Vitreous Enamelled

Wirewound Resistors

W20 Series

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

86

Issue C · 04.03

Welwyn Components

CECC 40201-002

Actual Performance

Requirements

Maximum

Typical

Load at commercial rating: 1000 hrs at 25°c

∆R%

5

3.5

Load at CECC rating: 1000 hours at 25°c

∆R%

5

5

3.5

Dry heat: 1000 hours at 200°c

∆R%

521

Shelf life: 12 months at room temperature

∆R%

not specified

0.03

0.02

Derating

see derating curve

Short term overload

∆R%

1

1.0

0.2

Climatic

∆R%

5

0.5

0.2

Climatic category

∆R%

55/200/56

Long term damp heat

∆R%

5

0.05

0.02

Temperature rapid change

∆R%

1

0.5

0.2

Resistance to solder heat

∆R%

1

0.25

0.03

Vibration and bump

∆R%

1

0.25

0.05

Noise (in decade of frequency)

µv/v

not specified

zero

zero

Robustness

∆R%

1

0.4

0.05

Insulation resistance

ohms

not specified

>.1G ohm

>.1G ohm

Voltage Proof

volts

not specified

500 min

500 min

Pulse handling

data available by request

Performance Data

Flammability

All materials used in the construction of ‘W’ series resistors

are inorganic and inherently non burning.

b

6

6

10

≤ 1.4 mm

Application Notes

The termination should not be bent closer than 1.6mm from

the body, and the recommended minimum bend radius is

1.2mm. The terminations are solderable to within 4mm from

the body. When cold, vitreous enamel has excellent insulation

resistance. In common with all insulants the specific resistance

of the enamel decreases with increase in temperature.

Therefore, resistors operated at near maximum temperature

cannot be classed as insulated and should not be used in

contact with any conducting material. Care must be taken

when determining clearance distance between the resistor

body and the printed circuit board or other components to

ensure these are not over heated. Resistance is measured

6mm from body.

Type

W21

W215

W22

W23

W24

Ammo pack

1000

750

500

n/a

n/a

Reel

1000

750

700

n/a

n/a

Small box

n/a

n/a

n/a

50

25

Standard Quantities Per Package

25

70

200

315

116

100

54

0

Ambient temperature

°C

Derating Curve

Type

b

W21

63±2

W215

73±2

W22

73±2

Packaging

For W21 and W215 the standard method of packaging is

taped in Ammo Packs. For W22 the standard method of

packaging is taped and reeled. Alternatives available by

special request are detailed in the table below. W23’s and

W24’s are available only as loose packed in boxes. W series

resistors can be supplied preformed. Contact factory for

details.

Solvent Resistance

The body protection and marking are resistant to all normal

industrial cleaning solvents suitable for printed circuits.

W20_C.qxd

28/4/03

10:19 am

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