Fuseology Selection Guide Page 12 Fuseology Selection Guide

Fuseology Selection Guide www.littelfuse.com Littelfuse is at your service to help solve your electrical protection problems. When contacting Littelfuse sales engineers, please have all the requirements of your applications available. Requests for quotes or assistance in designing or selecting special types of circuit protection components for your particular applications are also welcome. In the absence of special requirements, Littelfuse reserves the right to make appropriate changes in design, process, and manufacturing location without prior notice. Fuse ratings and other performance criteria are evaluated under laboratory conditions and accptance criteria, as defined in one or more of the various fuse standards. It is important to understand these standards so that the fuse can be properly applied to circuit protection applications. UL/CSA/ANCE (Mexico) 248-14 FUSES FOR SUPPLEMENTARY OVERCURRENT PROTECTION (600 Volts, Maximum) (Previously UL 198G and CSA C22.2, No. 59) UL LISTED A UL Listed fuse meets all the requirements of the UL/ CSA/ANCE 248-14 Standard. Following are some of the requirements. UL ampere rating tests are conducted at 100%, 135%, and 200% of rated current. The fuse must carry 100% of its ampere rating and must stabilize at a temperature that does not exceed a 75C rise. The fuse must open at 135% of rated current within one hour. It also must open at 200% of rated current within 2 minutes for 0-30 ampere ratings and 4 minutes for 35-60 ampere ratings. The interrupting rating of a UL Listed fuse is 10,000 amperes AC minimum at 125 volts. Fuses rated at 250 volts may be listed as interrupting 10,000 amperes at 125 volts and, at least, the minimum values shown below at 250 volts. Ampere Rating of Fuse Interrupting Rating In Amperes Voltage Rating 0 to 1 35 250 VAC 1.1 to 3.5 100 250 VAC 3.6 to 10 200 250 VAC 0.1 to 15 750 250 VAC 15.1 to 30 1500 250 VAC Recognized Under the Component Program of Underwriters Laboratories The Recognized Components Program of UL is different from UL Listing. UL will test a fuse to a specification requested by the manufacturer. The test points can be different from the UL Listed requirements if the fuse has been designed for a specific application. Application approval is required by UL for fuses recognized under the Component Program. Standards UL 275 AUTOMOTIVE GLASS TUBE FUSES (32 Volts) UL LISTED UL ampere ratings tests are conducted at 110%, 135%, and 200%. Interrupting rating tests are not required. CSA Certification CSA Certification in Canada is equivalent to UL Listing in the United States. The Component Acceptance Program of CSA is equivalent to the Recognition Program at UL. METI (Japan Ministry of Economy, Trade and Industry) PS E METI APPROVAL METI approval in Japan is similar to UL Recognition in the United States. METI B has its own design standard and characteristics. INTERNATIONAL ELECTROTECHNICAL COMMISSION (IEC) Publication 60127, Parts 1, 2, 3, 4, 6 The IEC organization is different from UL and CSA, since IEC only writes specifications and does not certify. UL and CSA write the specifications, and are responsible for testing and certification. Certification to IEC specifications are given by such organizations as SEMKO (Swedish Institute of Testing and Approvals of Electrical Equipment) , BSI (British Standards Institute) and VDE (German Standard Insitute) E D V , as well as UL and CSA. IEC Publication 60127 defines three breaking capacity levels (interrupting rating). Low breaking capacity fuses must pass a test of 35 amperes or ten times rated current, whichever is greater, while enhanced breaking capacity fuses must pass a test of 150 amperes and high breaking capacity fuses must pass a test of 1500 amperes. 60127 Part 2 Sheet 1 - Type F Quick Acting, High Breaking Capacity Sheet 2 - Type F Quick Acting, Low Breaking Capacity Sheet 3 - Type T Time Lag, Low Breaking Capacity Sheet 4 - Style Fuses 1/41 1/4 Sheet 5 - Type T Time Lag, High Breaking Capacity Sheet 6 - Type T Time Lag, Enhanced Breaking Capacity The letters 'F' and 'T' represent the time-current characteristic of the fast-acting and time delay fuses. One of these letters will be marked on the end cap of the fuse. 12

Previous Page
Next Page