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BS 3871 Miniature Circuit Breakers Let Through Energy

MG
Currently involved in a project where I need to do the energy let through calculations for existing circuit breakers to prove that the increased fault current even though within the breaking capacity of the MCB, damage will not occur to the final circuit cables.


In a nutshell, the following formula must be true I2t<k2S2 . In BS 60898 MCBs the I2t is provided by the manufacturers as these are energy limiting devices.


As these happen to be BS 3871 and in the absence of such data can I get your recommendations? Use a definite trip time of 10ms and plug that in the equation?


Thanks

Mike
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  • Former Community Member
    0 Former Community Member
    I should also add that if they are slightly more modern Loadmodule or Loadlimiter devices (particularly the latter at 9kA rating) they will have significantly better cut off characteristics at 3kA - something like 10,000A2S on a 10A Type C on a 3kA fault level


    Regards


    OMS
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  • Former Community Member
    0 Former Community Member
    I should also add that if they are slightly more modern Loadmodule or Loadlimiter devices (particularly the latter at 9kA rating) they will have significantly better cut off characteristics at 3kA - something like 10,000A2S on a 10A Type C on a 3kA fault level


    Regards


    OMS
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