Vitreous Enamelled Wirewound Resistors W20 SERIES ● All welded construction ● High purity ceramic substrate ● Impervious lead free vitreous enamel coating ● High power dissipation for size ● High stability and reliability ● Suitable for harsh environments ● Overload characteristics ideal for protection circuits Electrical Data Commercial Power rating at 25°C Resistance range at 1% tolerance 2% tolerance 5% tolerance watts ohms ohms ohms pp/°C Approved BS CECC 40-201-002 Power rating at 25°C Power rating at 70°C Resistance range at 1% tolerance 2% tolerance 5% tolerance TCR (-55° to 200°C) Style watts watts ohms ohms ohms ppm/°C TCR (-55° to 200°C) Applicable to commercial and approved ranges Limiting element voltage volts Standard values Thermal impedance °C/watt Ambient temperature range °C W21 3.0 1 to 10k 0.5 to 10k 0.1 to 10k W215 5.0 1 to 15k 0.5 to 15k 0.1 to 15k Typically: <+75 W22 7.0 1 to 22k 0.5 to 22k 0.1 to 22k W23 W24 10.0 14.0 1 to 60k 1 to 100k 1 to 60k 1 to 100k 0.15 to 60k 0.2 to 100k Maximum: +200 JB HB KB LB MB 2.9 5.0 7.0 10.0 14.0 2.5 4.3 6.0 9.0 12.0 1 to 10k 1 to 15k 1 to 20k 1 to 56k 1 to 100k 0.5 to 10k 0.5 to 15k 0.5 to 20k 1 to 56k 1 to 100k 0.1 to 10k 0.1 to 15k 0.1 to 20k 0.15 to 56k 0.2 to 100k ≥5 ohms < 10 ohms: ±400 ≥10 ohms: ±200 100 160 200 500 E24 preferred. Other values to special order 88 58 44 29 -55 to 200 750 22 Physical Data Dimensions Type W21 W215 W22 W23 W24 (mm) & weight (g) L max D max 12.7 5.6 22.0 7.0 22.0 8.0 38.0 8.0 53.5 8.0 f min 22.75 23.1 23.1 - Temperature Rise °C W215 W24 W23 W22 300 200 100 0 0 5 10 15 Dissipation – Watts Wt.nom 1 2 2 3.5 5 d dia 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; the vitreous enamel protective coating is then applied. 400 W21 d nom 0.8 0.8 0.8 0.8 0.8 20 TERMINATIONS Material Copper clad steel wire, nickel plated and solder-coated. 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. Length W23’s and W24’s are not supplied on tape. Minimum lead length is 30 mm. MARKING The resistors are legend marked with type reference, resistance value and tolerance. Values are marked in accordance with IEC 62. SOLVENT RESISTANCE The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. 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 Vitreous Enamelled Wirewound Resistors W20 SERIES Performance Data CECC 40201-002 Requirements Load at commercial rating: 1000 hrs at 25°c Load at CECC rating: 1000 hours at 25°c Dry heat: 1000 hours at 200°c Shelf life: 12 months at room temperature Derating Short term overload Climatic Climatic category Long term damp heat Temperature rapid change Resistance to solder heat Vibration and bump Noise (in decade of frequency) Robustness Insulation resistance Voltage Proof Pulse handling data ∆R% ∆R% ∆R% ∆R% 5 5 not specified ∆R% ∆R% ∆R% ∆R% ∆R% ∆R% ∆R% µv/v ∆R% Ohms volts 1 5 55/200/56 5 1 1 1 not specified 1 not specified not specified APPLICATION NOTES ACTUAL PERFORMANCE Maximum Typical 5 3.5 5 3.5 2 1 0.03 0.02 see derating curve 1.0 0.2 0.5 0.2 0.05 0.02 0.5 0.2 0.25 0.03 0.25 0.05 zero zero 0.4 0.05 >.1G ohm >.1G ohm 500 min 500 min available by request Derating Curve The termination should not be bent closer than 1.6mm from the body, and the recommended minimum bend radius is 1.2mm. The terminations are solderable to within 4mm from the body. When cold, vitreous enamel has excellent insulation resistance. In common with all insulants the specific resistance of the enamel decreases with increase in temperature. Therefore, resistors operated at near maximum temperature cannot be classed as insulated and should not be used in contact with any conducting material. Care must be taken when determining clearance distance between % of Rated Power 116 100 54 0 25 70 200 315 Ambient temperature °C the resistor body and the printed circuit board or other components to ensure these are not over heated. Resistance is measured 6mm from body. PACKAGING For W21 and W215 the standard method of packaging is taped in Ammo Packs. For W22 the standard method of packaging is taped and reeled. 10 ± 0.5 Alternatives available by special request are detailed in the table below. W23’s and W24’s are available only as loose packed in boxes. W series resistors can bbe supplied preformed. Contact factory for details. f1 6 f2 A f1 – f2 ≤ 1.4 mm 6 STANDARD QUANTITIES PER PACKAGE Type Ammo Pack Reel Small Box W21 W215 W22 1000 750 500 1000 750 700 N/A N/A N/A W23 N/A N/A 50 W24 N/A N/A 25 Type W21 W215 W22 A 63±2 73±2 73±2 © 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