RPH 100 Vishay Sfernice Power Resistor for Mounting onto a Heatsink Thick Film Technology FEATURES High power rating Low thermal radiation of the case Wide ohmic value range Easy mounting High overload capabilities Reduced size and weight This new style has been developed as an extension to RCH range. Through the use of thick film technology, a non-inductive solution for power resistors is available which are rated up to 100 W at + 25 C. The terminations position prevents any risk of an electrical arc to the heatsink. This resistor series can replace and offer advantages to standard wirewound devices. DIMENSIONS in millimeters RPH 100 V Connections 42.4 4 18.6 21.6 16.6 65.5 35 4.2 26 37 46.7 4.2 MECHANICAL SPECIFICATIONS ELECTRICAL SPECIFICATIONS Mechanical Protection Insulated case Resistance Range 0.092 to 1 M E24 series Substrate Alumina on metallic Tolerances 1 % to 10 % base of nickel coated Power Rating: aluminum Continuous 100 W at 25 C Resistive Element Cermet chassis mounted 0.45 C/W End Connections V connections: 10 W at 25 C Screws M4 x 6 Free air Tightening Torque Connections 1 Nm Momentary 400 W at 25 C for 5 s Tightening Torque Heatsink 3 Nm Temperature Coefficient 300 ppm/C < 1 Weight 60 g Standard 150 ppm/C > 1 Limiting Element Voltage U 1900 V L RMS ENVIRONMENTAL SPECIFICATIONS Dielectric Strength MIL STD 202 5 kV 1 min 10 mA max. RMS Thermal Resistance R (j-c) 0.55 C/W TH 6 Insulation Resistance > 10 M Temperature Range - 55 C + 125 C Inductance < 0.1 H Climatic Category 55/125/56 www.vishay.com For technical questions, contact: sfer vishay.com Document Number: 50046 1 Revision: 10-Oct-08RPH 100 Power Resistor for Mounting onto a Heatsink Vishay Sfernice Thick Film Technology PERFORMANCE TESTS CONDITIONS REQUIREMENTS Short Time Overload NF EN 140000 CEI 115 1 < (0.25 % + 0.05 ) 4 P /5 s U < 2 U n S L Rapid Temperature Change NF EN 140000 CEI 68214 Test Na < (0.25 % + 0.05 ) 5 cycles - 55 C + 125 C Load Life (Chassis Mounted 0.45 C/W) NF EN 140000 < (0.5 % + 0.05 ) P at 25 C 1000 h n Humidity (Steady State) MIL STD 202 Method 103 B Test D < (0.5 % + 0.05 ) 56 days 95 % RH RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR Ohmic Value < 1 > 1 Standard Tolerance 5 % 5 % Standard TCR 300 ppm/C 150 ppm/C Tolerance On Request 1 % - 2 % CHOICE OF THE HEATSINK The user must choose 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 ratios: ()1 T P = ------------------------------------------------------------------ R ()jc + R()ca TH TH P: Expressed in W T: Difference between maximum working temperature and room temperature. R : (j-c): thermal resistance value measured between resistive layer and outer side of the resistor. TH It is the thermal resistance of the component: 0.55 C/W. R : (c-a): thermal resistance value measured between outer side of the resistor and room temperature. TH It is the thermal resistance of the heatsink itself (type, shape) and the quality of the fastening device. Example: R : (c-a) for RPH 100 power rating 80 W at ambient temperature + 40 C. TH Thermal resistance R (j-c): 0.55 C/W TH Considering equation (1) we have: T 125 C - 40 C 85 C T 85 R (j-c) + R (c-a) = ------- = ------ = 1.06 C/W TH TH P 80 R (c-a) 1.06 C/W - 0.55 C/W 0.51 C/W TH RECOMMENDATIONS FOR MOUNTING ONTO A HEATSINK Surfaces in contact must be carefully cleaned. The heatsink must have an acceptable fl atness: 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 Rhne-Poulenc or Dow 340 from Dow Corning). The fastening of the resistor to the heatsink is under pressure control of four screws (not supplied). 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). Document Number: 50046 For technical questions, contact: sfer vishay.com www.vishay.com Revision: 10-Oct-08 2