UL 248-12:2011 pdf download – Low-Voltage Fuses – Part 12: Class R Fuses.
NOTEThe Parr is wtend to he read togeTher with Me Standard lo.r Low-Voltage Fuses – I: General Requlremenls.
hereafter referred toes Pert 1. The nm?bering of the Clauses ui this Pan corresponds to ithe numbered Claus5s Afl Pafl
1. The req.Eemen1s of Part app.ty unless modthed t’ This Part For Clauses nd shobw, befow, refer to the Standard for
Low- Voltage Fuses – Part 1: General Peou#e,nents, NUX 9248l-ANCE • CAN CSA C22.2 No 248 1-li. Elt.
1.1 Scope
This Part applies to Class R fuses rated 600 A ci less and either 250 or 600 V ac. DC ratings are optional.
4 Classification
Class R fuses are non-renewable and current-limiting, with an interrupting rating of 200,000 A. Class R fuses are divided into sub-classes RKI and RK5 and are physically interchangeable for me same current and voltage ratings. Class RK1 fuses have lower specthed maximum peak let-through current and clearing 12t characteristics. Each of the voltage ratings, 250 and 600 V ac, is divided into six body sizes. The maximum current rating, In, for each size Is specified in this Standard. Time-delay ratings are optional.
5 Characteristics
52 Voltage rating
Fix AC, the rating shall be 250 or 600 V ac in accordance with dimensions shown in Figures A and B.
The DC voltage rating may be different from the AC rating.
5.3 Current rating
Refer to Figure A for range of current ratings in each body size for each voltage rating.
5.5 Interrupting rating
For AC, 200,000 A, or 300,000 A at the manufacturers option (300.000 not applicable in Mexico),
For DC. the preterred ratings are 10.000. 20.000, 50,000, 100.000, 150.000, 200,000, or 300,000A.
5.6 Peak let-through current and clearing 12t characteristics
Maximum values ol peak tet-through current and clearing 12t Class RK1 and Class RK5 fuses are given in Table A (see L5.3). Peak let.through currents shall not exceed the levels defined by the appropriate Let Through Function specified in Table A, as verified through measurement of peak let-through currents at 25. 50. 100, 200. and, it applicable, 300 kA.
Clearing 12t values recorded shall not exceed the limits specified in Table A as verified through measurement of cleanng l2t values at 25, 50. 100, 200, and. if applicable, 300 kA.