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Details, datasheet, quote on part number:RPS250
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Datasheet text preview:
RPS 250
Vishay Sfernice
Power Resistor for Mounting onto a Heatsink Thick Film Technology
FEATURES
· High power rating · High overload capability · 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, compact and hermetically sealed, these power resistors exhibit remarkable characteristics.
DIMENSIONS in millimeters
RPS 250D
73 56
10.5 26 ± 1 16.5
5.7
57 34
Ø 7.2 35.8 2 M4 USEFUL DEPTH : 8
· Tolerance unless stated: ± 0.2mm
60
Ø 4.2
MECHANICAL SPECIFICATIONS
Mechanical Protection Substrate Resistive Element End Connections Insulated case Alumina onto aluminum base Cermet Screws M4, (M5 on request) 170g ± 10%
Ø 21
ELECTRICAL SPECIFICATIONS
Resistance Range Tolerances Power Rating chassis mounted 250W 1000W Temperature Coefficient Standard Limiting Element Voltage Dielectric Strength ± 250ppm/°C 1 5kVRMS L connections 7kVRMS H connections 14kVRMS > 106M < 50 nH Resistor /ground < 40pF < 120pF 0.24 to 1M E24 series ± 1% to ± 10% at 50°C continuous at 25°C for 10 seconds
Tightening Torque on connections 2Nm Weight
ENVIRONMENTAL SPECIFICATIONS
Thermal Resistance Temperature Range Climatic Category RTH (j-c) 0.22°C/W - 55°C + 125°C 55/125/56
Insulation Resistance Inductance Capacitance
Document Number: 50007 Revision 20-Mar-02
For technical questions, contact sfer@vishay.com
www.vishay.com 31
RPS 250
Vishay Sfernice
PERFORMANCE
TESTS Momentary Overload Climatic Sequence CONDITIONS 4 Pr/10 s 5 cycles - 55°C + 125°C 1000h Pr at 70°C 56 days R.H. 95% TYPICAL DRIFTS < ± (0.25% ± 0.05) < ± (0.25% ± 0.05)
Power Resistor for Mounting onto a Heatsink Thick Film Technology
Load Life Humidity (steady state)
< ± (0.5% ± 0.05) < ± (0.5% ± 0.05)
RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR
Ohmic Value Standard Tolerance Standard T.C. Tolerance On Request 1 ± 5% ± 150ppm/°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: 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 180W at + 50°C room temperature. T 125°C - 50°C 75°C 75 RTH (j-c) + RTH (c-a) = T = = 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 0.05mm to 0.1mm/100mm. Roughness of the heatsink must be around 6.3µm. In order to improve thermal conductivity, surfaces in contact should be coated with a silicone grease (type SI 340 from Rhône-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 1kV/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 20-Mar-02
RPS 250
Power Resistor for Mounting onto a Heatsink Thick Film Technology
OVERLOADS
In any case the applied voltage must be lower than 2.5Un. U maxi < 2.5Un < 12500V. 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
10000
1000
ENERGY IN JOULES
100
10
1
0.13 1µS 10µS 100µS 1MS 10MS 100MS 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
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 250D STYLE H CONNECTIONS Optional H: dielectric strength 14 kV L: dielectric strength 7 kV 100 RESISTANCE VALUE ± 10% TOLERANCE Optional ± 1% ± 2% ± 5% ± 10% xxx CUSTOM DESIGN Options on request special T.C., shape, etc.
Document Number: 50007 Revision 20-Mar-02
For technical questions, contact sfer@vishay.com
www.vishay.com 33
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