Compact Flameproof Power Wirewound Resistors Welwyn Components WP-S Series • • • • • Small size for power rating Enhanced pulse handling capability Flameproof protection SMD Z-form available RoHS compliant with Pb-free terminations Electrical Data WP1S WP2S WP25S WP3S WP4S WP5S WP7S Power rating at 25°C watts 1 2 2.5 3 4 5 7 5s overload rating at 25ºC watts 5 10 12.5 15 20 25 35 Short pulse performance See Pulse Performance graphs Resistance range ohms R068 to 430R R05 to 900R Limiting element voltage volts 50 50 TCR R05 to 900R R01 to 2K2 75 ppm/°C Isolation Voltage Resistance Tolerance 250 % <20R: 5 350 150 150 500 ≥20R: 1, 2, 5 Standard Values R015 to 6K8 R15 to 10K 100 ≥1R: 200 <1R: 350 volts R01 to 10K 100 <R10: 5 ≥R10: 1, 2, 5 700 <20R: 5 ≥20R: 1, 2, 5 E24 preferred Thermal Impedance °C/watt Ambient temperature range 140 110 90 82 °C 62 54 35 -55 to +155 Physical Data Dimensions (mm) & Weight (g) Type L max D max f min d nom PCB mount centres Min bend radius Wt. nom WP1S 6.2 2.8 21.20 0.6 10.20 0.6 0.22 WP2S 9.0 3.6 19.80 12.70 0.50 WP25S 12.5 4.5 17.80 18.40 0.50 WP3S 14.5 5.2 24.55 20.30 0.8 18.90 D 1.10 1.2 WP4S 13 5.6 22.75 1.00 WP5S 16.5 7.0 23.55 22.86 1.75 WP7S 25.0 8.8 28.30 31.40 4.40 d L f Construction A high purity ceramic substrate is assembled with interference fit end caps to which are welded the terminations. The resistive element is wound on the substrate and welded to the caps. Flameproof silicone cement coating is applied prior to marking with indelible ink. The components are then leadformed if required and packed. 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 Issue E · 07.06 Compact Flameproof Power Wirewound Resistors Welwyn Components WP-S 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 Marking WP1S, WP2S, WP25S and WP3S resistors R10 and above are marked with four or five colour bands in conformance with IEC62. Values below R10 are marked with three bands (two digits indicating value in milliohms, and tolerance); there is no multiplier band. WP4S, WP5S and WP7S resistors are legend marked with type reference, resistance value and tolerance. 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 Load at rated power: 1000hrs @ 25°C Dry heat: 1000hrs @ 200°C Short term overload (5 x Pr for 5s) Maximum Typical Change ∆R% ∆R% ∆R% 5 +0.001Ω 3 5 +0.001Ω 3 5 +0.001Ω 1 ∆R% 5 +0.001Ω Derating from rated power @25°C Zero at 280°C Climatic 2 Climatic category 55/200/56 ∆R% ∆R% ∆R% TRC & Vibration Robustness & solder heat Long term damp heat (56 days) 5 +0.001Ω 1 5 +0.001Ω 1 5 +0.001Ω 1 Pulse Performance The pulse energy capacity limits in the graph below relate to pulses below 100ms duration, low mean power dissipation and at 25ºC. WP-S Short Pulse Energy Capacity Energy (joules) 100 10 WP7S WP5S WP4S 1 WP25S WP3S WP2S WP1S 0.1 0.1 1 10 100 1000 10000 Value (ohms) © 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 Issue E · 07.06 Compact Flameproof Power Wirewound Resistors Welwyn Components WP-S Series 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 at the center of the body can be calculated using the thermal impedance figures given under Electrical Data. 3. WP-S resistors can also be supplied with radial, goalpost or lancet pre-formed leads. WP2S, WP3S, WP4S and WP5S are also available in an SMD format with Z formed leads and packed in blister tape. Consult factory for details. Radial Goalpost Lancet Z-form Packaging The standard packaging for WP-S 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 boxes or onto reels; see Ordering Procedure for details. Alternative packaging is available by request. Pre-formed resistors are supplied loose packed in plastic bags or boxes. Figure 1 Dimensions (mm) b c WP1S 52 5 WP2S 52 5 WP25S 52 5 WP3S 67 10 WP4S 63 10 WP5S 63 10 WP7S 85 10 C f1 b f2 6 6 Body location f1 - f2 < 1.4mm © 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 Issue E · 07.06 Compact Flameproof Power Wirewound Resistors Welwyn Components WP-S Series Ordering Procedure Example: WP2S at 680 ohms and 5% tolerance in ammo pack box of 2500 pieces WP2S Type – 680R J A25 Value (use IEC 62 code) Tolerance (use IEC 62 code) F 1% G 2% J 5% Packing A5 WP1S 5000/box A25 WP2S 2500/box WP25S 1500/box A1 WP3S 1000/box A1 WP4S 1000/box A15 T075 T07 Ammo Tape Tape WP5S 700/reel WP7S 700/reel 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 Issue E · 07.06