RPS 250 Vishay Sfernice Power Resistor for Mounting onto a Heatsink Thick Film Technology FEATURES * High power rating: 250 W * High overload capability up to 4 times nominal power (see energy curve) * Easy mounting * Low thermal radiation of the case Developed for specific applications such as railroad electrical traction, this series can bear short overloads as high as fifteen times the nominal power. Designed to be mounted onto a heatsink, these power resistors exhibit remarkable characteristics. DIMENSIONS in millimeters RPS 250D 73 5.7 10.5 56 26 1 57 34 16.5 O 21 O 4.2 35.8 60 O 7.2 2 M4 USEFUL DEPTH: 8 * Tolerance unless stated: 0.2 mm MECHANICAL SPECIFICATIONS Mechanical Protection Substrate Insulated case Alumina onto aluminum base Resistive Element Cermet End Connections Screws M4, (M5 on request) Tightening Torque on connections 2 Nm Weight 170 g 10 % ENVIRONMENTAL SPECIFICATIONS ELECTRICAL SPECIFICATIONS Resistance Range Tolerances Document Number: 50007 Revision: 24-Nov-08 RTH (j-c) 0.22 C/W - 55 C + 125 C 55/125/56 1 % to 10 % Power Rating chassis mounted 250 W 1000 W at 50 C continuous at 25 C for 10 s Temperature Coefficient Standard 250 ppm/C < 1 150 ppm/C > 1 Limiting Element Voltage UL 5 kVRMS Dielectric Strength L connections 7 kVRMS MIL STD 202 (301), 1 min, 10 mA max. H connections 12 kVRMS Insulation Resistance Thermal Resistance Temperature Range Climatic Category 0.24 to 1M E24 series > 106 M Inductance < 50 nH Capacitance Resistor/ ground < 40 pF < 120 pF For technical questions, contact: sfer@vishay.com www.vishay.com 31 RPS 250 Vishay Sfernice Power Resistors for Mounting onto a Heatsink Thick Film Technology PERFORMANCE TESTS Momentary Overload Rapid Temperature Change Load Life Humidity (steady state) CONDITIONS REQUIREMENTS NF EN 140 000 CEI 115_1 4 Pr/10 s/UL = 5000 V < (0.25 % + 0.05 ) NF EN 140 000 CEI 68214 Test Na 5 cycles - 55 C + 125 C < (0.25 % + 0.05 ) NF EN 140 000 CEI 115_1 1000 h Pr at 70 C < (0.5 % + 0.05 ) MIL STD 202 Method 103 B and D 56 days R.H. 95 % < (0.5 % + 0.05 ) RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR Ohmic Value <1 >1 Standard Tolerance 5% 5% Standard TCR (- 55 C to + 125 C) Tolerance On Request 250 ppm/C 150 ppm/C 1 % - 2 % - 10 % CHOICE OF THE HEATSINK The user must choose the heatsink according to the working conditions of the component (power, room temperature). Maximum working temperature must not exceed 125 C. The dissipated power is simply calculated by the following ratio: (1) T P = --------------------------------------------------------------------[RTH (j - c) + RTH (c - a)] P: Expressed in W T: Difference between maximum working temperature and room temperature RTH: (j-c): Thermal resistance value measured between resistive layer and outer side of the resistor. It is the thermal resistance of the component: (see specifications environmental paragraph). RTH: (c-a): Thermal resistance value measured between outer side of the resistor and room temperature. It is the thermal resistance of the heatsink, depending on the heatsink itself (type, shape) and the quality of the fastening device. Example: RTH: (c-a) for RPS 250 power dissipation 180 W at + 50 C room temperature. T 125 C - 50 C 75 C T 75 RTH (j-c) + RTH (c-a) = ------- = ---------- = 0.42 C/W P 180 RTH (j-c) = 0.22 C/W RTH (c-a) 0.42 C/W - 0.22 C/W 0.20 C/W RECOMMENDATIONS FOR MOUNTING ONTO A HEATSINK Surfaces in contact must be carefully cleaned. The heatsink must have an acceptable flatness: from 0.05 mm to 0.1 mm/100 mm. Roughness of the heatsink must be around 6.3 m. In order to improve thermal conductivity, surfaces in contact should be coated with a silicone grease (type SI 340 from Rhone-Poulenc or Dow 340 from Dow Corning). The fastening of the resistor to the heatsink is under pressure