Vitreous Enamelled
Wirewound Resistors
W20 SERIES
●
All welded construction
●
High purity ceramic substrate
●
Impervious lead free vitreous enamel coating
●
High power dissipation for size
●
High stability and reliability
●
Suitable for harsh environments
●
Overload characteristics ideal
for protection circuits
Electrical Data
Commercial
Power rating at 25°C
Resistance range at
1% tolerance
2% tolerance
5% tolerance
watts
ohms
ohms
ohms
pp/°C
Style
watts
watts
ohms
ohms
ohms
ppm/°C
W21
3.0
1 to 10k
0.5 to 10k
0.1 to 10k
W215
5.0
1 to 15k
0.5 to 15k
0.1 to 15k
Typically: <+75
W22
7.0
1 to 22k
0.5 to 22k
0.1 to 22k
W23
W24
10.0
14.0
1 to 60k
1 to 100k
1 to 60k
1 to 100k
0.15 to 60k
0.2 to 100k
Maximum: +200
TCR (-55° to 200°C)
Approved BS CECC 40-201-002
Power rating at 25°C
Power rating at 70°C
Resistance range at
1% tolerance
2% tolerance
5% tolerance
TCR (-55° to 200°C)
JB
HB
KB
LB
MB
2.9
5.0
7.0
10.0
14.0
2.5
4.3
6.0
9.0
12.0
1 to 10k
1 to 15k
1 to 20k
1 to 56k
1 to 100k
0.5 to 10k
0.5 to 15k
0.5 to 20k
1 to 56k
1 to 100k
0.1 to 10k
0.1 to 15k
0.1 to 20k
0.15 to 56k
0.2 to 100k
≥5
ohms < 10 ohms: ±400
≥10
ohms: ±200
Applicable to commercial and approved ranges
Limiting element voltage
volts
Standard values
Thermal impedance
°C/watt
Ambient temperature range
°C
100
160
200
500
E24 preferred. Other values to special order
88
58
44
29
-55 to 200
750
22
Physical Data
Dimensions
Type
W21
W215
W22
W23
W24
400
(mm) & weight (g)
L max
D max
12.7
5.6
22.0
7.0
22.0
8.0
38.0
8.0
53.5
8.0
f min
22.75
23.1
23.1
-
-
d nom
0.8
0.8
0.8
0.8
0.8
Wt.nom
1
2
2
3.5
5
d dia
D
L
f
Temperature Rise
°C
W21
W215
W22
W24
W23
CONSTRUCTION
A high purity ceramic substrate is assembled with interference fit end caps to which
are welded the termination wires. The resistive element is wound on the substrate
and welded to the caps; the vitreous enamel protective coating is then applied.
TERMINATIONS
Material
Copper clad steel wire, nickel plated and solder-coated.
Strength
The terminations meet the requirements of IEC 68.2.21.
Solderability
The terminations meet the requirements of IEC 115-1,–
Clause 4.17.3.2.
Length
W23’s and W24’s are not supplied on tape.
Minimum lead length is 30 mm.
MARKING
The resistors are legend marked with type reference, resistance value and tolerance.
Values are marked in accordance with IEC 62.
SOLVENT RESISTANCE
The body protection and marking are resistant to all normal industrial cleaning
solvents suitable for printed circuits.
300
200
100
0
0
5
10
15
20
Dissipation – Watts
General Note
Welwyn Components reserves the right to make changes in product specification without notice or liability.
All information is subject to Welwyn’s own data and is considered accurate at time of going to print.
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, England Tel: 01670 822181 Fax: 01670 829465 Web: http://www.Welwyn-TT.co.uk
Issue A 07/99
Vitreous Enamelled
Wirewound Resistors
W20 SERIES
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 data
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
µv/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
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
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 bbe supplied
preformed. Contact factory for details.
STANDARD QUANTITIES PER PACKAGE
Type
Ammo Pack
Reel
Small Box
W21 W215 W22
1000 750
500
1000 750
700
N/A
N/A
N/A
W23
N/A
N/A
50
W24
N/A
N/A
25
116
Derating Curve
% of Rated Power
100
54
0
25
70
200
315
Ambient temperature
°C
the resistor body and the printed circuit board or
other components to ensure these are not over
heated. Resistance is measured 6mm from body.
10
±
0.5
f
1
6
f
2
A
f
1
– f
2
≤
1.4 mm
A
63±2
73±2
73±2
6
Type
W21
W215
W22
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, England Tel: 01670 822181 Fax: 01670 829465 Web: http://www.Welwyn-TT.co.uk
Issue A 07/99
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