RPS 250
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Revision: 01-Dec-17 1Document Number: 50007
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
Power Resistor for Mounting onto a Heatsink
Thick Film Technology
DESIGN SUPPORT TOOLS
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
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.
Note
• Tolerance unless stated: ± 0.2 mm
Note
(1) E24 series
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Available
Models
DIMENSIONS in millimeters
STANDARD ELECTRICAL SPECIFICATIONS
MODEL SIZE
RESISTANCE
RANGE
RATED POWER
P25 °C
W
LIMITING ELEMENT
VOLTAGE UL
V
TOLERANCE
± %
TEMPERATURE
COEFFICIENT
± ppm/°C
RPS 250 250 0.24 to 1M (1) 250 5000 1, 2, 5, 10 150
73
56
6
RPS 250D ZA3
5.01
0
6
12 Ø
26 ± 1
16.2 57
34
Ø 7.2
Ø 4.2
8
.
5
3
2 x M4
USEFUL DEPTH: 6
73
56
6
RPS 250A ZA3
5
.
0
1
06
12 Ø
28 ± 1
18.7 57
Ø 7.2
Ø 4.2
38.1
2 x M4
USEFUL DEPTH: 6
MECHANICAL SPECIFICATIONS
Mechanical Protection Insulated case and resin for
potting UL 94 V-0
Resistive Element Cermet
Substrate Alumina onto aluminum base
End Connections Screws M4 (M5 on request)
Tightening Torque
Connections 2 Nm
Weight 170 g ± 10 %
ENVIRONMENTAL SPECIFICATIONS
Thermal Resistance Rth (j - c) 0.22 °C/W
Temperature Range -55 °C to 125 °C
Climatic Category 55 / 125 / 56
TECHNICAL SPECIFICATIONS
Power Rating
Chassis Mounted
250 W at 50 °C continuous
1000 W at 25 °C for 10 s
Temperature
Coefficient Standard
± 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
RPS 250
www.vishay.com Vishay Sfernice
Revision: 01-Dec-17 2Document Number: 50007
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
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 μm. In order to improve thermal conductivity, surfaces in contact (alumina,
heatsink) 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 four screws (not supplied).
• 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:
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 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
Rth (j - c) + Rth (c - h) + Rth (h - a) = = = 0.42 °C/W
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
PERFORMANCE
TESTS CONDITIONS REQUIREMENTS
Momentary Overload NF EN 140000 CEI 115_1
4 Pr / 10 s / UL = 5000 V < ± (0.25 % + 0.05 )
Rapid Temperature Change
NF EN 140000 CEI 68214 Test Na
5 cycles
-55 °C +125 °C
< ± (0.25 % + 0.05 )
Load Life NF EN 140000 CEI 115_1
1000 h Pr at 70 °C < ± (0.5 % + 0.05 )
Humidity (Steady State) MIL STD 202 Method 103 B and D
56 days RH 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) ± 250 ppm/°C ± 150 ppm/°C
Tolerance on Request ± 1 %/± 2 %/± 10 %
Tightening Torque on Heatsink RPS 250
3 Nm
PT
Rth (j - c)
Rth (c - h)
Rth (h - a)
++
------------------------- -------------------------- --------------------------- -----------------------=
T
P
-------
75
180
--------
RPS 250
www.vishay.com Vishay Sfernice
Revision: 01-Dec-17 3Document Number: 50007
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
OVERLOADS
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.
ENERGY CURVE
POWER CURVE
POWER RATING
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.
MARKING
Series, style, ohmic value (in ), tolerance in %,
manufacturing date, Vishay Sfernice trademark
OVERLOAD DURATION IN s
10-7 10-6 10-5 10-4 10-3 10-2 100
10-1
ENERGY IN JOULES
0.1
1
10
100
10 000
1000
POWER IN W
OVERLOAD DURATION IN s
1000
10 000
100 000
1 000 000
10 000 000
10-7 10-6 10-5 10-4 10-3 10-2 100
10-1
PACKAGING
Box of 15 units
RATED POWER IN %
0 20 40 60 80 100 120 140
HEATSINK TEMPERATURE IN °C
0
20
40
60
80
100
GLOBAL PART NUMBER INFORMATION
GLOBAL
MODEL STYLE DIELECTRIC OHMIC VALUE TOLERANCE PACKAGING TYPE
RPS250 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
0250DL2 2 J ZP SR R0B 3A
Legal Disclaimer Notice
www.vishay.com Vishay
Revision: 08-Feb-17 1Document Number: 91000
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