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 WDBR1/2 Resistance range ohms WDBR1 12, 15, 20, 22, 25, 47, 50, 100 WDBR2 WDBR3 WDBR5 WDBR7 12, 15, 20, 22, 25, 47, 50, 100, 150 Resistance tolerance % 1 kW 0.5 1.5 2.0 3.5 5.0 7.0 W 160 180 200 260 270 280 W 300 700 780 900 1000 1490 <4 <5 <6 Pulse power rating Power rating on heatsink 2 Power rating on fan-cooled heatsink 3 TCR 10 ppm/°C Maximum element temperature Ambient temperature range (heatsink) Dielectric withstand 4 +500 to +600 °C 365 °C -55 to +200 V (dc/ac peak) Inductance (typical) 2500 μH <3 Notes: 1. For details of pulse condition see Fig. 1 in Performance Data. 2. Mounted on a 0.53°C/W heatsink with no forced air cooling, air temperature 25°C. 3. Mounted on a 0.53°C/W heatsink with 5m/s forced air cooling, air temperature 25°C. 4. Based on 100% production test, duration 2s minimum Physical Data Dimensions in mm, weight without terminations in g D 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 WDBR5 122 70 14.0 23.8 7.4 60.7 WDBR7 152.4 101.6 0.9 5.3 1.5 15.0 51.3 9.2 181.8 c b W L Substrate thickness = t Fixing hole is located centrally except on WDBR1/2 where the dimension from the edge by the terminations to the mounting hole centre is 16.68mm 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 solder and optional terminals or leads are soldered on. General Note TT electronics reserves the right to make changes in product specification without notice or liability. All information is subject to TT electronics’ own data and is considered accurate at time of going to print. www.bitechnologies.com www.irctt.com www.welwyn-tt.com © TT electronics plc 02.13 Ultra Low Profile Power Resistors WDBR Series Terminations The following termination options are available Code Option Nominal Dimensions 9mm Solder pad only 1 I Flying leads UL3134/5 40A, 600V L 9mm 250mm 3mm 6mm Push-on connectors (WDBR1,2,3,5&7) T 0.8mm 11mm 8mm 8.5mm Notes: 1. Two options exist for solder type. The standard is SnAg (96SC) and the second is high temperature HMP alloy. Thermal Performance Maximum Pulsed load at full pulse power rating 50,000 cycles (see Fig 1) Mounted on a 0.53°C/W heatsink with 5m/s forced air cooling, air temperature 25°C. 5 ΔR% Derating at heatsink temperatures >160°C See Fig. 2 Fig. 1: Duty Cycle Waveform P pk 8s 2s % of Rated Power 1ms 1ms Fig. 2: Temperature Derating 120 100 80 60 40 20 0 0 50 100 150 200 250 Heatsink Temperature (°C) General Note TT electronics reserves the right to make changes in product specification without notice or liability. All information is subject to TT electronics’ own data and is considered accurate at time of going to print. www.bitechnologies.com www.irctt.com www.welwyn-tt.com © TT electronics plc 02.13 Ultra Low Profile Power Resistors WDBR Series 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 an appropriate bolt as listed in the table below. This should be tightened so as to bring the whole area of the steel substrate into intimate contact with the heatsink. The unmounted part is slightly bowed so that the centre is above the edges. Inadequate tightening will leave the centre out of contact with the heatsink, whilst over tightening can cause the edges to rise. The tightening torque required will depend on the fixings and heatsink used, but typical figures are given for guidance. WDBR resistors will fail safe (open circuit) under overload fault conditions and still maintain a 1kV dielectric withstand. Bolt Size Typical Tightening Torque (Nm) WDBR1/2 M2 0.6 WDBR1 M3 2 WDBR2 WDBR3 M5 M5 2.5 2.5 WDBR5 M5 3.5 WDBR7 M5 4 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 Single Overload Energy Capacity Maximum Single Overload Power 100 10 WDBR7 WDBR5 WDBR3 WDBR2 WDBR1 WDBR1/2 1 0.1 0.01 0.1 1 10 100 W 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) Duration of Overload (s) Maximum peak current (A) Value (ohms) 12 15 20 22 25 47 50 100 WDBR1/2 15.2 15.2 7.6 7.6 7.6 7.6 7.6 7.6 WDBR1 21.6 21.6 21.6 8.3 8.3 8.3 8.3 8.3 150 8.3 WDBR2 20.3 20.3 7.6 7.6 7.6 7.6 7.6 7.6 7.6 WDBR3 25.4 25.4 25.4 25.4 11.4 11.4 11.4 11.4 11.4 WDBR5 25.4 25.4 25.4 25.4 25.4 10.2 10.2 10.2 10.2 WDBR7 44.5 44.5 44.5 44.5 44.5 20.3 20.3 20.3 20.3 General Note TT electronics reserves the right to make changes in product specification without notice or liability. All information is subject to TT electronics’ own data and is considered accurate at time of going to print. www.bitechnologies.com www.irctt.com www.welwyn-tt.com © TT electronics plc 02.13 Ultra Low Profile Power Resistors WDBR Series Ordering Procedure Example: WDBR2 at 100 ohms and 10% tolerance with standard solder, flying leads and packed in a box of 84 pieces: WDBR2–100RKLW Type Solder Option 96SC Standard HT HMP High temperature Value (use IEC62 code) Tolerance (use IEC62 code) K 10% Termination I L T Solder pad only Flying leads Push-on connectors Packing W WDBR1/2I 180/box WDBR1/2T 64/box WDBR1/2L, WDBR1L, WDBR2L, WDBR3I, WDBR3T, WDBR5I, WDBR5T WDBR1I, WDBR2I WDBR1T, WDBR2T WDBR3L, WDBR5L, WDBR7 all terminations Bulk 40/box Standard 100/box 80/box 20/box General Note TT electronics reserves the right to make changes in product specification without notice or liability. All information is subject to TT electronics’ own data and is considered accurate at time of going to print. www.bitechnologies.com www.irctt.com www.welwyn-tt.com © TT electronics plc 02.13