General-Purpose Failsafe
Moulded Wirewound Resistors
SPH/SPF Series
Welwyn Components
•
Drop-in replacement for BWH/BWF
•
2 watt rated with 1 watt dimensions
•
±5%, ±10% tolerance
•
0.5 ohm to 2400 ohms
•
TCR’s as low as ±150 ppm/°C standard
(custom TC’s available)
•
Weldable and solderable leads
Electrical Data
Type
EIA RS-344 Style
MIL-R-11 Style
Resistance
Tolerance
Power rating
ohms
%
watts
0R5 to 2k4
±5, ±10
2 at 70°C
1 at 115°C
Derating to 0 at 160°C
Maximum continuous working voltage
Minimum insulation resistance
Minimum dielectric withstanding volts
Reduced pressure
Hotspot temperature rise
Current noise
dry
wet
ATM
RMS
watts
√PR
10,000 Meg
100 Meg
1000V
625V
145°C at 2 watts
Negligible
SPH
CRU2
RC32/RC42
0R5 to 1k
SPF
Physical Data
Dimensions (mm)
Type
SPH
SPF
L
14.3 ±0.25
14.3 ±0.25
D
5.72 ±0.20
5.72 ±0.20
d
0.813 ±0.05
0.813 ±0.05
f
38.1 ±3.2
38.1 ±3.2
d
D
L
f
Resistive Element
All resistor types have resistance alloy winding on a braided
fibreglass substrate. Intermediate silicone coatings are used to
enhance processibility and to provide protection to the
resistive element.
Encapsulation
The SPH and SPF are encapsulated utilizing a compression
moulded phenolic plastic material. The SPF has a flame-
resistance coating applied over the resistive element to provide
flammmability protection when destructive overloads may occur.
Termination
The SPH and SPF resistors are terminated using an alloy
coated copper flashed steel lead welded to a cap of the same
material. This termination assembly is mechanically crimped,
utilizing an improved crimp design, to the resistive element.
Marking
All products are marked utilizing heat and solvent resistant
colour code bands consistent with EIA/MIL requirements. The
first band is double width to designate wirewound construction.
A fifth band, blue in colour, is used for flameproof identification.
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.
A subsidiary of
TT electronics plc
Issue B · 03.02
© Welwyn Components Limited
· Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
93
General-Purpose Failsafe
Moulded Wirewound Resistors
SPH/SPF Series
Welwyn Components
Performance Data
SPH
Temperature coefficient (ppm)*
ohms
0.5 - 0.16 ±1000
0.18 - 0.68 ±800
0.75 -2400 ±400
Dielectric withstanding voltage
Momentary overload
Low temperature operation
Temperature cycle
Humidity
Load life
Terminal strength
Resistance to solder heat
RMS
%
%
%
%
%
%
%
700V
5
5
5
5
5
5
5
SPF
0.10 ±1700
0.11 - 0.16 ±1000
0.18 - 0.68 ±800
0.75 - 1000 ±400
*All ppm levels listed are maximum
SPH Power Derating
SPF Power Derating
Power (watts)
Ambient Temperature (°C)
Power (watts)
Ambient Temperature (°C)
SPF Typical Fusing
SPH & SFF Temperature Rise
Power (watts)
10 ohm
100 ohm
1000 ohm
Time (seconds)
Temp (°C)
0.1 ohm
1 ohm
Power Input (watts)
Packaging
Resistors are supplied taped and reel. 4,000 pcs per reel.
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
94
Issue B · 03.02
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