SP20F

General-Purpose Failsafe Moulded Wirewound Resistors SP20/SP20F Series Welwyn Components • Drop-in replacement for BW20/BW20F • Predictable fusing characteristics • 1 watt rated with 1/2 watt dimensions • 0.1 ohm to 1200 ohms • Weldable and solderable magnetic leads Electrical Data Type EIA RS-344 Style MIL-R-11 Style Resistance Range Tolerance Power rating ohms % watts 1 at 50°C 0.75 at 70°C 0.5 at 100°C Derating to 0 at 160°C Maximum continuous working voltage Minimum insulation resistance Minimum dielectric withstanding volts Reduced pressure Hotspot temperature rise Current noise dry wet ATM RMS √PR 10,000 Meg 100 Meg 700V 450V 120°C at 1 watt Negligible 0R1 to 1k2 ±5, ±10 1 at 50°C 0.75 at 70°C Derating to 0 at 160°C SP20 CRU 1 RC20/RC32 0R1 to 1k SP20F Physical Data Dimensions (mm) Type SP20 SP20F L 9.91±0.25 9.91±0.25 D 3.56±0.20 3.56±0.20 d 0.813±0.05 0.813±0.05 f 38.1±3.2 38.1±3.2 d D L f Resistive Element All resistor types have resistance alloy winding on a braided fibreglass substrate. Intermediate silicone coatings are used to enhance processibility and to provide protection to the resistive element. Encapsulation The SP20 and SP20F are encapsulated utilizing a compression molded phenolic plastic material. The SP20F has a flame resistance coating applied over the resistive element to provide flammmability protection when destructive overloads may occur. Termination The SP20 and SP20F resistors are terminated using an alloy coated copper flashed steel lead welded to a cap of the same material. This termination assembly is mechanically crimped, utilizing an improved crimp design, to the resistive element. Marking All products are marked utilizing heat and solvent resistant colour code bands consistent with EIA/MIL requirements. The first band is double width to designate wirewound construction. A fifth band, blue in colour, is used for flameproof identification. 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 Issue B · 03.02 © 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 95 General-Purpose Failsafe Moulded Wirewound Resistors SP20/SP20F Series Welwyn Components Performance Data Test Temperature coefficient (ppm) Dielectric withstanding voltage Momentary overload Low temperature operation Temperature cycle Humidity Load life Terminal strength Resistance to solder heat ppm/°C RMS % % % % % % % SP20