Aluminium Housed Wirewound Resistors Welwyn Components WH Series • High power dissipation for size • All welded construction • Suitable for severe environments • Designed for excellent thermal conductivity to heatsink Electrical Data WH5 WH10 WH25 WH50 Notes Power rating at 25°C watts 10 15 25 50* Mounted on standard heatsink Resistance range ohms 0R01 to 10K 0R01 to 20K 0R01 to 44K 0R015 to 120K TCR (-55° to 200°C) ppm/°C Resistance tolerance % Low value limits ohms ≥ to <100 : ±50 <10Ω : ±75 ≥100Ω : ±25 1, 2, 5, 10 1 at 1% 0.5 at 2% 0.05 at 5% 0.01 at 10% Approved CECC 40203 - 006 AA BA CA DA Power rating at 25°C watts 10 15 25 40 ohms 0.05 to 3.4k 0.05 to 15k 0.05 to 33k 0.05 to 82k Resistance range TCR (-55° to 200°C) ppm/°C Resistance tolerance % Low value limits ≥5Ω ≤ 10Ω ± 100 volts 1 at 1% 150 Standard values >10Ω ± 50 0.5 at 2% 250 0.05 at 5% 500 WH50 0.015 at 10% 1250 E24 preferred range Thermal impedance °C/watt Ambient temperature range Mounted on standard heatsink 1, 2, 5 ohms Limiting element voltage WH50 0.015 at 10% 16.0 10.0 °C 6.0 Other values to special order 3.5 Mounted on standard heatsink -55 to 200 *For load at maximum rating mount on heatsink 30.5 cm x 30.5 cm x 1.5 mm Construction Marking Cap and lead assemblies are fitted to a high purity ceramic substrate. The resistive element is wound onto the substrate and welded to the caps. The wound rod is then moulded and fitted into an aluminium housing to give optimum stability and reliability. The resistors are legend marked with type reference, resistance value and tolerance which will withstand all accepted industrial cleaning fluids. Values are marked in accordance with IEC 62. Terminations Material Strength Solderability Solder dipped, copper clad steel wire. The terminations meet the requirements of IEC 68.2.21 The terminations meet the requirements of IEC 115-1, Clause 4.17.3.2 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: [email protected] · Website: www.welwyn-tt.com A subsidiary of TT electronics plc Issue D · 03.06 107 Aluminium Housed Wirewound Resistors Welwyn Components WH Series Physical Data Dimensions (mm) Type A B C E F Max ±0.3 ±0.3 Min Max WH5 30.0 12.4 11.3 1.9 17 WH10 36.5 15.9 14.3 1.9 21 WH25 51.0 19.8 18.3 2.8 28 WH50 72.5 21.4 39.7 2.8 30 G H L M N Type Max Dia ±0.2 Max ±0.5 Max WH5 9 2.4 17.0 4.3 1.8 WH10 11 2.4 21.0 5.2 2.2 WH25 15 3.3 29.0 7.2 2.6 WH50 16 3.3 51.0 7.9 2.6 Performance Data CECC Actual Maximum Typical Load at commercial rating: 1000 hrs at 25°C ∆R % 1.0 1.0 0.4 Load at CECC rating: 1000 hours at 25°C ∆R % 1.0 1.0 0.4 Dry heat: 1000 hours at 200°C ∆R % 1.0 1.0 0.4 1.0 1.0 0.2 1.0 1.0 0.4 0.2 Derating from 25°C Zero at 200°C Short term overload ∆R % Climatic sequence ∆R % Climatic category 55/200/56 Long term damp heat ∆R % 1.0 0.5 Temperature rapid change ∆R % 0.25 0.25 0.1 Resistance to solder heat ∆R % 0.25 0.25 0.05 Vibration and bump 0-.025 ∆R % 0.25 0.25 Noise (in decade of frequency) µV/V Not specified zero zero Insulation resistance. ohms >1Gohm >20Tohm >100Gohm volts AC peak 1000 min 1500 min See application volts AC peak 2000 min 3000 min notes Isolation voltage : WH5 and 10 : WH25 and 50 Pulse handling Data available by request © 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 108 Notes 40203-006 Issue D · 03.06 Aluminium Housed Wirewound Resistors Welwyn Components WH Series Application Notes Graph 1 CECC 40203-006 AA (WH5) BA (WH10) CA (WH25) L W H Reference cm cm cm area sq. cm 15.5 10 5 410 18 DA (WH50) 13 5 544 Aluminium thickness 1mm Reference chassis CECC 40 STYLE 50 Maximum Dissipation (Watts) Reference aluminium heatsink dimension 40 5C T2 544cm2 NA 0C 7 T S I A ON DD I T E A T SIP RA 25C DIS ED RAT 70C DA IO AT SIP 30 20 25C 70C 25C 70C 10 410cm 5 10 50 100 CA BA AA 2 500 1000 Heatsink Surface Area (cm2) H L W WH50 only To load at maximum commercial rating (50W) mount on heatsink 30.5cm x 30.5cm x 1.5mm. Derating must be applied when resistors are mounted on a heat sink of smaller dimensions than defined in Graph 1. It is recommended that the resistor base should be coated with heatsink compound before mounting to obtain the stated operating characteristics. The heatsink compound increases thermal conductivity to the heatsink. After soldering care should be taken to ensure that there are no flux residues on the moulding compound, otherwise insulation resistance will be reduced. Packaging Resistors are packed in plastic bags and boxed for maximum protection. © 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 · 03.06 109