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Recent content by pie314

  1. pie314

    Transformer Inrush - Limited by short circuit availability?

    I of course meant the AIR CORE impedance of the primary winding.
  2. pie314

    Transformer Inrush - Limited by short circuit availability?

    Vanda106 The short circuit impedance has a definite affect on the peak inrush current. High inrush currents occur when the core saturates during the energization. Once the core saturates the current is the voltage divided by the impedance ohms of the transformer.The point at which the core...
  3. pie314

    Reactor Capability

    You CANNOT use the 64 amp rating when the wire is used in an Air Core reactor. Air core reactors can have high eddy currents. Also the wires are blanketed with insulation. Usually the current density in air core reactors is 2000 amps per square inch or less. 64 amps looks very high to me
  4. pie314

    SHUNT REACTOr

    a shunt reactor nameplate has a rating of OA-MT. The OA is oil self cooled, but what does the MT mean? Thanks for any help
  5. pie314

    shunt reactors,series reactors and capacitor banks

    A shunt reactor is a reactor connected line to ground. A series reactor is connected in series. and a capacitor bank is a number of capacitors in a series parallel arrangement usually connected line to ground.
  6. pie314

    Reactor Rating

    The Z= 6% Simply means the maximum short circuit current is 100/6 = 16.67 times normal = 300*16.67 = 5000 amps Also it means the reactor is rated .48 ohms 2400 volts/.48 = 5000 amps
  7. pie314

    Pole-mounted transformers

    IEEE C57.12.30-2010
  8. pie314

    Single phase short circuit current calculation

    Also if the 1.7% is mostly reactance and the short circuit occurs at a voltage zero, the the peak asymetrical current could be 18.4 X 2 X 1.41 = 51.9KA
  9. pie314

    Substation Reactors Standards

    IEEE 32 covers "NEUTRAL GROUNDING REACTORS".AND IEEE 57.16 covers "DRY TYPE AIR CORE AND SERIES CONNECTED REACTORS".
  10. pie314

    Function/usefullness of transfomer interleaving shield?

    Precipitation transformers are typically less than 100 KVA and are Rectifier transformers used to remove smoke particles. Transformers used to test other transformers sometimes require a shield also.
  11. pie314

    Function/usefullness of transfomer interleaving shield?

    Ahandle -- This is sometimes called an "Electrostatic shield". and is usually required when the secondary winding is subjected to arcing. For instance most precipitation transformers require this shield. It is usually a 10 mill copper sheet placed over the secondary winding and then grounded. (...
  12. pie314

    7.2 kV Distribution Shunt Reactors

    I disagree with Magoo2. Air core reactors are more prone to vibration problems than Iron core. As the reactor traverses from zero to its peak current the reactor forces are trying to expand the diameter and shrink the height. Since a shunt reactor sees only rated current these forces are not...
  13. pie314

    7.2 kV Distribution Shunt Reactors

    KMH1 What are the dimensions of the reactor? You mentioned a single phase reactor, but I see (3) reactors in the picture. It looks like a (2) layer design reactor. I assume the the layers are in parallel not series. It could be that the volts per turn are too high. Also shunt reactors are...
  14. pie314

    Inrush Current in HV winding ? Input 380V at 11kV/380V Tx HV side

    I agree with rcwilson except his multiplier of "10 - 12 times". This amount of inrush only occurs if the core saturates. Since the applied voltage is well below rated, the core will not saturate. If the transformer is energized @ a voltage zero, then the multiplier will be a factor of 2 not "10...
  15. pie314

    What is the difference between Damping reactor & harmoincs reactor

    Filter reactors are basically shunt reactors. They are connected in series with a capacitor to create a low impedance path to ground for certain frequencies. A current limiting reactor is connected in series and therefore cannot shunt any harmonics.

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