RPS 250 www.vishay.com 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 * Material categorization: for definitions of compliance please see www.vishay.com/doc?99912 DESIGN SUPPORT TOOLS click logo to get started Models Available 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 73 56 28 1 57 34 16.2 18.7 57 O 7.2 38.1 O 4.2 O 21 O 4.2 60 35.8 O 7.2 O 21 60 6 10.5 26 1 73 56 RPS 250A ZA3 6 10.5 RPS 250D ZA3 2 x M4 USEFUL DEPTH: 6 2 x M4 USEFUL DEPTH: 6 Note * Tolerance unless stated: 0.2 mm STANDARD ELECTRICAL SPECIFICATIONS MODEL SIZE RPS 250 Note (1) E24 series 250 RESISTANCE RANGE 0.24 to 1M (1) RATED POWER P25 C W 250 MECHANICAL SPECIFICATIONS Mechanical Protection Resistive Element Substrate End Connections Tightening Torque Connections Weight Insulated case and resin for potting UL 94 V-0 Cermet Alumina onto aluminum base Screws M4 (M5 on request) 2 Nm 170 g 10 % ENVIRONMENTAL SPECIFICATIONS Thermal Resistance Temperature Range Climatic Category Revision: 01-Dec-17 Rth (j - c) 0.22 C/W -55 C to 125 C 55 / 125 / 56 LIMITING ELEMENT VOLTAGE UL V 5000 TEMPERATURE COEFFICIENT ppm/C 150 TOLERANCE % 1, 2, 5, 10 TECHNICAL SPECIFICATIONS Power Rating Chassis Mounted Temperature Coefficient Standard 250 W at 50 C continuous 1000 W at 25 C for 10 s 250 ppm/C < 1 150 ppm/C > 1 Dielectric Strength MIL STD 202 (301), min, 10 mA max. L connections 7 kVRMS H connections 12 kVRMS Insulation Resistance 106 M Inductance 50 nH Capacitance Resistor/ Ground < 40 pF < 120 pF Document Number: 50007 1 For technical questions, contact: sferfixedresistors@vishay.com THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 RPS 250 www.vishay.com Vishay Sfernice PERFORMANCE TESTS CONDITIONS REQUIREMENTS NF EN 140000 CEI 115_1 4 Pr / 10 s / UL = 5000 V < (0.25 % + 0.05 ) NF EN 140000 CEI 68214 Test Na 5 cycles -55 C +125 C < (0.25 % + 0.05 ) NF EN 140000 CEI 115_1 1000 h Pr at 70 C < (0.5 % + 0.05 ) MIL STD 202 Method 103 B and D 56 days RH 95 % < (0.5 % + 0.05 ) Momentary Overload Rapid Temperature Change Load Life Humidity (Steady State) RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR Ohmic Value <1 >1 Standard Tolerance 5% 5% Standard TCR (-55 C to +125 C) 250 ppm/C Tolerance on Request 150 ppm/C 1 %/ 2 %/ 10 % 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 (alumina, heatsink) 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 four screws (not supplied). RPS 250 Tightening Torque on Heatsink 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. 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: T P = ---------------------------------------------------------------------------------------------------- R th (j - c) + R th (c - h) + R th (h - a) P: T: Rth (j - c): Expressed in W Difference between maximum working temperature and room temperature Thermal resistance value measured between resistive layer and outer side of the resistor. It is the thermal resistance of the component: (see Environmental Specifications). Rth (c - h): Thermal resistance value measured between outer side of the resistor and upper side of the heatsink. This is the thermal resistance of the interface (grease, thermal pad), and the quality of the fastening device. Rth (h - a): Thermal resistance of the heatsink. Example: Rth (c - a): for RPS 250 power dissipation 180 W at +50 C room temperature. T 125 C - 50 C 75 C 75 T Rth (j - c) + Rth (c - h) + Rth (h - a) = ------- = -------- = 0.42 C/W 180 P Rth (j - c) = 0.22 C/W Rth (c - h) + Rth (h - a) 0.42 C/W - 0.22 C/W 0.20 C/W Revision: 01-Dec-17 Document Number: 50007 2 For technical questions, contact: sferfixedresistors@vishay.com THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 RPS 250 www.vishay.com Vishay Sfernice OVERLOADS POWER RATING In any case the applied voltage must be lower than 2.5 Un. Umax. < 2.5 Un < 12 500 V. Short time overload: 4 Pr/10 s Accidental overload: The values indicated on the graph below are applicable to resistors in air or mounted onto a heatsink. 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 IN % ENERGY CURVE ENERGY IN JOULES 10 000 1000 100 10 80 60 40 20 1 0 0 20 0.1 10-7 10-6 10-5 10-4 10-3 10-2 10-1 40 60 80 100 120 140 HEATSINK TEMPERATURE IN C 100 OVERLOAD DURATION IN s POWER CURVE PACKAGING 10 000 000 Box of 15 units POWER IN W 1 000 000 MARKING Series, style, ohmic value (in ), tolerance in %, manufacturing date, Vishay Sfernice trademark 100 000 10 000 1000 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 OVERLOAD DURATION IN s GLOBAL PART NUMBER INFORMATION R GLOBAL MODEL RPS250 P 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) Square sole = blank Cropped sole = ZA3 As applicable = ZAx Revision: 01-Dec-17 Document Number: 50007 3 For technical questions, contact: sferfixedresistors@vishay.com THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 Legal Disclaimer Notice www.vishay.com Vishay Disclaimer ALL PRODUCT, PRODUCT SPECIFICATIONS AND DATA ARE SUBJECT TO CHANGE WITHOUT NOTICE TO IMPROVE RELIABILITY, FUNCTION OR DESIGN OR OTHERWISE. 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