Chassis Mounting
Wirewould Resistors
WH SERIES
●High quality ceramic substrate
●All welded construction
●Anodised extruded aluminium case
●High power dissipation for size
●Suitable for severe environments
●Designed for excellent thermal conductivity
to heatsink
Electrical Data
WH5 EH10 WH25 WH50 NOTES
Power rating at 25°C watts 10 15 25 50* Mounted on
standard heatsink
Resistance range ohms 0.01 to 10k 0.01 to 20k 0.01 to 44k
0.015 to 120k
TCR (-55° to 200°C) ppm/°C <10Ω: ±75 ≥to <100 : ±50 ≥100Ω: ±25
Resistance tolerance % 1, 2, 5, 10
Low value limits ohms 1 at 1% 0.5 at 2% 0.05 at 5% 0.01 at 10% WH50 0.015 at 10%
APPROVED CECC 40203 - 006 AA BA CA DA
Power rating at 25°C watts 10 15 25 40 Mounted on
standard heatsink
Resistance range ohms 0.05 to 3.4k 0.05 to 15k 0.05 to 33k
0.05 to 82k
TCR (-55° to 200°C) ppm/°C ≥5Ω≤10Ω± 100 >10Ω±50
Resistance tolerance % 1, 2, 5
Low value limits ohms 1 at 1% 0.5 at 2% 0.05 at 5%
Limiting element voltage volts 150 250 500 1250
Standard values E24 preferred range Other values
to special order
Thermal impedance °C/watt 16.0 10.0 6.0 3.5 Mounted on
standard heatsink
Operating temperature range °C -55 to 200
*For load at maximum rating mount on heatsink 30.5 cm x 30.5 cm x 1.5 mm
© 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.
CONSTRUCTION
Cap and lead assemblies are fitted to a high purity ceramic
substrate. The resistive element is wound onto the
substrate and welded to the caps. The wound rod is then
moulded and fitted into an aluminium housing to give
optimum stability and reliability.
TERMINATIONS
Material Solder dipped, 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
MARKING
The resistors are legend marked with type reference,
resistance value and tolerance. Values are marked in
accordance with IEC 62.
SOLVENT RESISTANCE
Resistor and marking withstand all accepted industrial
cleaning fluids.