Compact Flameproof Power
Wirewound Resistors
WP-S Series
Welwyn Components
Terminations
Material:
Hot tin dipped copper 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
WP1S, WP2S, WP25S and WP3S resistors R10 and above are marked with four or five colour bands in conformance with IEC62.
Values below R10 are marked with three bands (two digits indicating value in milliohms, and tolerance); there is no multiplier
band. WP4S, WP5S and WP7S resistors are legend marked with type reference, resistance value and tolerance.
Solvent Resistance
The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits.
Flammability
The resistor coating will not burn or emit incandescent particles under any condition of applied temperature or power overload.
Performance Data
Maximum
5 +0.001Ω
5 +0.001Ω
5 +0.001Ω
Typical Change
Load at rated power: 1000hrs @ 25°C
Dry heat: 1000hrs @ 200°C
Short term overload (5 x Pr for 5s)
Derating from rated power @25°C
Climatic
∆R%
∆R%
∆R%
3
3
1
Zero at 280°C
55/200/56
∆R%
5 +0.001Ω
2
Climatic category
TRC & Vibration
∆R%
∆R%
∆R%
5 +0.001Ω
5 +0.001Ω
5 +0.001Ω
1
1
1
Robustness & solder heat
Long term damp heat (56 days)
Pulse Performance
The pulse energy capacity limits in the graph below relate to pulses below 100ms duration, low mean power dissipation and at
25ºC.
WP-S Short Pulse Energy Capacity
100
10
WP7S
WP5S
WP4S
1
WP3S
WP25S
WP2S
WP1S
0.1
10000
0.1
1
10
100
1000
Value (ohms)
© 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
Issue E · 07.06
TTELEC [ TT Electronics ]
