Do Street Transformers Work Together or Are There Disconnections between Each Transformer When Powering Houses?

stealthmatt on 03/04/2018 - 09:26
Last edited 03/04/2018 - 10:01 by 1 other user

Hi all,

My street has high voltage issue and our grid provider is coming out to tweak the transformer.

However, around my street there are 3 pole transformers and when I follow the power lines they all seem to connect to each other. i.e there is no disconnection everything is connected.

Note: I am talking about the house voltage wires 240 volts (not the high voltage lines)

Do multiple transformers work on the same street wires? or is there a disconnection of the wire I am not seeing and 1 transformer powers 1 street.

If multiple transformers work together, how do they stop from killing each other and fighting each other for voltage etc.

Thanks in advance

• 

  MathNerd on 03/04/2018 - 09:48

  Here's your answer.

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  retiredfeline on 03/04/2018 - 09:53

  If multiple transformers work together, how do they stop from killing each other and fighting each other for voltage etc.

  Each house has only one feed.

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  uzz30 on 03/04/2018 - 10:01

  +2

  I relayed your question to a power network engineer at a major electricity distribution company, he's been kind enough to provide an answer on very good authority.

  Note : LV = Low Voltage (230 Volts - Your home supply voltage)

  "LV (230V) network is built so that it can be supplied from different transformers so that network can be reconfigured to keep supply on if a transformer fails (it can take a while to replace a transformer). In general the LV is only supplied from one transformer.
  There are definitely disconnections. Typically called LV links."

  "There is a system to track this emergency configuration so that when the transformer is fixed the LV network is not paralleled (ie supplied by 2 transformers). This is mainly a safety issue for the field guys as something might be live when they expect it to be dead."

  • 

    stealthmatt on 03/04/2018 - 10:09

    +1

    Thank you

    • 

      BensonP on 03/04/2018 - 10:48

      Oops see below. I replied to the wrong guy haha

  • 

    BensonP on 03/04/2018 - 10:47

    +2

    I also work in power distribution and transmission :)

    The same principle is used from pole top transformers (such as OP is asking about), all the way up to 500,000 volt transformers.
    And even in regards to transmission, generally two sources (bus, plural busses), will supply lines and transformers, through two seperate circuit breakers.
    In the event one supply bus fails, or circuit breaker fails, one circuit breaker can trip/open, and the line can stay energised by the other bus.

    Hope this clarifies

• 

  c64 on 03/04/2018 - 10:31

  i cycled past transformers that are continually buzzing all day long. i feel sorry for people living near them.

  • 

    inherentchoice on 03/04/2018 - 10:47

    +2

    Transformers are fictional, so they can't be buzzing all day. In any case the Decepticons don't work together with the Emoticons.

    • 

      retiredfeline on 03/04/2018 - 10:50

      +1

      Friend of mine used to say those (battery operated) toys transformed 1.5V to 0V (well some terminal cell voltage anyway).

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  idontalwaysnotlie on 03/04/2018 - 10:48

  +2

  I work in this area so can help explain some things a bit.
  Most low voltage networks work in a radial design with a single transformer supplying a street or two.
  They are usually interconnected so we can switch the load around faults or for maintenance.
  A few years back we moved to the international standard of 230v but the actual voltage can vary greatly.
  The usual range is 216V-253V with 207-262 allowed for maintenance or unusual conditions.

  The voltage drops along the line with each house connected so right near the transformer it might be 250V but down the end of a line it will drop to 220v.
  High volts is a growing issue usually resulting from solar feed in as the network was designed to go in one direction.
  Having power sources mid line pushes up the voltage during the day but then drops the volts at night which makes it tricky to plan for.

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  bdl on 03/04/2018 - 16:16

  This is the only time I have seen Transformers work together: https://www.youtube.com/watch?v=BYOWdUiflTg

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  TheBilly on 03/04/2018 - 17:48

  Think of Electrical Circuitry like train lines. They all work together, but there is only one going to the fat controllers end of day repair depot.

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  stealthmatt on 05/04/2018 - 09:09

  I had someone reply in another forum:

  Street transformers (or more technically, distribution transformers) do not work together (or in parallel). Their supplies are disconnected from each other.

  There is no need to run distribution transformers in parallel. A reason to run power transformers in parallel is to achieve maximum efficiency because power transformers have maximum efficiency at full load. Since distribution transformers are designed so that their efficiency is at low load, and efficiency decrease with load increase, there is no need for parallel operation.

  If reliability is what you're after, then this system allows you to manually shift load from one transformer to the other provided the other transformer can carry the extra load.

  Thirdly, transformer synchronization has its own conditions which are very difficult to achieve and maintain for a distribution transformer.

  Here are the conditions for parallel operation of transformer:

  • Same voltage Ratio & Turns Ratio (both primary and secondary Voltage Rating is same).
  • Same Percentage Impedance and X/R ratio.
  • Identical Position of Tap changer.
  • Same KVA ratings.
  • Same Phase angle shift (vector group are same).
  • Same Frequency rating.
  • Same Polarity.
  • Same Phase sequence.

  Most of these conditions are very difficult to achieve with distribution transformers because of the variable nature of the load. A load on a distribution transformer swings widely and they are designed to work satisfactorily for a wide range of loads. Thus, it is for these reasons that a distribution transformer is used in isolation.