WFF WELWYN | Alldatasheet
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- Low power fusing Predictable fusing characteristics Flameproof protection WFF1/4 WFF1/2 WFF1 15.052.0sttawC˚07 ta gnitar rewoP 5K1 - 2R0K72 - 01R0K01 - 1R0smhoegnar ecnatsiseR 053053052stlovegatlov tnemele gnitimiL 052C˚/mppRCT 5%ecnarelot ecnatsiseR Standard values E24 preferred 001021051ttaw/C˚ecnadepmi lamrehT 551 ot 55-C˚egnar erutarepmet tneibmA 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: info@welwyn-tt.com · Website: www.welwyn-tt.com Electrical Data Issue D · 03.06 A subsidiary of TT electronics plc Welwyn Components 161 Construction The metal film is deposited on a high purity ceramic rod. End caps are force fitted and termination wires welded to the caps. The resistive film is adjusted to the required value by a special helical cut. A fuse aid coating is then applied. Finally a cement protection is applied to the resistor body prior to marking with indelible ink. Terminations Material Solder-coated copper wire. Strength The terminations meet the requirements of IEC68.2.21. Solderability The terminations meet the requirements of IEC 115-1 Clause 4.17.3.2. Marking Resistors are colour coded with 5 bands. Four of the bands are used to indicate values and tolerance, with IEC 62 colours being used. A fifth yellow band denotes constant voltage fusibility. Solvent Resistance The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. Flammability The resistors will not burn or emit incandescent particles under any condition of applied temperature or power overload. Dimensions (mm) & Weight (g) Type L D f d PCB Min. Wt. max max min nom mounting bend nom centres radius Physical Data LD f d2.5 Issue E · 01.07
© 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 D · 03.06 Welwyn Components 162 Test Method (for graph 3 and 4) The resistor is subject to 10,000 pulses as shown in figure (1). Maximum resistance change due to test will not exceed 1%. Maximum pulse voltages are detailed in graph 3 above. For any combination of power and pulse length (ti). tp is determined by the need to ensure that the average power does not exceed the rated power. tp = Applied Pulse Power Rated Power x ti 10000010000100010010 100 1000 10000 1.2/50μS Pulse Withstand Value (OHMS) Test Voltage (V) WFF 1/4 WFF 1/2 WFF 1 Graph 1 10000010000100010010 100 1000 10000 10/700μS Pulse Withstand Value (OHMS) Test Voltage (V) WFF 1/4 WFF 1/2 WFF 1 Graph 2 100 1000 10000 Maximum peak pulse voltage as a function of pulse duration (ti) WFF 1/4 WFF 1/2 WFF 1 ti (s) Peak Voltage (V) Graph 3 100 Maximum peak pulse power as a function of pulse duration (ti) WFF 1/4 WFF 1/2 WFF 1 ti (s) Peak Power (W) Graph 4 Above tests carried out in accordance with IEC 115.1. Change of value after test ±1% Voltage (V) Time (secs) tp ti Figure 1 Pulse Handling Graphs Maximum Load: 1000 hrs at 70˚ C 3%R Shelf life: 12 months at room temperature 2%R Derating from rated power at 70˚ 551 ta orezC ˚C Temperature rapid change 5.0%R Resistance to solder heat 5.0%R Performance Data Issue E · 01.07
Body Location f 1.4 m Figure 2 Packaging All resistors are supplied tape packed ready for loading onto automatic sequencing and insertion machines. The standard taping method and critical dimensions are shown in figure 2. Lead Formed resistors can also be supplied. Standard options of Lancet, Radial and Goalpost forming are shown in Lead Form Information section. Fusing (Constant voltage) After fusing the final resistance value will be 50 times the initial value. Fast Fusible Metal Film Resistors WFF Series © 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 D · 03.06 Welwyn Components 163 Type WFF 1/4 WFF1/2 WFF1 Large ammo pack 5000 2500 1500 Standard Quantities Per Package *Contact Welwyn for R10 - 1R0 fusing data Issue E · 01.07