The following short-circuit assumptions must be made for a system with an aggregate generating capacity below 1500 kilowatts, unless detailed computations in accordance with § 111.51-4 are submitted:
(a) The maximum short-circuit current of a direct current system must be assumed to be 10 times the aggregate normal rated generator currents plus 6 times the aggregate normal rated currents of all motors that may be in operation.
(b) The maximum asymmetrical short-circuit current for an alternating current system must be assumed to be 10 times the aggregate normal rated generator currents plus 4 times the aggregate normal rated currents of all motors that may be in operation.
(c) The average asymmetrical short circuit current for an alternating-current system must be assumed to be 8
1/2 times the aggregate normal rated generator currents plus 3
1/2 times the aggregate normal rated currents of all motors that may be in operation.
authority: 46 U.S.C. 3306,
3703; DHS Delegation No. 00170.1, Revision No. 01.2. Section 111.05-20 and Subpart 111.106 also issued under sec. 617, Pub. L. 111-281, 124 Stat. 2905
source: CGD 74-125A, 47 FR 15236, Apr. 8, 1982, unless otherwise noted.
cite as: 46 CFR 111.51-3