WA84F

WA84F_C.qxd 28/4/03 10:51 am Page 1 Fusible Wirewound Resistors WA84F Welwyn Components • Predictable fusing characteristics • Flameproof protection • Suitable for pulse and fuse applications Electrical Data WA84F Power rating at 25°C Power rating at 70°C Resistance range Limiting element voltage Isolation voltage TCR (-55°C to 155°C) Resistance tolerance Values Thermal impedance Ambient temperature range °C/watt °C watts watts ohms volts volts ppm/°C % 2.0 1.6 0R2 to 30R 100 350 ≤1 Ω:350 >1 Ω:100 5 E24 preferred 90 - 55 to 155 Physical Data Dimensions (mm) and Weight (g) PCB mounting centres 20.3 Min bend radius 1.2 Type WA84F L max 14.5 D max 5.2 f min 23.6 d nom 0.8 Wt.nom 1.1 d D L f 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. Solvent Resistance The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. Terminations Material Strength Solder-coated copper wire The terminations meet the requirements of IEC 68.2.21. 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. 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. 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. A subsidiary of TT electronics plc Issue C · 04.03 © 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 170 WA84F_C.qxd 28/4/03 10:51 am Page 2 Fusible Wirewound Resistors WA84F Welwyn Components Performance Data Maximum Load at rated power: 1000 hrs at 25 or 70°C Dry heat: 1000 hrs at 200°C Derating from rated power at 25°C Short term overload - 2.5 x rated power for 5 seconds D.H.S.S. Climatic Pulse handling ∆ R% ∆ R% ∆ R% ∆ R% ∆ R% 5.0 5.0 zero at 275°C 5.0 5.0 5.0 Data available by request 2.0 2.0 1.0 Typical 3.0 3.0 Fusing characteristics for constant voltage Max. time to fuse (seconds) 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0 0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 for R20 to 30R Fusing characteristics for constant current Max. time to fuse (seconds) 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0 0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 for R20 to 2R for 2R1 to 30R Multiple of rated power Multiple of rated power Packaging % of Rated Power at 70°C 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. Figure 2 130 120 110 100 90 80 70 60 50 40 30 20 10 0 20 WA84F Series Derating Curve 40 60 80 100 120 140 160 180 200 220 240 260 280 Temp°C 10 f1 6 67 f2 6 Body Location f1 – f2 ≤ 1.4 mm Standard Quantities Per Package Type Reel Large ammo pack WA84F 1000 1000 Type WA84F b 67 c 10 © 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 · 04.03 171