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| 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 RoHS COMPLIANT 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 56 10.5 26 1 16.5 5.7 57 34 O 7.2 35.8 2 M4 USEFUL DEPTH: 8 * Tolerance unless stated: 0.2 mm 60 O 4.2 MECHANICAL SPECIFICATIONS 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 % Mechanical Protection Substrate O 21 ELECTRICAL SPECIFICATIONS Resistance Range Tolerances Power Rating chassis mounted 250 W 1000 W Temperature Coefficient Standard Limiting Element Voltage Dielectric Strength MIL STD 202 (301), 1 minute, 10 mA Max Insulation Resistance Inductance Capacitance Resistor/ ground 0.24 to 1M E24 series 1 % to 10 % at 50 C continuous at 25 C for 10 seconds 250 ppm/C < 1 150 ppm/C > 1 5 kVRMS L connections 7 kVRMS H connections 12 kVRMS > 106 M < 50 nH < 40 pF < 120 pF ENVIRONMENTAL SPECIFICATIONS Thermal Resistance Temperature Range Climatic Category RTH (j-c) 0.22 C/W - 55 C + 125 C 55/125/56 Document Number: 50007 Revision: 08-Jun-06 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 CONDITIONS NF EN 140 000 CEI 115_1 4 Pr/10 s NF EN 140 000 CEI 68214 Test Na 5 cycles - 55 C + 125 C NF EN 140 000 CEI 115_1 1000 h Pr at 70 C MIL STD 202 Method 103 B and D 56 days R.H. 95 % TYPICAL DRIFTS < (0.25 % + 0.05 ) < (0.25 % + 0.05 ) < (0.5 % + 0.05 ) < (0.5 % + 0.05 ) Rapid Temperature Change Load Life Humidity (steady state) RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR Ohmic Value Standard Tolerance Standard TCR Tolerance On Request <1 5% 250 ppm/C 1 % - 2 % - 10 % >1 5% 150 ppm/C 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: T: RTH: RTH: expressed in W difference between maximum working temperature and room temperature. (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). (c-a): thermal resistance value measured between outer side of the resistor and room temperature. It is the thermal resistance of 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: 08-Jun-06 RPS 250 Power Resistor for Mounting onto a Heatsink Thick Film Technology 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 seconds Accidental overload: The values indicated on the graph below are applicable to resistors in air or mounted onto a heatsink. Vishay Sfernice ENERGY CURVE 10 000 1000 ENERGY IN JOULES 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 80 % RATED POWER 60 40 20 Packaging Box of 15 units 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 ORDERING INFORMATION RPS MODEL 250 STYLE DL CONNECTIONS Optional H: dielectric strength 12 kV L: dielectric strength 7 kV 250U 1% ZA3 CUSTOM DESIGN Options on request special TCR, shape, etc. B015 PACKAGING e LEAD (Pb)-FREE RESISTANCE VALUE TOLERANCE Optional 1% 2% 5% 10 % SAP PART NUMBERING GUIDELINES RPS MODEL 0250 STYLE DL CONNECTIONS 2500 OHMIC VALUE F TOLERANCE B PACKAGING ZA3 DESIGN Document Number: 50007 Revision: 08-Jun-06 For technical questions, contact: sfer@vishay.com www.vishay.com 33 Legal Disclaimer Notice Vishay Notice Specifications of the products displayed herein are subject to change without notice. Vishay Intertechnology, Inc., or anyone on its behalf, assumes no responsibility or liability for any errors or inaccuracies. Information contained herein is intended to provide a product description only. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Vishay's terms and conditions of sale for such products, Vishay assumes no liability whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of Vishay products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right. The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications. Customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Vishay for any damages resulting from such improper use or sale. Document Number: 91000 Revision: 08-Apr-05 www.vishay.com 1 |
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