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Rated switching sequence according to IEC, O – t – CO – t’ – CO. (cf. opposite diagram):

O – Represents opening operation
CO – Represents closing operation followed immediately by an opening operation

Three rated operating sequences exist:

  • Slow: O – 3 min – CO – 3 min – CO
  • Fast 1: O – 0.3 s – CO – 3 min – CO
  • Fast 2: O – 0.3 s – CO – 15 s – CO

NOTE: Other sequences can be requested from manufacturer.

Close/Open cycle

Assumption: O order as soon as the circuit breaker is closed

Close/Open cycle of medium voltage circuit breaker
Close/Open cycle of medium voltage circuit breaker

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Automatic reclosing cycle

Assumption: C order as soon as the circuit breaker is open, (with time delay to achieve 0.3 s or 15 s or 3 min).

Automatic reclosing cycle of medium voltage circuit breaker
Automatic reclosing cycle of medium voltage circuit breaker
SOURCE: Schneider Electric – Medium Voltage Technical Guide

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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

5 Comments


  1. Erl Von Abong
    Jun 25, 2014

    Hello Sir,

    We have this rated operating sequence O-0.3s-CO-3min-CO VCB but our available unit have this rated operating sequence O-0.3s-CO-15s-CO.

    Is it OK to use?

    Please help.

    Thank you.


    • Kamal
      Sep 04, 2014

      I suppose,
      Requirement is O-0.3s-CO-3min-CO. And available VCB is O-0.3s-CO-15s-CO.
      15s VCB is suitable for autoreclosing application while 3 min VCB can’t.
      Although 15s VCB can be used in place of 3 min VCB with suitable delay timer in circuit of breaker.

      I hope it is the answer of your question.

      Regards
      Kamal


  2. sudamadhav
    Jan 07, 2013

    The article is quite not clear, i want a detailed explanation on this and where could i find articles or features or details about VCB’s. pls help

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