UL Recognised Wirewound Resistors Welwyn Components ULW Series · UL1412 recognised fusible resistor * · Failsafe mains fusing at 120 / 240Vrms · Inrush and surge withstanding · UL94-V0 flameproof coating · SMD leadform option available · RoHS compliant * UL file number E234469. Electrical Data ULW2 ULW3 ULW4 Power rating at 25°C watts 2 3 4 5 second overload rating at 25ºC watts 10 15 20 ohms 22 to 100 Inrush / surge performance See Pulse Performance graphs Resistance range TCR 10 to 100 ppm/°C Isolation voltage ±200 volts Resistance tolerance 250 350 % UL recognised standard values ohms Thermal impedance 500 5 22, 33, 47, 68, 100 10, 22, 27, 33, 47, 68, 100 10 110 82 62 °C/watt Ambient temperature range 10 °C -55 to +155 Note - no limiting element voltage applies; maximum continuous voltage is √(P.R) Physical Data Dimensions (mm) and weight (g) Type L Max D Max f min ULW2 9.0 3.6 19.8 ULW3 14.5 5.2 24.6 ULW4 13 5.6 22.8 d nom PCB mount centres Min bend radius 12.7 0.8 20.3 18.9 Min bend radius 0.5 1.2 1.1 d D L f 1.0 Construction A high purity ceramic rod is assembled with interference fit end caps to which are welded the terminations. The surge withstanding resistive element is wound on the rod and welded to the caps. Flameproof fusible cement coating is applied prior to marking with indelible ink. The components are then leadformed if required and packed. Marking ULW2 & ULW3 resistors are marked with five colour bands. The first four indicate value and tolerance in conformance with IEC62. The fifth yellow band denotes defined fusibility. ULW4 resistors are legend marked with type, value and tolerance. 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 © 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 03. 09 UL Recognised Wirewound Resistors Welwyn Components ULW Series Terminations Material: Strength: Solderability: Hot tin dipped copper wire The terminations meet the requirements of IEC 68.2.21 The terminations meet the requirements of IEC 115-1 Clause 4.17.3.2 Solvent Resistance The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. Flammability The resistor coating will not burn or emit incandescent particles under any condition of applied temperature or power overload. Performance Data Maximum Typical 5 3 Load at rated power (1000 hours @ 25°C) ΔR% Short term overload (5 x Pr for 5 seconds) ΔR% 5 1 Pulse (see Pulse Performance graphs) ΔR% 5 2 Climatic ΔR% 5 2 Long term damp heat (56 days) ΔR% 5 1 Temperature rapid change ΔR% 5 1 Dry heat (1000 hours @ 200°C) ΔR% 5 3 Climatic category 55/200/56 Vibration ΔR% 5 1 Robustness & solder heat ΔR% 5 1 Thermal Performance Derating Curve Body Temperature Rise Temperature Rise (°C) Proportion of Rated Power (%) 250 ULW3 100 80 60 40 20 0 ULW2 200 ULW4 150 100 50 0 0 50 100 150 200 250 300 0 1 Am bient Tem perature (°C) 2 3 4 Pow er (W) © 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 03. 09 UL Recognised Wirewound Resistors Welwyn Components ULW Series Pulse Performance Pulse Energy Limit (single or low repetition rate, 1.2/50µs Peak Voltage Limit R<5%) 8 ULW3 7 5 6 5 Peak Voltage (kV) Pulse Energy (J) (10 pulses at 10s intervals, R<5%) Note the voltage show n is the nett voltage across the resistor. The generator open circuit voltage w ill be higher due to the generator's internal impedance. 4 3 ULW2 2 1 ULW3 4 3 ULW2 2 1 0 0 0 10 20 30 40 50 60 70 80 90 0 100 10 20 30 40 50 60 70 80 90 100 Value (ohm s) Value (ohms) ULW4-10RJ has an energy limit of 4.3J and a 1.2/50 s peak voltage limit of 1.1kV. Fusing Performance Maximum Fusing Time (s) ULW2 Fusing Characteristic 60 50 40 30 20 10 0 30 35 40 45 50 55 60 Initial Power (W) Maximum Fusing Time (s) ULW3 & ULW4 Fusing Characteristic 60 50 40 30 20 10 0 50 60 70 80 90 100 110 120 Initial Power (W) Notes: 1. Typical fusing times are around 1/3 of the maximum figures. 2. After fusing the resistance value is >100 times the initial nominal value. 3. Suitable for fusing at voltages up to 264Vrms. © 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 03. 09 UL Recognised Wirewound Resistors Welwyn Components ULW Series Application Notes Application Notes 1. If the resistors are to dissipate full rated power, it is recommended that the terminations should not be soldered closer than 4mm from the body. 2. Due to operating temperature limits imposed by some PCB materials, derating may be necessary. An estimate of the temperature rise to be expected can be calculated using the thermal impedance figures given under Electrical Data. 3. For the purposes of UL approval, the following points should be observed: 3.1 To protect against fire under all conditions of overload, a positive clearance of at least 13mm should be provided between the body of the resistor and any combustible materials. 3.2 A positive clearance of 13mm should be provided between the resistor body or terminations and uninsulated parts of opposite polarity or uninsulated dead metal parts. 3.3 Limited Short Circuit testing should be performed in the complete appliance. Packaging The standard packaging for ULW is taped. The critical dimensions are shown in Figure 1. The component wires will not protrude beyond the outside edge of the tapes. Taped product is then packed into ammo boxes. Alternative packaging is available by request. Pre-formed resistors are supplied loose packed in plastic bags or boxes. For SMD leadformed option, see the Z-form datasheet. Figure 1 F Dimensions (mm) Type b C ULW2 52 5 ULW3 67 10 C f1 6 ULW4 63 b f2 6 Body location f1 - f2 <1.4mm 10 Ordering Procedure Example: ULW2 at 33 ohms and 5% tolerance in ammo pack box of 2500 pieces ULW2 – 33R J A25 Type Value (use IEC62 code) Tolerance (use IEC62 code) J 5% Packing A25 A1 Ammo ULW2 2500/box ULW3, ULW4 1000/box Standard © 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 03. 09