Cement Coated
Wirewound Resistors
W30 SERIES
● 1% Tolerance
● Flameproof cement coating
● All welded construction
● High reliabilty
● Ideal for automotive applications and
power supplies
Electrical Data
W31
NOTES
Power rating at 25°C
watts
3.0
Power rating at 70°C
watts
2.5
Resistance range
ohms
0.01 to 10k
TCR (-55 to 155°C)
ppm/°C
See below
Resistance tolerance
%
5 2 1
Standard values
E24 series preferred
Other values to special order
Thermal impedance
°C/watt
83
Ambient temperature range
°C
-55 to 155
Limiting element voltage
volts
100
TCR
ppm/°C
0.01 ohms
<1000
0.033 ohms
<500
0.091 ohms
<200
10 ohms
<150
10K ohms
<100
Physical data
Dimensions (mm) and Weight (g)
Wt.
Type
L max.
D max.
f min.
d nom.
nom.
W31
13
5.6
22.75
0.8
1.0
CONSTRUCTION
A high quality ceramic substrate is assembled with
interference fit end caps to which are welded the element
winding and termination wires. The protection is then
applied to the body, providing an effective seal which is
impervious to moisture, shock, vibration, fungus and salt
spray.
TERMINATIONS
Material
Solder-coated copper clad steel wire.
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.
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
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.
L
D
f
d dia
MARKING
W31 resistors are legend marked with type reference,
resistance value and tolerance. Values are marked in
accordance with IEC 62.
SOLVENT RESISTANCE
The body and marking are resistant to all normal industrial
cleaning solvents suitable for printed circuits.
FLAMMABILITY
The resistor coating will not burn under any condition of
applied temperature or component overload.