Cement Coated Wirewound Resistors Welwyn Components W30 Series • Values down to 10m ohms • Tolerance to 1% • Flameproof protection • Custom built to meet pulse requirements Electrical Data W31 Notes Power rating at 25°C watts 3.0 Power rating at 70°C watts 2.5 ohms 0R01 to 10K Resistance range TCR (-55 to 155°C) ppm/°C Resistance tolerance See below % Standard values 5 2 1 E24 series preferred Thermal impedance °C/watt Ambient temperature range °C Limiting element voltage -55 to 155 volts TCR ppm/°C Other values to special order 83 100 0.01 ohms <1000 0.033 ohms <500 0.091 ohms <200 10 ohms <150 10K ohms <100 Physical Data Maximum Dimensions (mm) and Weight (g) Type L max. D max. f min. d nom. Wt.nom. W31 13 5.6 22.75 0.8 1.0 d D L f Construction Marking A high quality ceramic substrate is assembled with interference fit end caps to which are welded the element winding and termination wires. The protection is then applied to the body, providing an effective seal which is impervious to moisture, shock, vibration, fungus and salt spray. W31 resistors are legend marked with type reference, resistance value and tolerance. Values are marked in accordance with IEC 62. The body and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. Terminations Material Strength Solderability Solvent Resistance Solder coated copper. The terminations meet the requirements of IEC 68.2.21. 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 © Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com Issue D · 07.06 99 Cement Coated Wirewound Resistors Welwyn Components W30 Series Performance Data Load: 1000 hrs 3 watts @ 25°C 1000 hrs 2.5 watts @ 70°C Dry heat: 1000 hrs at 200°C ∆R% Maximum Typical 5.0 + .001Ω 3.5 ∆R% 5.0 + .001Ω 3.5 ∆R% 5.0 + .001Ω 3.5 Derating from room temperature see derating curve Short term overload 10 x rated power for 5 seconds ∆R% 5.0 + .001Ω 1.0 Climatic ∆R% 5.0 + .001Ω 3.5 Long term damp heat: 56 days ∆R% 3.0 + .001Ω 1.0 Temperature rapid change ∆R% 2.0 + .001Ω 1.5 Resistance to solder heat ∆R% 5.0 + .001Ω 2.0 Vibration and bump ∆R% 5.0 + .001Ω Voltage proof volts Climatic category 55/200/56 2.0 500 min Pulse handling Data available by request % of Rated Power at 70 W31 Series Derating Curve 130 120 110 100 90 80 70 60 50 40 30 20 10 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 Temp Application Notes The terminations should not be bent closer than 1.6mm from the body, and the recommended minimum bend radius is 1.2mm. 10 Care must be taken when determining clearance between the resistor body and the P.C.B. or other components. Resistance is measured 6mm from body. f1 Standard Quantities Per Package Type W31 Ammo pack 1000 Reel 1000 © Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com 100 6 f1 – f2 ≤ 1.4 mm Packaging The standard method of packaging is taped in ammo packs. Can be provided on reels by request. W31 resistors can be supplied preformed. Contact factory for details. f2 63 6 Issue D · 07.06