Chassis Mounting Wirewould Resistors WH SERIES ● High quality ceramic substrate ● All welded construction ● Anodised extruded aluminium case ● High power dissipation for size ● Suitable for severe environments ● Designed for excellent thermal conductivity to heatsink Electrical Data Power rating at 25°C watts Resistance range TCR (-55° to 200°C) Resistance tolerance Low value limits ohms ppm/°C % ohms APPROVED CECC 40203 - 006 Power rating at 25°C watts Resistance range TCR (-55° to 200°C) Resistance tolerance Low value limits Limiting element voltage Standard values Thermal impedance ohms ppm/°C % ohms volts °C/watt WH5 10 EH10 15 WH25 25 WH50 50* 0.01 to 10k 0.01 to 20k 0.01 to 44k 0.015 to 120k <10Ω : ±75 ≥ to <100 : ±50 ≥100Ω : ±25 1, 2, 5, 10 1 at 1% 0.5 at 2% 0.05 at 5% 0.01 at 10% AA 10 BA 15 CA 25 DA 40 NOTES Mounted on standard heatsink WH50 0.015 at 10% Mounted on standard heatsink 0.05 to 3.4k 0.05 to 15k 0.05 to 33k 0.05 to 82k ≥5Ω ≤ 10Ω ± 100 >10Ω ± 50 1, 2, 5 1 at 1% 0.5 at 2% 0.05 at 5% 150 16.0 250 500 E24 preferred range 10.0 Operating temperature range °C 6.0 1250 3.5 Other values to special order 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 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. TERMINATIONS Material Solder dipped, copper clad steel 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 MARKING The resistors are legend marked with type reference, resistance value and tolerance. Values are marked in accordance with IEC 62. SOLVENT RESISTANCE Resistor and marking withstand all accepted industrial cleaning fluids. 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, England Tel: 01670 822181 Fax: 01670 829465 Web: http://www.Welwyn-TT.co.uk Issue A 07/99 Chassis Mounting Wirewound Resistors WH SERIES Physical Data DIMENSIONS (MM) Type A B Max ±0.3 WH5 30.0 12.4 WH10 36.5 15.9 WH25 51.0 19.8 WH50 72.5 21.4 Type G H Max Dia ±0.2 WH5 9 2.4 WH10 11 2.4 WH25 15 3.3 WH50 16 3.3 C ±0.3 11.3 14.3 18.3 39.7 L Max 17.0 21.0 29.0 51.0 E Min 1.9 1.9 2.8 2.8 M ±0.5 4.3 5.2 7.2 7.9 F Max 17 21 28 30 N Max 1.8 2.2 2.6 2.6 Performance Data Load at commercial rating: 1000 hrs at 25°C ∆R % Load at CECC rating: 1000 hours at 25°C ∆R % Dry heat: 100 hours at 200°C ∆R % Derating from 25°C Short term overload ∆R % Climatic sequence ∆R % Climatic category Long term damp heat ∆R % Temperature rapid change ∆R % Resistance to solder heat ∆R % Vibration and bump ∆R % Noise (in decade of frequency) µV/V Insulation resistance. ohms Isolation voltage : WH5 and 10 volts AC peak : WH25 and 50 volts AC peak CECC ACTUAL 40203-006 MAXIMUM TYPICAL 1.0 1.0 0.4 1.0 1.0 0.4 1.0 1.0 0.4 Zero at 200°C 1.0 1.0 0.2 1.0 1.0 0.4 55/200/56 1.0 0.5 0.2 0.25 0.25 0.1 0.25 0.25 0.05 0.25 0.25 0-.025 Not specified zero zero >1Gohm >20Tohm >100Gohm 1000 min 1500 min 2000 min 3000 min NOTES See application notes © Welwyn Components Limited Bedlington, Northumberland NE22 7AA, England Tel: 01670 822181 Fax: 01670 829465 Web: http://www.Welwyn-TT.co.uk Issue A 07/99 Chassis Mounting Wirewound Resistors WH SERIES APPLICATION NOTES L W H REFERENCE CM CM CM AREA SQ. CM AA, BA 15.5 10 5 410 CA, DA 18 13 5 544 Aluminium thickness 1mm Reference chassis MAXIMUM DISSIPATION (WATTS) CECC 40203-006 CECC 40 STYLE 50 Reference aluminium heatsink dimension 40 °C 25 AT 544cm2 N IO AT C P I 70° ISS AT DD ION T E A T SIP RA 25°C DIS ED RAT 70°C 30 20 CA CA 25°C 70°C BA 25°C 70°C AA 10 410cm2 H 5 10 50 100 500 1000 HEATSINK SURFACE AREA (cm2) L W Derating must be applied when resistors are mounted on a heat sink of smaller dimensions than defined in the table for reference heatsink. WH50 ONLY To load at maximum commercial rating (50W) mount on heatsink 30.5cm x 30.5cm x 1.5mm. It is recommended that the resistor base should be coated with silicone grease before mounting to obtain the stated operating characteristics. The grease 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. 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, England Tel: 01670 822181 Fax: 01670 829465 Web: http://www.Welwyn-TT.co.uk Issue A 07/99