General-Purpose Failsafe Moulded Wirewound Resistors Welwyn Components SPH/SPF Series • Drop-in replacement for BWH/BWF • 2 watt rated with 1 watt dimensions • ±5%, ±10% tolerance • 0.1 ohm to 2400 ohms • TCR’s as low as ±150 ppm/°C standard (custom TC’s available) • Weldable and solderable leads Electrical Data Type S PH SPF EIA RS-344 Style CRU2 MIL-R-11 Style RC32/RC42 Resistance ohms Tolerance 0R1 to 2k4 0R1 to 1k % Power rating ±5, ±10 watts 2 at 70°C 1 at 115°C Derating to 0 at 160°C Maximum continuous working voltage √PR Minimum insulation resistance dry 10,000 Meg wet 100 Meg Minimum dielectric withstanding volts ATM 1000V Reduced pressure RMS 625V watts 145°C at 2 watts Hotspot temperature rise Current noise Negligible Physical Data Dimensions (mm) Type L D d f SPH 14.3 ±0.25 5.72 ±0.20 0.813 ±0.05 38.1 ±3.2 SPF 14.3 ±0.25 5.72 ±0.20 0.813 ±0.05 38.1 ±3.2 d D L f Resistive Element Encapsulation 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. The SPH and SPF are encapsulated utilizing a compression moulded phenolic plastic material. The SPF has a flameresistance coating applied over the resistive element to provide flammmability protection when destructive overloads may occur. Termination Marking The SPH and SPF 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. 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. © 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 B · 03.02 93 General-Purpose Failsafe Moulded Wirewound Resistors Welwyn Components SPH/SPF Series Performance Data SP H Temperature coefficient (ppm)* ohms S PF 0.1 - 0.16 ±1000 0.10 ±1700 0.18 - 0.68 ±800 0.11 - 0.16 ±1000 0.75 -2400 ±400 0.18 - 0.68 ±800 0.75 - 1000 ±400 Dielectric withstanding voltage RMS 1000V Momentary overload % Low temperature operation % 5 5 Temperature cycle % 5 Humidity % 5 Load life % 5 Terminal strength % 5 Resistance to solder heat % 5 *All ppm levels listed are maximum SPF Power Derating Power (watts) Power (watts) SPH Power Derating Ambient Temperature (°C) Ambient Temperature (°C) SPH & SFF Temperature Rise Power (watts) 0.1 ohm 1 ohm 10 ohm 100 ohm Temp (°C) SPF Typical Fusing 1000 ohm Time (seconds) Power Input (watts) Packaging Resistors are supplied taped and reel. 4,000 pcs per reel. © 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 94 Issue B · 03.02