control of two screws (tightening torque 3 Nm). In order to improve the dissipation, either forced-air cooling or liquid cooling may be used. Do not forget to respect an insulation value between two resistors (dielectric strength in dry air 1 kV/mm). In any case the hot spot temperature, measured locally on the case must not exceed 125 C. Test should be performed by the user. www.vishay.com 32 For technical questions, contact: sfer@vishay.com Document Number: 50007 Revision: 24-Nov-08 RPS 250 Power Resistor for Mounting onto a Heatsink Thick Film Technology Vishay Sfernice OVERLOADS In any case the applied voltage must be lower than 2.5 Un. U maxi < 2.5 Un < 12 500 V. Short time overload: 4 Pn/10 s Accidental overload: The values indicated on the graph below are applicable to resistors in air or mounted onto a heatsink. ENERGY CURVE 10 000 ENERGY IN JOULES 1000 100 10 1 0.13 1 s 10 s 100 s 1 ms 10 ms 100 ms 1s OVERLOAD DURATION IN SECONDS POWER RATING CHART The temperature of the heatsink should be maintained in the limit specified. To improve the thermal conductivity, surfaces in contact should be coated with a silicone grease. 100 % RATED POWER 80 60 40 20 0 0 20 40 60 80 100 120 140 HEATSINK TEMPERATURE IN DEGREES CELSIUS MARKING Series, style, ohmic value (in ), tolerance in %, manufacturing date, VISHAY trademark PACKAGING Packaging box of 15 units Document Number: 50007 Revision: 24-Nov-08 For technical questions, contact: sfer@vishay.com www.vishay.com 33 RPS 250 Power Resistors for Mounting onto a Heatsink Thick Film Technology Vishay Sfernice GLOBAL PART NUMBER INFORMATION R P GLOBAL MODEL RPS250 S 0 2 5 0 D L 2 R 2 0 J B Z A 3 STYLE DIELECTRIC OHMIC VALUE TOLERANCE PACKAGING TYPE D = Diagonal connections A = Straight connections H = Dielectric strength 12 kV L = Dielectric strength 7 kV The first three digits are significant figures and the last digit specifies the number of zeros to follow. R designates decimal point. 2R20 = 2.20 48R7 = 48.7 47R0 = 47 1001 = 1 k 4R70 = 4.7 R240 = 0.24 F=1% G=2% J=5% K = 10 % B = Box, 15 pcs N = Box, 15 pcs N/A (1 to 14 pcs by box) Standard RPS250A = Blank Standard RPS250D = ZA3 Special = Blank (for RPS250D) or as applicable = ZAx www.vishay.com 34 For technical questions, contact: sfer@vishay.com Document Number: 50007 Revision: 24-Nov-08 Legal Disclaimer Notice Vishay Disclaimer All product specifications and data are subject to change without notice. Vishay Intertechnology, Inc., its affiliates, agents, and employees, and all persons acting on its or their behalf (collectively, "Vishay"), disclaim any and all liability for any errors, inaccuracies or incompleteness contained herein or in any other disclosure relating to any product. Vishay disclaims any and all liability arising out of the use or application of any product described herein or of any information provided herein to the maximum extent permitted by law. The product specifications do not expand or otherwise modify Vishay's terms and conditions of purchase, including but not limited to the warranty expressed therein, which apply to these products. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document or by any conduct of Vishay. The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications unless otherwise expressly indicated. Customers using or selling Vishay products not expressly indicated for use in such applications do so entirely at their own risk and agree to fully indemnify Vishay for any damages arising or resulting from such use or sale. Please contact authorized Vishay personnel to obtain written terms and conditions regarding products designed for such applications. Product names and markings noted herein may be trademarks of their respective owners. Document Number: 91000 Revision: 18-Jul-08 www.vishay.com 1