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Voltage source connected with parallel.

  1. Aug 3, 2010 #1
    Hi, if i add to different voltage source in parallel what will happen. I know that KVL forbid that and in pspice it shows simulation error. But i want to know what will really happen in practice.
    Similarly to different current source in series?
  2. jcsd
  3. Aug 3, 2010 #2
    You have to take the real circuit resistances and voltage source resistances into account.

    Then you can use Spice or Kirchoff.
  4. Aug 3, 2010 #3
    for parallel connection of voltage source, following are important points to come to conclusions:
    *whether blocking diodes are used for avoiding reverse current flow?
    *difference of both sources no load voltage?
    *difference internal impedance of both sources?
    *whether any load connected to this parallel combination?
  5. Aug 4, 2010 #4
    OK.......no diodes are added, and a resistance is added parallel to that combination.
    What will happen?
  6. Aug 5, 2010 #5
    If no diodes are added and if the internal impedance of the sources are not equal then there will be circulating currents between the sources, even if their voltages are same,which is highly undesirable. That's why we should add blocking diodes.
  7. Aug 5, 2010 #6
    So post your circuit and your analysis attempt so that we can discuss it.
  8. Aug 5, 2010 #7


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    This thread is a good example in which using a simulator alone can lose the essence of basic Science.
    A voltage source has zero internal resistance so a computer simulation has to decide what do do when about a nonsense answer would result from some 'impossible' input values. It can either say "Sorry, can't do it guv' " or assume that its voltage source has a finite resistance. People don't like the "can't do it" response and are often prepared to accept a more 'friendly' answer. But you must beware.

    I think it is necessary to go back to the original circuit and decide what, exactly, the parameters of the 'voltage source', which, being a theoretical concept, can source or sink as much current as necessary to produce its voltage. This is, potentially, a smoke making machine! It's another GIGO moment.
  9. Feb 10, 2011 #8
    well its a long confusion of mine. However i have got one answers that if two different voltage source are connected in parallel then the output will be the highest voltage value. Because the higher value will suppress the lower voltage which is connected in parallel. And if two different current sources are connected in series then the amount of current flowing is the lower current source. Coz higher current can't pass through the lower current source.
  10. Feb 10, 2011 #9


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    An 'ideal' voltage source maintains its voltage whatever you do to it. Hence, the thought experiment is actually meaningless because it would involve infinite current flowing from the higher voltage source to the lower one.

    In practical terms, if you connect two hefty batteries then everything will get hot until one has gone flat or the other has boiled dry.

    Simulators are very much GIGO devices. Beware of any conclusions you draw from them when inputting unrealistic values. They are a bit like a lot of other software that can 'do your thinking for you' and, rather than throw up an error, they will substitute values which avoid inconvenient results.

    Keep you feet on reality; fit simulated fuses and read the actual characteristics of all simulated components.
  11. Sep 16, 2011 #10
    different value ideal voltage source in parallel is not defined. Only same value ideal voltage source can be connected in parallel.
    for the non-ideal case, theorems are available.

    I hope this answer the question.
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