1. Regulations
  2. title 46
  3. chapter I-i3
  4. part 111
  5. subpart 111.51
  6. § 111.51-3

View all text of Subpart 111.51 [§ 111.51-1 - § 111.51-5]

§ 111.51-3 - Short-circuit calculations for systems below 1500 kilowatts.

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