Rps 500, Vishay sfernice – C&H Technology RPS500 User Manual
Page 3
RPS 500
Power Resistors for Mounting onto a Heatsink
Thick Film Technology
Vishay Sfernice
Document Number: 50047
For technical questions, contact: [email protected]
www.vishay.com
Revision: 14-Nov-08
2
Note:
(1)
Resistors are not tested and guaranteed in cycling conditions
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 ratio:
P:
Expressed in W
ΔT:
Difference between maximum working temperature and room temperature.
R
TH (j - c)
: Thermal resistance value measured between resistive layer and outer side of the resistor. It is the thermal
resistance of the component: 0.11 °C/W.
R
TH (c - 4)
: 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.
RECOMMENDATIONS FOR MOUNTING ONTO A HEATSINK
Surfaces in contact must be carefully cleaned.
The heater 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 silicon grease (type
SI 340 Rhône-Poulenc or Dow Corning).
The fastening of the resistor to the heatsink is under pressure control of two screws tightened at 4 Nm for full power availability
The following accessories are supplied with each product:
2 off CHC M4 x 16/16 class 12.9 for heatsink mounting,
2 off TH M4 x 6/6 and 2 M4 contact lock washers for connections.
PERFORMANCE
TESTS
CONDITIONS
REQUIREMENTS
Momentary Overload
IEC 60115-1
2 Pr/10 s
U
L
= 5000 V
< ± (0.25 % + 0.05
Ω)
Rapid Temperature Change
IEC 60115-1/IEC60068-2-14 Test Na
5 cycles - 55 °C to + 125 °C
< ± (0.25 % + 0.05
Ω)
Load Life (Chassis Mounted)
IEC 60115-1
Pr (i.e. 500 W)/1000 h/70 °C (no cycling)
(1)
< ± (0.5 % + 0.05
Ω)
Humidity (Steady State)
MIL STD 202 Method 103 B and D
56 days 95% RH/40 °C
< ± (0.5 % + 0.05
Ω)
RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR
Ohmic
< 1
Ω
> 1
Ω
Standard Tolerance
± 5 %
± 5 %
Standard TCR (- 55 °C to + 125 °C)
± 300 ppm/°C
± 150 ppm/°C
Tolerance on Request
± 1 %, ± 2 %, ± 10 %
P
ΔT
R
TH j
c
–
(
)
R
TH c
a
–
(
)
+
[
]
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1
( )
=