Fuseology Selection Guide Page 13 Fuseology Selection Guide

www.littelfuse.com Fuseology Selection Guide UL/CSA/ANCE (Mexico) 248-14 vs. IEC 60127 Part 2 FUSE OPENING TIMES vs. METI/MITI Percent of Rating UL & CSA STD 248-14 IEC TYPE F Sheet 1 (*) IEC TYPE F Sheet 2 (*) IEC TYPE T Sheet 3 (*) IEC TYPE T Sheet 5 (*) METI/MITI 100 4Hr.Min. - - 130 - - - 1Hr.Min. 135 60 Minutes Max. - 150 - 60 Minutes Min. 60 Minutes Min. 60 Minutes Min. 60 Minutes Min. 160 - - - 1Hr.Max. 200 2 Minutes Max. - 2 Minutes Max. 210 - 30 Minutes Max. 30 Minutes Max. 2 Minutes Max. 30 Minutes Max. (*) Note: The IEC Specification is written up to 10.0A. Any components above these ratings are not recognized by the IEC (although the fuses may have similar opening characteristics). IEC also has opening time requirements at 275%, 400% and 1000%; however, the chart is used to show that fuses with the same ampere rating made to different specifications are not interchangeable. According to the IEC 60127 Standard, a one ampere-rated fuse can be operated at one ampere. A one ampere-rated fuse made to UL/CSA/ANCE 248-14 should not be operated at more than .75 ampere (25% derated - See RERATING section). METI B does not differentiate between fast acting and time delay characteristics. Publication IEC 60127-4 (Universal Modular Fuse-Links [UMF]) This part of IEC 60127-4 covers both PCB through-hole and surface mount fuses. This standard covers fuses rated 32, 63, 125, and 250 volts. This standard will be accepted by UL/CSA making it the first global fuse standard. This specification uses different fusing gates than IEC 60127-2; the gates used here are 125%, 200%, and 1000%. The fuses must not open in less than one hour at 125% of rated current and open within two minutes at 200% of rated current. The 1000% overload is used to determine the fuse characteristic. The opening time for each rating is listed below. Type FF : Less than 0.001 sec. Type F : From 0.001 - 0.01 sec. Type T : From 0.01 - 0.1 sec. Type TT : From 0.1 - 1.00 sec. These characteristics correlate to the terminology used in IEC 60127-1. Breaking capacity (interrupting rating) varies based on voltage rating. Parts rated at 32 & 63 volts must pass a test of 35 amperes or ten times rated current, whichever is greater. Parts rated at 125 volts must pass a test of 50 amperes or ten times rated current, whichever is greater. Parts rated at 250 volts are further defined as either low, intermediate or high breaking. The low breaking capacity fuses must pass a test of 100 amperes rated current, while intermediate breaking capacity fuses must pass a test of 500 amperes and high breaking capacity fuses must pass a test of 1500 amperes. MILITARY/FEDERAL STANDARDS MIL-PRF-15160 and MIL-PRF-23419 These specifications govern the construction and performance of fuses suitable primarily for military electronic applications. MIL-PRF-19207 This specification governs the construction and performance of fuseholders suitable for military applications. DSSC Drawing #87108 This drawing governs the construction and performance of .177" .570" (2AG size) cartridge fuses and axial lead versions suitable for military applications. DSSC #87108 designation is included in the fuse end cap marking. Standards (continued) A robust web-based tool to help circuit designers identify the optimal electronic fuses for their products. To use the Littelfuse iDesign tool, simply register to create a free online account at the iDesign Login. 13

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