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    Small Induction Motor Short Circuit Contribution

    I am looking for a good reference or paper on how long small <50HP 3 phase, low voltage (460V) induction motors typically contribute to short circuit. I found this paper which claims 1 to 4 cycles:

    http://apps.geindustrial.com/publibr...-Motor|generic

    Are there any other good references out there? Any help would be appreciated!
    Last edited by ish1284; 03-14-19, 02:01 PM.

    #2
    [COLOR=#333333]
    From https://forums.mikeholt.com/showthread.php?t=196850

    I've seen that assumption in some texts such as on page 389 of this text (middle-ish of the page)
    http://web.ecs.baylor.edu/faculty/le...pter7_GSO5.pdf

    Midway through this article -
    https://www.ecmweb.com/design/short-...lation-methods
    "The ANSI/IEEE method, which is described in IEEE Std. C37.010-1979 and its revision in 1999, is used for high-voltage (above 100V) equipment. It calls for determining the momentary network fault impedance, which makes it possible to calculate the close and latch rating of the breaker. It also calls for identifying the interrupting network fault impedance, which makes it possible to calculate the interrupting duty of the breaker. The interrupting network fault impedance value differs from the momentary network fault impedance value in that the impedance increases from the subtransient to transient level.The IEEE standard permits the exclusion of all 3-phase induction motors below 50 hp and all single-phase motors. Hence, no reactance adjustment is needed for these motors. The Chart at left clarifies the ANSI/IEEE procedure."
    [/COLOR]
    Ron

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