram a), if yes what wiring changes it involved.
  10. rajudp

    rajudp New Member

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    i think both a and b are correct. In offline ups the neutral is common for both mains and ups out. But for online primary neutral is isolated with ups out neutral
  11. rogerthatpsr

    rogerthatpsr Member

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    i have one more problem with ups.... i have a 800vA inverter... but i think there's some problem with wiring... IF there's a short somewhere due to failure of any equipment the main line power supply is turned off automatically by dip switch but when this happens the inverter turns ON n starts supplying power to the short making it more complex...the thing will b on fire n smoke until u turn off ups manually or it automatically turns of itself after crossing overload level..... i guess the placement of dip switch is wrong... can any body suggest a proper diagram..?
  12. Good

    Good New Member

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    Looking at the Diagram B what will happen both neutral and live wire of inverter input disconnected(due to any reason)? Will the inverer output will complete the circuit or not .
  13. sudipto_15

    sudipto_15 New Member

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    dear
    what your technician told you that fig 1 is preferred only for computer and fig 2 is prefers for home wiring

    if you have a close look at fig 2
    it reduces your wire cabling and also allow you to run heavy gadgets ..like heating rod ...
    if the technician do the same wireing as fig 1 for whole home .... if overload occurs ... inverter gets damaged
  14. sudipto_15

    sudipto_15 New Member

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    hi,
    I have a microtek inverter 800VA and the problem with that is ....
    when inverter sending charge to the battery the output trips .... but when I remove the charging cable from transformer to the PCB ...there will be no problem

    I remove the charging mosfet and 4N35 IC too ...but result is same...

    can you suggest ...
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