Forums » Electrical Engineering

800A circuit breaker

    • 2 posts
    August 17, 2019 10:21 AM PDT

    I want to double check with you guys after looking some catalogs:

    800A circuit breaker at 12kV network, Imax is 65kA. Is this value the rms value or the peak value?

    This post was edited by Roderick Barlow at August 17, 2019 10:28 AM PDT
    • 156 posts
    August 17, 2019 11:06 AM PDT

    I think, it is a symmetrical value which occurs during steady state. let's see others comments.

    • 103 posts
    August 18, 2019 5:26 AM PDT

    Its an RMS value.  The maximum symmetrical short circuit current the breaker can interrupt at maximum voltage.

    The close & latch is usually a peak value.



    • 33 posts
    August 18, 2019 11:13 PM PDT

    I’’k: rms value of the initial symmetrical current

    Ib: rms value of the symmetrical current interrupted by the switching device when the first pole opens at tmin (minimum delay)

    Ik: rms value of the steady-state symmetrical current

    Ip: maximum instantaneous value of the current at the first peak

    IDC: DC value of the current

    • 17 posts
    August 22, 2019 10:33 AM PDT

    I reckon that it depends on the fuse norm. The new codes always provide the rms value of the steady-state symetrical current and the code stablish to do a test that the device it is not going to be destroyed with the value I''k. Sometimes the code tell you to support 0.5s the thermic force.