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
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
26
± 1
16.5
73
56
Ø 7.2
10.5
5.7
35.8
2 M4 USEFUL DEPTH: 6
60
57
34
Ø 4.2
Note
• Tolerance unless stated: ± 0.2 mm
STANDARD ELECTRICAL SPECIFICATIONS
MODEL
RPS 250
Note
(1)
E24 series
SIZE
250
RESISTANCE
RANGE
0.24 to 1M
(1)
RATED POWER
P
25 °C
W
250
LIMITING ELEMENT
VOLTAGE
U
L
V
5000
TOLERANCE
±%
1, 2, 5, 10
TEMPERATURE
COEFFICIENT
± ppm/°C
150
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 %
Ø 21
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
L connections 7 kV
RMS
H connections 12 kV
RMS
10
6
M
50 nH
< 40 pF
< 120 pF
Dielectric Strength
MIL STD 202 (301),
min, 10 mA max.
Insulation Resistance
Inductance
Capacitance Resistor/
Ground
ENVIRONMENTAL SPECIFICATIONS
Thermal Resistance
Temperature Range
Climatic Category
Revision: 21-Jun-13
R
th (j - c)
0.22 °C/W
- 55 °C to 125 °C
55/125/56
Document Number: 50007
1
For technical questions, contact:
sfer@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
Momentary Overload
Rapid Temperature Change
Load Life
Humidity (Steady State)
CONDITIONS
NF EN 140000 CEI 115_1
4 Pr/10 s/U
L
= 5000 V
NF EN 140000 CEI 68214 Test Na
5 cycles
- 55 °C + 125 °C
NF EN 140000 CEI 115_1
1000 h Pr at 70 °C
MIL STD 202 Method 103 B and D
56 days R.H. 95 %
REQUIREMENTS
< ± (0.25 % + 0.05
)
< ± (0.25 % + 0.05
)
< ± (0.5 % + 0.05
)
< ± (0.5 % + 0.05
)
RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR
Ohmic Value
Standard Tolerance
Standard TCR (- 55 °C to + 125 °C)
Tolerance on Request
<1
±5%
± 250 ppm/°C
± 1 %/± 2 %/± 10 %
>1
±5%
± 150 ppm/°C
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).
Tightening Torque on Heatsink
RPS 250
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)
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).
R
th (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.
R
th (h - a)
: Thermal resistance of the heatsink.
Example:
R
th (c - a)
: for RPS 250 power dissipation 180 W at + 50 °C room temperature.
T
125 °C - 50 °C
75 °C
T
75
-
-
R
th (j - c)
+ R
th (c - h)
+ R
th (h - a)
=
------
=
-------
= 0.42 °C/W
P
180
R
th (j - c)
= 0.22 °C/W
R
th (c - h)
+ R
th (h - a)
0.42 °C/W - 0.22 °C/W
0.20 °C/W
Revision: 21-Jun-13
Document Number: 50007
2
For technical questions, contact:
sfer@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
P:
T:
R
th (j - c)
:
RPS 250
www.vishay.com
OVERLOADS
In any case the applied voltage must be lower than 2.5
U
n
.
U
max.
< 2.5
U
n
< 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.
Vishay Sfernice
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.
100
ENERGY CURVE
1000
RATED POWER IN %
80
60
ENERGY IN JOULES
100
40
10
20
1
0
0
0.1
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
20
40
60
80
100
120
140
HEATSINK TEMPERATURE IN °C
OVERLOAD DURATION IN s
POWER CURVE
10 000 000
PACKAGING
Box of 15 units
1 000 000
POWER IN W
MARKING
100 000
Series, style, ohmic value (in
),
tolerance in %,
manufacturing date, Vishay Sfernice trademark
10 000
1000
100
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
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
D
= Diagonal
connections
A
= Straight
connections
DIELECTRIC
H
= Dielectric
strength 12 kV
L
= Dielectric
strength 7 kV
OHMIC VALUE
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
TOLERANCE
F
=1%
G
=2%
J
=5%
K
= 10 %
PACKAGING
B
= Box, 15 pcs
N
= Box, 15 pcs
N/A
(1 to 14 pcs by box)
TYPE
Standard RPS250A
=
Blank
Standard
RPS250D =
ZA3
Special =
Blank
(for RPS250D) or as
applicable =
ZAx
Revision: 21-Jun-13
Document Number: 50007
3
For technical questions, contact:
sfer@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
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provided in datasheets and/or specifications may vary in different applications and performance may vary over time. All
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including but not limited to the warranty expressed therein.
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definitions and restrictions defined under Directive 2011/65/EU of The European Parliament and of the Council
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Please note that some Vishay documentation may still make reference to RoHS Directive 2002/95/EC. We confirm that
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Revision: 02-Oct-12
1
Document Number: 91000
