W20

W20_C.qxd 28/4/03 10:19 am Page 1 Vitreous Enamelled Wirewound Resistors W20 Series Welwyn Components • CECC approved • Suitable for harsh environments • Impervious lead free vitreous enamel coating • Overload characteristics ideal for protection circuits • • High stability and reliability High power dissipation for size Electrical Data Commercial Power rating at 25°C Resistance range at 1% tolerance 2% tolerance 5% tolerance TCR (-55° to 200°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) Applicable to commercial and approved ranges Limiting element voltage Standard values Thermal impedance Ambient temperature range watts ohms ohms ohms pp/°C Style watts watts ohms ohms ohms ppm/°C W21 3.0 1R to 10K 0R5 to 10K 0R1 to 10K W215 W22 W23 W24 5.0 7.0 10.0 14.0 1R to 15K 1R to 22K 1R to 60K 1R to 100K 0R5 to 15K 0R5 to 22K 1R to 60K 1R to 100K 0R1 to 15K 0R1 to 22K 0R15 to 60K 0R2 to 100K Typically: .1G ohm >.1G ohm 500 min 500 min data available by request Application Notes 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 the resistor body and the printed circuit board or other components to ensure these are not over heated. Resistance is measured 6mm from body. 116 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. 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 be supplied preformed. Contact factory for details. 10 f1 6 Derating Curve f2 b f1 – f2 ≤ 1.4 mm 6 % of Rated Power 100 Standard Quantities Per Package 54 Type Ammo pack Reel Small box 25 70 200 315 W21 1000 1000 n/a b 63±2 73±2 73±2 W215 750 750 n/a W22 500 700 n/a W23 n/a n/a 50 W24 n/a n/a 25 0 Ambient temperature °C Type W21 W215 W22 © 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 86