UL 248-1:2011 free download

UL 248-1:2011 free download Low-Voltage Fuses – Part 1 : General Requirements
1 General1.1 Scope
1.1.1 This Standard applies to low-voltage fuses rated 1000 V or less,AC and/or DC,with interruptingratings up to 300 kA (200 kA for Mexico). These fuses are intended to be used in accordance with theCanadian Electrical Code, Part (CEC), and the National Electrical Code, NFPA 70(NEC).
1.2 Object
1.2.1 This Standard and its subsequent Parts establish the characteristics，construction，operatingconditions，markings，and test conditions for each of the fuse classes so that initial investigation andfollow-up verification can be performed in an orderly manner.
2 Definitions
The following definitions apply in this Standard.
Note:The Clauses in Definitions,Clause 2, are numbered corresponding to the Clause numbers for definitions for thesimilar items contained in the International Electrotechnical Commission Publication 269-1: Low-voltage fuses，Part 1:General requirements.Some Clause numbers are omitted.
2.1 Fuse
2.1.3 Fuse
A protective device which opens a circuit during specified overcurrent conditions by means of a currentresponsive element.
2.1.3.1 Body
The part of the fuse which encloses the fuse elements and supports the contacts. Also referred to ascartridge, tube, or case.
2.1.3.2 Filler
Material used to fill a section or sections of a fuse.2.1.4 Contacts
The external metallic parts of the fuse used to complete the circuit. Also referred to as ferrules,caps,blades, or terminals.
2.1.5 Element
The fusible portion of the fuse which acts, during an overcurrent condition, to clear the circuit; also referredto as a link.
2.1.5.1 Renewal element
The part of a renewable fuse that is replaced after interruption to restore the fuse to operating condition.2.2 General terms
2.2.2 Current-limiting fuse
A fuse that, within a specified overcurrent range， limits the clearing time at rated voltage to an intervalequal to or less than the first major or symmetrical current loop duration; and limits the peak current to avalue less than the available peak current.
2.2.5.1 Ambient air temperature
The temperature of the air surrounding the fuse.Measurement of the ambient air temperature isconducted according to Clause 8.1.2.
2.2.7.1 Low melting point fuse
A fuse that will open in an ambient air temperature of 200°C when carrying 10 percent of rated current.
2.2.7.2 Microfuse
A supplemental fuse, the body of which has no principal dimension exceeding 1 0 mm (0.4 in), excluding the leads or terminals.
Note: Principal dimensions are length, width, height, and diameter.
2.2.7.3 Plug fuse
A screw-in type fuse for use in an Edison Base,Type C tamper-proof, or Type S tamper-proof fuseholder.
2.2.7.4 Renewable fuse A fuse which can be restored for service,after interruption, by the replacement of the renewal elements.
2.2.7.5 Supplemental fuse
A fuse intended only for supplementary overcurrent protection where branch-circuit protection is notrequired.
2.2.7.6 Time-delay fuse
A fuse capable of carrying a specified overcurrent for a specified minimum time. Time-delaycharacteristics are verified by the overload and operation tests in the relevant subsequent Parts for certainfuse classes.
2.2.7.7 Branch circuit fuse
A fuse which is suitable for protection of distribution systems, wiring, or equipment.Examples of branchcircuit fuses are Classes R,J,L, T, and CC. A supplemental fuse, intended to protect equipment only, isnot a branch circuit fuse.
2.2.8 Body size
The specified set of dimensions of fuses within a fuse class or system.Each individual size covers a givenrange of rated currents for which the specified dimensions of the fuse remain unchanged.
2.2.9 Homogeneous series of fuses
A series of fuse current ratings, within a given body size and of similar construction, such that one of theratings of the series may be taken as representative of the series itself.