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Medium Voltage Technical Guide // Basics for MV cubicle design – Schneider Electric
Medium Voltage Technical Guide // Basics for MV cubicle design – Schneider Electric

Prefabricated metal-enclosed switchgear

In order to design a medium-voltage cubicle, you need to know the following basic magnitudes:

  • Voltage
  • Current
  • Frequency
  • Short-circuit power.

The voltage, the rated current and the rated frequency are often known or can easily be defined, but how can we calculate the short-circuit power or current at a given point in an installation? Knowing the short-circuit power of the network allows us to choose the various parts of a switchboard which must withstand significant temperature rises and electrodynamic constraints.

Knowing the voltage (kV) will allow us to define the dielectric withstand of the components (E.g.: circuit breakers, insulators, CT)

Disconnection, control and protection of electrical networks is achieved by using switchgear. Metal enclosed switchgear is sub-divided into three types: metal-clad, compartmented and block.


Short-circuit power

The short-circuit power depends directly on the network configuration and the impedance of its components: lines, cables, transformers, motors… through which the short-circuit current passes. It is the maximum power that the network can provide to an installation during a fault, expressed in MVA or in kA rms for a given operating voltage.

Possible sources of short circuit
Possible sources of short circuit

The customer generally imposes the value of short-circuit power on us because we rarely have the information required to calculate it. Determination of the short-circuit power requires analysis of the power flows feeding the short-circuit in the worst possible case.

Possible sources are:

  1. Network incomer via power transformers.
  2. Generator incomer.
  3. Power feedback due to rotary sets (motors, etc); or via MV/LV transformaters.
Title:Medium Voltage Technical Guide // Basics for MV cubicle design – Schneider Electric
Format:PDF
Size:2.0 MB
Pages:84
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Medium Voltage Technical Guide // Basics for MV cubicle design – Schneider Electric
Medium Voltage Technical Guide // Basics for MV cubicle design – Schneider Electric

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Page edited by E.C. (Google).

9 Comments

  1. lot of thanks for this book its very useful using


  2. Cahyo Sumarmo
    Aug 18, 2015

    i can not download in format pdf.would you help me?is another fault in download process?thaks


  3. Antony Arockiadas
    Jun 17, 2015

    Thanks for the E-book version


  4. saravanakumar.p
    Apr 27, 2015

    Thanks for sharing this e-book.


  5. Mustapha Adewuyi
    Jan 27, 2015

    Thanks for your contribution to the growth of the profession.


  6. Ali
    Jan 08, 2014

    Thank you Edvard for your contribution to the electrical engineering knowledge distribution


  7. Jean-Marc Biasse
    Dec 11, 2013

    A new version of MV Design Guide by Merlin Gerin has been issued.
    It is called now: Medium Voltage Technical Guide describing Basics for MV cubicle design by Schneider Electric. http://www2.schneider-electric.com/sites/corporate/en/customers/panelbuilders/technical-guides.page

    • Edvard
      Edvard
      Dec 11, 2013

      Thank you very much Jean-Marc! I’ll update this page with new version.


  8. habeb
    Nov 17, 2013

    Thank you for sharing this ebook.

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