UL 248-9:2005 pdf download – Low-Voltage Fuses一Part 9: Class K Fuses.
1 General
This Part is intended to be read together with the Standard for Low-Voltage Fuses — Part I: General Requirements. hereafter referred to as Parr 1. The numbering of the Clauses in this Part correspond to like numbered Clauses in Parr I. The requirements of Part I apply unless modified by this Parr. For Clauses nor shown below, refer to the Standard for Low-Voltage Fuses — Parr 1:
Gcnenl Requirements, NMX-J-009/248/9-2000-ANCE . CAN/CSA C22.2 No. 248.1 • UL 248-I.
1.1 Scope
This Part applies to Class K fuses rated 600 A or less and either 250 or 600 V ac. DC ratings are optional.
4 Classification
Class K fuses are non-renewable, with interrupting ratings of 50,000, 100,000, or 200,000 A. Class K fuses are divided into sub-classes K-I, K-5, and K-9 which are physically interchangeable with each other (and Class H fuses) for the same current and voltage ratings. Each sub-class has specified limits of peak let-through current and clearing 12t characteristics. K-I has the lowest limits (most current-limiting), K-5 higher, and K-9 highest. Each of the voltage ratings, 250 and 600 V ac, is divided into six body sizes. The maximum current rating, l,, for each size is specified in this Part. Time-delay ratings are optional.
In Canada, 250V ac fuses rated 15 — 60 A shall have a low melting point “P” (“D” for time delay) characteristic. See sub-clauses 6.1 and 9.2.
5 Characteristics
5.2 Voltage rating
For AC, the rating shall be 250 or 600 V ac in accordance with dimensions shown in Figure A. The DC voltage rating may be different from the AC rating.
5.3 Current rating
Refer to Figures A and B for range of current ratings in each body size for each voltage rating.
6 Marking
6.1 Marking of fuses
In addition to the requirements in Part 1: Fuses with a low me lting point characte ristic for Canada, shall be marked with a “P”, or with a “D” for time de lay.
g) The fuse shall not be marked “Curre nt Limiting.
7 Construction
7.1 Dimensions
Fuse dimensions are shown in Figures A and B.