How a phone center office still generate power to rj-11 port when breakdown?

Discussion in 'Electrical Forum discussion & Blog' started by jonathan, Dec 3, 2009.

  1. jonathan

    jonathan New Member

    Messages:
    3
    Location:
    malaysia
    hi all,

    as we know the rj-11 which generate 48DV voltage from the center office.
    even when our house electricity break down we still can make call.
    if the center office also break down ? does the rj-11 still supply power to our phone? how does it work ? my lecturer say it still can make call! but where does the energy came from ? does the rj-11 can store enegy for a long duration? or the center office have a very large power generator ? if got a generator it support to MIllion of people at once ? i think that is impossible. OR maybe center office there got many capacitor attach to the rj-11 port circuit....

    i'm really confuse at it ... can someone give me a guidance ?
    Last edited: Dec 3, 2009
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    BATTERIES. Phones systems have always operated on batteries!
  3. jonathan

    jonathan New Member

    Messages:
    3
    Location:
    malaysia
    emmm ...jimbo .... u mean the batteries is in the phone or the rj-11 port got battery inside ? if u mean the batteries for the phone, then is not i wanted. because i mean the old fashion phone without display or any other function. just for normal call only.

    if u mean the battery is inside the rj-11 port.... mean got battery inside work like capasitor ? / or maybe the battery is at the center office side.
  4. ecofarmer

    ecofarmer New Member

    Messages:
    10
    The phone system runs off a battery system. The batteries are at offices thorough the country and have back up AC or DC generators depending on the office setup.
  5. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    The power is in the central office. The 48 volts DC, or 32 volts DC in centrex systems, comes through the wires to your house, where it powers the electronic circuits in your phone. Of course, any kind of phone which requires plugged in to AC power at your house to run its electronic feature circuits, such as cordless phone, answer machine, etc.....THESE will not work without the AC line power in your house.

    That is why it is good to keep one regular plain old phone in the house, so when the cordless won't work, and the cell phones won't work, there is a good chance your plain old phone will work.
  6. Redwood

    Redwood Master Plumber

    Messages:
    7,452
    Location:
    Connecticut
    Here's some batteries at the phone company...

    [​IMG]
  7. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    Can you imagine shorting this array? It would probably melt a crowbar. Violently.
  8. jar546

    jar546 In the Trades

    Messages:
    432
    Location:
    USA
    Great photo. I used to do all of the power cut ins for these battery banks in phone company co's. They only allow cut ins between 12a-6a to minimize the risk of losing phone service. There are backups of backups of backups inside most phone company co's. Many large city buildings have no windows for security purposes.
  9. jonathan

    jonathan New Member

    Messages:
    3
    Location:
    malaysia
    thx jimbo and reawood.... never thought have those battery bank at all =D
  10. thassler

    thassler New Member

    Messages:
    106
    Location:
    Tennessee
    I witnessed a dropped crescent wrench at one of these at a telco. It landed across 2 copper bus bars completing the circuit. It turned a spectacular color of white before melting.
  11. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I am a little surprised at the photo, unless I can't see well. Are all those racks just bare steel? Light fixtures open to atmosphere??

    On submarines, we have a bank of 125 batteries. Each cell is about the size of 8 of those in the picture. The entire battery compartment is specially treated oak battens, and everything metal is coated with a heavy coating of plastisol. No metal goes into the compartment. You leave your watch, belt buckle, etc at the entrance hatch. All tools needed are specially coated and kept in the compartment. Light fixtures are of the explosion proof rated type. Hydrogen is nasty!
  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,924
    Location:
    New England
    Hydrogen in a sealed up submarine verses a building where you could vent to the outside are two different animals. Big problems if the ventilation fails, though, in either case.
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