fusible wirewound resistors WA84F predictable fusing characteristics flameproof protection suitable for pulse and fuse applications WA84F power rating at 25? watts 2.0 power rating at 70? watts 1.6 resistance range ohms 0r2 to 30r limiting element voltage volts 100 isolation voltage volts 350 tcr (-55? to 155?) ppm/? 1 ? :350 >1 ? :100 resistance tolerance % 5 values e24 preferred thermal impedance ?/watt 90 ambient temperature range ? - 55 to 155 general note welwyn components reserves the right to make changes in product specification without notice or liability. all information is subject to welwyn s own data and is considered accurate at time of going to print. ?welwyn components limited ?bedlington, northumberland ne22 7aa, uk telephone: +44 (0) 1670 822181 ?facsimile: +44 (0) 1670 829465 ?email: info@welwyn-tt.com ?website: www.welwyn-tt.com electrical data issue c ?04.03 a subsidiary of tt electronics plc welwyn components 170 construction a high purity ceramic substrate is assembled with interference fit end caps to which are welded the termination wires. the resistive element is wound on the substrate and welded to the caps. cement protection is applied to the resistor body before marking with indelible ink. marking resistors are colour coded with five bands. four of the bands are used to indicate value and tolerance, with iec62 colours being used. a fifth yellow band denotes fusibility. solvent resistance the body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. terminations material solder-coated copper wire strength the terminations meet the requirements of iec 68.2.21. solderability the terminations meet the requirements of iec 115-1, clause 4. 17. 3. 2. flammability the resistor coating will not burn under any condition of applied temperature or component overload. dimensions (mm) and weight (g) pcb min mounting bend type l max d max f min d nom centres radius wt.nom WA84F 14.5 5.2 23.6 0.8 20.3 1.2 1.1 physical data l d f d WA84F_c.qxd 28/4/03 10:51 am page 1
fusible wirewound resistors WA84F ?welwyn components limited bedlington, northumberland ne22 7aa, uk telephone: +44 (0) 1670 822181 ?facsimile: +44 (0) 1670 829465 ?email: info@welwyn-tt.com ?website: www.welwyn-tt.com issue c ?04.03 welwyn components 171 67 f 1 f 2 6 6 10 body location f 1 ?f 2 1.4 mm packaging the standard method of packaging is taped in ammo packs. can be provided on reels by request. the critical dimensions are shown in figure 2. component wires will not protrude beyond the outside edge of the tapes. alternative packaging available by special request are detailed in table opposite. 0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0 multiple of rated power fusing characteristics for constant voltage max. time to fuse (seconds) for r20 to 30r 0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0 multiple of rated power fusing characteristics for constant current max. time to fuse (seconds) for 2r1 to 30r for r20 to 2r 20 40 60 80 100 120 140 160 180 200 220 240 260 280 130 120 110 100 90 80 70 60 50 40 30 20 10 0 te m p c WA84F series derating curve % of rated power at 70 c figure 2 maximum typical load at rated power: 1000 hrs at 25 or 70? ? r% 5.0 3.0 dry heat: 1000 hrs at 200? ? r% 5.0 3.0 derating from rated power at 25? zero at 275? short term overload - 2.5 x rated power for 5 seconds ? r% 5.0 2.0 d.h.s.s. ? r% 5.0 2.0 climatic ? r% 5.0 1.0 pulse handling data available by request performance data type WA84F reel 1000 large ammo pack 1000 standard quantities per package type b c WA84F 67 10 WA84F_c.qxd 28/4/03 10:51 am page 2
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