Current through a 220V line

Discussion in 'General Electronics Chat' started by kahafeez, Jul 3, 2009.

  1. kahafeez

    Thread Starter Active Member

    Dec 2, 2008
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    Hello, i live in Asia and here the AC voltage is 220V... can anyone please tell what is the value of current ??? according to my understanding its 10Amperes. but i am not sure.... plz help...
     
  2. alim

    Senior Member

    Dec 27, 2005
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    Your question is vague. Wht current are you asking about, is it from the power supplier, or is it your inlet demand that you require. For the first see the power company , for the second your installation tech would tell you.
     
  3. studiot

    AAC Fanatic!

    Nov 9, 2007
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    The current drawn depends upon the power rating of device you connect to the supply.

    The voltage is always fixed at 220V.

    You cannot specify both current and voltage at the same time.

    The current is mostly the power divided by the voltage = P/220 in amps.

    So 10 amps corresponds to a 2200 watt (2.2 KW) device.
     
  4. alphacat

    Active Member

    Jun 6, 2009
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    To be more correct, the current drawn from the power plant is S / V.
     
  5. kahafeez

    Thread Starter Active Member

    Dec 2, 2008
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    thanks everyone.... i wanted to ask about the current supplied from the power company.... and i've come to a conclusion that the current's amount is not fixed... it depends upon the appliance.... righto ???
     
  6. loosewire

    AAC Fanatic!

    Apr 25, 2008
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    Kahafeez, Do you have curcuit breakers or fuses in your panel,maybe I can help.
    Do you have a.c.(air condition) in your house. It will help you understand more
    If you answer.
     
    Last edited: Jul 3, 2009
  7. studiot

    AAC Fanatic!

    Nov 9, 2007
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    You're getting there.

    If you have more than one appliance, the voltage stays the same (220). You add the together the currents for each appliance to get the total current.

    So 20 x 1/2 amp light bulbs make 10 amps.
    2 x 5 amp electric fire bars makes 10 amps
    1 elctric fire bar plus 2 light bulbs makes 6 amps.

    and so on
     
  8. studiot

    AAC Fanatic!

    Nov 9, 2007
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    That's an interesting concept, where in the world does this apply Alberto?

    Breakers in the UK are only there for safety purposes, there is not such contract limit. If I draw more I pay more.
     
  9. b.shahvir

    Active Member

    Jan 6, 2009
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    I also do agree with Alberto. Although I'm not aware of any contract demand, in my case I would have to intimate the electric company before hand if I need to increase my connected load! This also applies to change in type of supply system availed for, single phase or three phase.
     
  10. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Under the Electricity Acts, you have to state the expected maximum demand. The supply company then has an obligation to supply this.

    Of course they can charge extra for huge MD, although they often offer discounts for lowering your MD or timing it out of peak hours.
    If it was ridiculously high you might also end up paying for extra cabling in the street - not a cheap prospect.

    If you keep within accepted norms a domestic supply will be protected by a 100amp fuse, whatever size of supply you anticipate. At Uk voltages this = 24KVA.
     
  11. alim

    Senior Member

    Dec 27, 2005
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    Where I am we pay what is called 'installed capacity' , i.e. your main switch capacity times the supply voltage, which amounts to what Alberto has said.
     
  12. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Maldives !!! DUH!! :eek:
    We have like 32A max for a single phase

    Rifaa
     
  13. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Some instantaneous water heaters (for showers) are 8KW by themselves.

    You still have to apply what our regs call 'diversity' to keep under 24KVA.

    That is you won't have the shower, electric cooker, all the lights, heating, all going at once. If you do all that it can be very easy to clock up the 24KVA.
     
  14. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Yes I think some showers produce a lot of steam, however these are the values on the rating plates.

    The Germans use the between phase (415) voltage for this to reduce the current draw.

    They require special wiring and cannot be plugged into an ordinary 3KW socket. Similarly cookers, hobs etc have too high a rating for ordinary sockets. We do no have many air conditioners in the UK but these could also need this type of supply.
     
  15. Wendy

    Moderator

    Mar 24, 2008
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    Wish I could say that about Dallas. We peaked at 103°F (39°C) yesterday, and have had about a month of this weather with some minor breaks. Here 2 phase 220VAC is the norm, with each phase providing several 120VAC wall outlet legs. The 220AC is saved for the heavy appliances, such as the stoves, laundry dryers, and AC. Won't swear to it, but I think we have a 100A breaker in the box, mostly for total house disconnect. Each leg has smaller breakers, 15A 120VAC being the usual, and at 15A most of these breakers actually trip early, say 12A or so.
     
  16. b.shahvir

    Active Member

    Jan 6, 2009
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    I think it must be single phase 3-wire system (2 hot legs & 1 neutral). This might be derived from the three phase distribution systems which is then segregated by pole-mounted drum type single phase transformers, the secondary of which is single phase 3-wire type.

    220VAC is available between the outer 2 hot legs (for heavy loads) and 120VAC is available between either hot leg and the centre neutral wire. When one says 2-phase system then it would mean the 2 phases are 90 elec. deg. out of phase w.r.t. each other. Also, the neutral wire would carry a continuous out of balance current of √2 times the current in either of the outer hot legs...and as such this might not occur in the case you mentioned above! A single phase 3-wire system neutral carries current only when the loads between outer hot legs and neutral wire are un-balanced and not continuously as is the case in a 2 phase 3-wire system.

    Regards,
    Shahvir
     
  17. Wendy

    Moderator

    Mar 24, 2008
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    You're right, it was a brain fart on my part. The term used is split phase electric power. You have to love Wikipedia.
     
  18. b.shahvir

    Active Member

    Jan 6, 2009
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    Brain -farting is a modern day disease :D. Thanx for the link anyways.

    Regards,
    Shahvir
     
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