Ultra Low Profile Power Resistors WDBR Series • • • • • • • • Ultra low profile thick-film on steel 500W to 7kW peak power Single fixing heatsink mountable Ideal for dynamic braking, inrush limit and snubber circuits Choice of flying lead, push-on or solder terminations Low inductance design High isolation, even after failsafe overload fusing RoHS compliant, non-flammable construction Electrical Data Resistance range ohms Resistance tolerance % Pulse power rating 1 kW Power rating on heatsink 2 W Power rating on fan-cooled heatsink 3 W TCR ppm/°C Maximum element temperature °C Dielectric withstand V (dc/ac peak) Inductance (typical) μH Notes: 1. 2. 3. 4. WDBR1/2 22, 47, 100 WDBR1 0.5 160 300 1.5 180 700 <3 WDBR2 WDBR3 12, 22, 47, 100, 150 10 2.0 3.5 200 260 780 900 +500 to +600 365 2500 <4 WDBR5 WDBR7 47, 100, 150 5.0 270 1000 7.0 280 4 1490 4 <5 <6 D c For details of pulse condition see Fig. 1 in Performance Data. Mounted on a 0.53°C/W heatsink with no forced air cooling, air temperature 25°C. Mounted on a 0.53°C/W heatsink with 5m/s forced air cooling, air temperature 25°C. Limited by the solder type; the rating can be improved for non-standard parts by using HMP solder. Physical Data Dimensions in mm, weight without terminations in g a L ±0.1 W ±0.1 t ±0.1 ØD nom a nom b nom c nom Wt. nom WDBR1/2 31.9 28.1 2.2 7.5 3.1 4.3 6.5 WDBR1 49.3 35.9 3.2 3.2 11.2 6.2 12.6 WDBR2 61 40.6 4.7 13.0 5.8 17.1 WDBR3 101.6 70 13.5 22.0 10.2 50.8 14.0 23.8 7.4 60.7 15.0 51.3 9.2 181.8 0.9 b W L 5.3 WDBR5 122 70 WDBR7 152.4 101.6 1.5 Substrate thickness = t Fixing hole is located centrally Construction A high integrity dielectric layer is applied to a machined stainless steel substrate. Thick-film conductor and resistor patterns are printed and fired, then protected with a high temperature overglaze. The termination pads are tinned with Pb-free solder and optional terminals or leads are soldered on. 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 test data and is considered accurate at time of print. Welwyn Components Limited Welwyn Electronics Park, Bedlington, Northumberland, NE22 7AA, England. Tel: 01670 822181 Fax: 01670 829465 Web: www.welwyn-tt.com Ultra Low Profile Power Resistors WDBR Series Terminations The following termination options are available Option Code Nominal Dimensions 9mm Solder pad only I 9mm SnAg (96S) 250mm Flying leads 3mm L UL3134 40A, 600V 0.8mm 6mm Push-on connectors 11mm T (WDBR1,2,3,5&7) 8.5mm 8mm Performance Data Maximum Pulsed load at full pulse power rating 50,000 cycles (see Fig 1) ΔR% Mounted on a 0.53°C/W heatsink with 5m/s forced air cooling, air temperature 25°C. 5 Derating at heatsink temperatures >160°C See Fig. 2 Fig. 2: Temperature Derating Fig. 1: Duty Cycle Waveform 1ms P pk 8s 1ms 2s % of Rated Power 120 100 80 60 40 20 0 0 50 100 150 200 250 Heatsink Temperature (°C) Application Notes A heatsink with thermal resistance ≤0.53°C/W will enable the component to operate at its continuous power rating. Thermal grease (e.g. Dow Corning DC340) should be used and the heatsink should have a surface finish of <6.3μm with flatness of <0.05mm. The resistor should be mounted using a screw head bolt of size M5 for WDBR2, 3, 5 & 7, M3 for WDBR1 and M2 for WDBR1/2. This should be torqued to 2.5Nm ±10%. WDBR resistors will fail safe (open circuit) under overload fault conditions and still maintain a 1kV dielectric withstand. 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 test data and is considered accurate at time of print. Welwyn Components Limited Welwyn Electronics Park, Bedlington, Northumberland, NE22 7AA, England. Tel: 01670 822181 Fax: 01670 829465 Web: www.welwyn-tt.com Ultra Low Profile Power Resistors WDBR Series WDBR resistors may be customised in various ways including: • Alternative shapes and dimensions up to 406mm x 406mm • Integration of temperature measurement elements • Alternative ohmic values, tolerance & TCR • Increased dielectric withstand voltage • Custom braking resistors with UL approval For a full Applications Note for dynamic braking see http://www.welwyn-tt.com/pdf/application_notes/WDBR.pdf Overload conditions Maximum Single Overload Power Single Overload Energy Capacity 100 10 WDBR7 WDBR5 WDBR3 WDBR2 WDBR1 WDBR1/2 1 0.1 0.01 0.1 1 10 Duration of Overload (s) 100 Energy (kJ) Power (kW) 100 WDBR5 WDBR3 WDBR2 WDBR1 WDBR7 10 WDBR1/2 1 0.1 0.01 0.01 0.1 1 10 100 Duration of Overload (s) Ordering Procedure Example: WDBR2 at 100 ohms and 10% tolerance with flying leads and packed in a box of 84 pieces: WDBR2–100RKLW Type Value (use IEC62 code) Tolerance (use IEC62 code) K 10% Termination I L T Solder pad only Flying leads Push-on connectors Packing W Bulk Pack WDBR1/2,1&2 WDBR3 WDBR5&7 84/box 70/box 60/box Standard 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 test data and is considered accurate at time of print. 10/08 Welwyn Components Limited Welwyn Electronics Park, Bedlington, Northumberland, NE22 7AA, England. Tel: 01670 822181 Fax: 01670 829465 Web: www.welwyn-tt.com