Vitreous Enamelled
Wirewound Resistors
W20 Series
Solvent Resistance
The body protection and marking are resistant to all normal
industrial cleaning solvents suitable for printed circuits.
Welwyn Components
Flammability
All materials used in the construction of ‘W’ series resistors
are inorganic and inherently non burning.
Performance Data
CECC 40201-002
Requirements
Load at commercial rating: 1000 hrs at 25°c
Load at CECC rating: 1000 hours at 25°c
Dry heat: 1000 hours at 200°c
Shelf life: 12 months at room temperature
Derating
Short term overload
Climatic
Climatic category
Long term damp heat
Temperature rapid change
Resistance to solder heat
Vibration and bump
Noise (in decade of frequency)
Robustness
Insulation resistance
Voltage Proof
Pulse handling
∆
R%
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
µ v /v
∆R%
ohms
volts
5
5
not specified
1
5
55/200/56
5
1
1
1
not specified
1
not specified
not specified
Actual Performance
Maximum
Typical
5
3.5
5
3.5
2
1
0.03
0.02
see derating curve
1.0
0.2
0.5
0.2
0.05
0.02
0.5
0.2
0.25
0.03
0.25
0.05
zero
zero
0.4
0.05
>.1G ohm
>.1G ohm
500 min
500 min
data available by request
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.
116
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. Alternatives available by
special request are detailed in the table below. W23’s and
W24’s are available only as loose packed in boxes. W series
resistors can be supplied preformed. Contact factory for
details.
10
f
1
6
f
2
b
f
1
– f
2
≤
1.4 mm
6
Derating Curve
% of Rated Power
100
54
Type
W21
W215
W22
b
63±2
73±2
73±2
0
25
70
200
315
Ambient temperature
°C
© 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 [ WELWYN COMPONENTS LIMITED ]
