Vitreous Enamelled
Wirewound Resistors
W20 Series
Vitreous Enamelled
Wirewound Resistors
W20 Series
© Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
Welwyn Components
CECC 40201-002 Actual Performance
Requirements Maximum Typical
Load at commercial rating: 1000 hrs at 25°C 5.35%R
Load at CECC rating: 1000 hours at 25°C R% 5 5 3.5
Dry heat: 1000 hours at 200°C R% 521
Shelf life: 12 months at room temperature R% not specified 0.03 0.02
Derating see derating curve
Short term overload R% 1 1.0 0.2
Climatic R% 5 0.5 0.2
Climatic category R% 55/200/56
Long term damp heat R% 5 0.05 0.02
Temperature rapid change R% 1 0.5 0.2
Resistance to solder heat R% 1 0.25 0.03
Vibration and bump R% 1 0.25 0.05
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Robustness R% 1 0.4 0.05
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Pulse handling data available by request
Performance Data
Flammability
All materials used in the construction of ‘W’ series resistors
are inorganic and inherently non burning.
b
f1f2
6
6
10
f1– f2 1.4 mm
Application Notes
The termination should not be bent closer than 1.6mm from
the body, and the recommended minimum bend radius is
1.2mm. The terminations are solderable to within 4mm from
the body. When cold, vitreous enamel has excellent insulation
resistance. In common with all insulants the specific resistance
of the enamel decreases with increase in temperature.
Therefore, resistors operated at near maximum temperature
cannot be classed as insulated and should not be used in
contact with any conducting material. Care must be taken
when determining clearance distance between the resistor
body and the printed circuit board or other components to
ensure these are not over heated. Resistance is measured
6mm from body.
25 70 200 315
116
100
54
0
Ambient temperature °C
Derating Curve
% of Rated Power
Type b
W21 63±2
W215 73±2
W22 73±2
Packaging
For W21 and W215 the standard method of packaging is
taped in Ammo Packs. For W22 the standard method of
packaging is taped and reeled. W23’s and W24’s are
available only as loose packed in boxes.
Solvent Resistance
The body protection and marking are resistant to all normal
industrial cleaning solvents suitable for printed circuits.
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SolventResistance
Thebodyproteconandmarkingareresistanttoallnormalindustrialcleaningsolventssuitableforprintedcircuits
Flammability
AllmaterialsusedintheconstruconofW20seriesresistorsareinorganicandinherentlynon-burning.
11.16
General Note
TT Electronics reserves the right to make changes in product speciîš±cation without notice or liability.
All information is subject to TT Electronics’ own data and is considered accurate at time of going to print.
© TT Electronics plc
http://www.ttelectronics.com/resistors
BI Technologies IRC Welwyn
data available at http://www.ttelectronics.com/themes/ttelectronics/datasheets/resistors/literature/Pulse-Overload_AN.pdf