Network structure example

Network structure example

Network structure:

Example network above consists of:

  • MV consumer substation;
  • Two MV ratings: 20 kV and 6 kV;
  • The main MV switchboard fed at 20 kV can be backed up by a set of four generators. It feeds:
    • An MV 20 kV network in a loop system comprising three secondary switchboards MV4, MV5 and MV6;
    • Two 20 kV/6kV transformers in a single line supply system;
  • The MV main switchboard is made up two bus sections fed at 6 kV by two sources with coupler;
  • It feeds three MV secondary switchboards and two 6 kV/LV transformers in a single line supply system;
  • the secondary switchboard MV2 is fed by two sources with coupler and is made up of two bus sections. It feeds two 6 kV motors and two 6 kV/LV transformers in a single line supply system;
  • the secondary switchboards MV1 and MV3 are fed by a single source. Each feeds a 6 kV/LV transformer and a 6 kV motor;
  • the main low voltage switchboard MLVS1 can be backed up by a generator;
  • the main low voltage switchboard MLVS2 is fed by two sources with coupler;
  • the main low voltage switchboard MLVS3 is fed by a single source;
  • the motor control centers 1 and 3 are fed by a single source; the motor control center 2 is fed by 2 sources with no coupler.

Reference: Protection of Electrical Networks - Christophe Prévé 

About Author //


Edvard Csanyi

Edvard - Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV high power busbar trunking (<6300A) in power substations, buildings and industry fascilities. Designing of LV/MV switchgears. Professional in AutoCAD programming and web-design. Present on


  1. Joaquín
    Sep 29, 2014

    I have two questions.

    Why MLVS2 (motor control center 2) doesn’t have some Emergency Generator or UPS system like “motor control center 1″ (or like MCC 3, only UPS)?

    Generator in MLVS1 can be coupled in 6kV MV system?

    Thank you! The best electrical page!

    • JK
      Mar 17, 2015

      Just my guessing
      1) motors connected in MLVS2 are not critical load so only primary selective bus design is enough for this loads.
      2) I think it can be moved to 6kV bus if the 6kV loads are critical

      My question is why UPS is not config as 2 primary source?

  2. Muralikrishnan
    Jun 21, 2014

    I like. And. Love EEP eee technical information thank-you sir

  3. firoz shaikh
    Jun 08, 2014

    Please give me power factor calculation tips

  4. mohammad ashibli
    Dec 13, 2013

    can give me software that calculate cable sizing for such grid

  5. Johnny
    Dec 12, 2013

    Excelente pagina…

  6. hamka
    Dec 11, 2013


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