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
W21
3.0
1 to 10k
0.5 to 10k
0.1 to 10k
W215
5.0
1 to 15k
W22
7.0
1 to 22k
0.5 to 22k
0.1 to 22k
W23
10.0
1 to 60k
W24
14.0
1 to 100k
1 to 100k
0.2 to 100k
Power rating at 25°C
Resistance range at
watts
ohms
ohms
ohms
pp/°C
1% tolerance
2% tolerance
5% tolerance
0.5 to 15k
0.1 to 15k
Typically: <+75
1 to 60k
0.15 to 60k
Maximum: +200
TCR (-55° to 200°C)
Approved BS CECC 40-201-002
Power rating at 25°C
Power rating at 70°C
Style
watts
watts
ohms
ohms
ohms
ppm/°C
JB
2.9
2.5
HB
5.0
4.3
KB
7.0
6.0
LB
10.0
9.0
MB
14.0
12.0
Resistance range at
1% tolerance
1 to 10k
0.5 to 10k
0.1 to 10k
1 to 15k
0.5 to 15k
0.1 to 15k
1 to 20k
0.5 to 20k
0.1 to 20k
1 to 56k
1 to 56k
0.15 to 56k
≥10 ohms: ±200
1 to 100k
1 to 100k
0.2 to 100k
2% tolerance
5% tolerance
TCR (-55° to 200°C)
≥5 ohms < 10 ohms: ±400
Applicable to commercial and approved ranges
Limiting element voltage
Standard values
Thermal impedance
volts
100
160
200
500
750
22
E24 preferred. Other values to special order
88
°C/watt
°C
58
44
29
Ambient temperature range
-55 to 200
Physical Data
Dimensions (mm) & weight (g)
Type
W21
W215
W22
W23
W24
L max
12.7
22.0
22.0
38.0
53.5
D max
5.6
7.0
8.0
8.0
f min
22.75
23.1
23.1
-
d nom
Wt.nom
0.8
0.8
0.8
0.8
0.8
1
2
2
3.5
5
d dia
D
L
f
8.0
-
CONSTRUCTION
400
300
200
100
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.
W215
W21
W23
W24
W22
TERMINATIONS
Material
Copper clad steel wire, nickel plated and solder-coated.
The terminations meet the requirements of IEC 68.2.21.
The terminations meet the requirements of IEC 115-1,–
Clause 4.17.3.2.
W23’s and W24’s are not supplied on tape.
Minimum lead length is 30 mm.
Strength
Solderability
Length
MARKING
The resistors are legend marked with type reference, resistance value and tolerance.
Values are marked in accordance with IEC 62.
0
0
5
10
15
20
Dissipation – Watts
SOLVENT RESISTANCE
The body protection and marking are resistant to all normal industrial cleaning
solvents suitable for printed circuits.
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