ETC WH25

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
Power rating at 25°C
watts
Resistance range
TCR (-55° to 200°C)
Resistance tolerance
Low value limits
ohms
ppm/°C
%
ohms
APPROVED CECC 40203 - 006
Power rating at 25°C
watts
Resistance range
TCR (-55° to 200°C)
Resistance tolerance
Low value limits
Limiting element voltage
Standard values
Thermal impedance
ohms
ppm/°C
%
ohms
volts
°C/watt
WH5
10
EH10
15
WH25
25
WH50
50*
0.01 to 10k 0.01 to 20k 0.01 to 44k 0.015 to 120k
<10Ω : ±75
≥ to <100 : ±50
≥100Ω : ±25
1, 2, 5, 10
1 at 1%
0.5 at 2%
0.05 at 5%
0.01 at 10%
AA
10
BA
15
CA
25
DA
40
NOTES
Mounted on
standard heatsink
WH50 0.015 at 10%
Mounted on
standard heatsink
0.05 to 3.4k 0.05 to 15k 0.05 to 33k 0.05 to 82k
≥5Ω ≤ 10Ω ± 100
>10Ω ± 50
1, 2, 5
1 at 1%
0.5 at 2%
0.05 at 5%
150
16.0
250
500
E24 preferred range
10.0
Operating temperature range °C
6.0
1250
3.5
Other values
to special order
Mounted on
standard heatsink
-55 to 200
*For load at maximum rating mount on heatsink 30.5 cm x 30.5 cm x 1.5 mm
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.
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
Chassis Mounting
Wirewound Resistors
WH SERIES
Physical Data
DIMENSIONS (MM)
Type
A
B
Max
±0.3
WH5
30.0
12.4
WH10
36.5
15.9
WH25
51.0
19.8
WH50
72.5
21.4
Type
G
H
Max
Dia ±0.2
WH5
9
2.4
WH10
11
2.4
WH25
15
3.3
WH50
16
3.3
C
±0.3
11.3
14.3
18.3
39.7
L
Max
17.0
21.0
29.0
51.0
E
Min
1.9
1.9
2.8
2.8
M
±0.5
4.3
5.2
7.2
7.9
F
Max
17
21
28
30
N
Max
1.8
2.2
2.6
2.6
Performance Data
Load at commercial rating: 1000 hrs at 25°C
∆R %
Load at CECC rating: 1000 hours at 25°C
∆R %
Dry heat: 100 hours at 200°C
∆R %
Derating from 25°C
Short term overload
∆R %
Climatic sequence
∆R %
Climatic category
Long term damp heat
∆R %
Temperature rapid change
∆R %
Resistance to solder heat
∆R %
Vibration and bump
∆R %
Noise (in decade of frequency)
µV/V
Insulation resistance.
ohms
Isolation voltage : WH5 and 10
volts AC peak
: WH25 and 50
volts AC peak
CECC
ACTUAL
40203-006 MAXIMUM
TYPICAL
1.0
1.0
0.4
1.0
1.0
0.4
1.0
1.0
0.4
Zero at 200°C
1.0
1.0
0.2
1.0
1.0
0.4
55/200/56
1.0
0.5
0.2
0.25
0.25
0.1
0.25
0.25
0.05
0.25
0.25
0-.025
Not specified
zero
zero
>1Gohm
>20Tohm
>100Gohm
1000 min
1500 min
2000 min
3000 min
NOTES
See application
notes
© 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
Chassis Mounting
Wirewound Resistors
WH SERIES
APPLICATION NOTES
L
W
H
REFERENCE
CM
CM
CM
AREA SQ. CM
AA, BA
15.5
10
5
410
CA, DA
18
13
5
544
Aluminium thickness 1mm
Reference chassis
MAXIMUM DISSIPATION (WATTS)
CECC 40203-006
CECC 40 STYLE
50
Reference aluminium heatsink dimension
40
°C
25
AT
544cm2
N
IO
AT
C
P
I
70°
ISS
AT
DD
ION
T
E
A
T
SIP
RA
25°C
DIS
ED
RAT
70°C
30
20
CA
CA
25°C
70°C BA
25°C
70°C AA
10
410cm2
H
5 10
50 100
500 1000
HEATSINK SURFACE AREA (cm2)
L
W
Derating must be applied when resistors are
mounted on a heat sink of smaller dimensions than
defined in the table for reference heatsink.
WH50 ONLY
To load at maximum commercial rating (50W) mount
on heatsink 30.5cm x 30.5cm x 1.5mm.
It is recommended that the resistor base should be
coated with silicone grease before mounting to
obtain the stated operating characteristics.
The grease increases thermal conductivity to the
heatsink.
After soldering care should be taken to ensure that
there are no flux residues on the moulding
compound, otherwise insulation resistance will be
reduced.
PACKAGING
Resistors are packed in plastic bags and boxed for
maximum protection.
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