Compact Flameproof Power

Wirewound Resistors

WP-S Series

Welwyn Components

Performance Data

Maximum

Typical Change

Load at rated power: 1000hrs @ 25°C

5 +0.001

Ω

3

Dry heat: 1000hrs @ 200°C

5 +0.001

Ω

3

Short term overload (5 x Pr for 5s)

5 +0.001

Ω

1

Derating from rated power @25°C

Zero at 280°C

Climatic

5 +0.001

Ω

2

Climatic category

55/200/56

TRC & Vibration

5 +0.001

Ω

1

Robustness & solder heat

5 +0.001

Ω

1

Long term damp heat (56 days)

5 +0.001

Ω

1

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

Terminations

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.

Marking

The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits.

Solvent Resistance

The resistor coating will not burn or emit incandescent particles under any condition of applied temperature or power overload.

Flammability

The pulse energy capacity limits in the graph below relate to pulses below 100ms duration, low mean power dissipation and at

25ºC.

Pulse Performance

Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com

Issue E · 07.06

100

WP-S Short Pulse Energy Capacity

Value (ohms)

10

1

0.1

0.1

1

10

100

1000

10000

WP7S

WP5S

WP4S

WP3S

WP2S

WP1S

WP25S