Fast Fusible Metal

Film Resistors

WFF Series

• Low power fusing

• Predictable fusing characteristics

• Flameproof protection

WFF1/4

WFF1/2

WFF1

1

5

.

0

5

2

.

0

s

t

t

a

w

C

˚

0

7

t

a

g

n

i

t

a

r

r

e

w

o

P

5

K

1

-

2

R

0

K

7

2

-

0

1

R

0

K

0

1

-

1

R

0

s

m

h

o

e

g

n

a

r

e

c

n

a

t

s

i

s

e

R

0

5

3

0

5

3

0

5

2

s

t

l

o

v

e

g

a

t

l

o

v

t

n

e

m

e

l

e

g

n

i

t

i

m

i

L

0

5

2

C

˚

/

m

p

p

R

C

T

5

%

e

c

n

a

r

e

l

o

t

e

c

n

a

t

s

i

s

e

R

Standard values

E24 preferred

0

0

1

0

2

1

0

5

1

t

t

a

w

/

C

˚

e

c

n

a

d

e

p

m

i

l

a

m

r

e

h

T

5

5

1

o

t

5

5

-

C

˚

e

g

n

a

r

e

r

u

t

a

r

e

p

m

e

t

t

n

e

i

b

m

A

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, UK

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

Electrical Data

Issue D · 03.06

A subsidiary of

TT electronics plc

Welwyn Components

161

Construction

The metal film is deposited on a high purity ceramic rod. End

caps are force fitted and termination wires welded to the

caps. The resistive film is adjusted to the required value by a

special helical cut. A fuse aid coating is then applied. Finally a

cement protection is applied to the resistor body prior to

marking with indelible ink.

Terminations

Material

Solder-coated copper wire.

Strength

The terminations meet the requirements of

IEC68.2.21.

Solderability

The terminations meet the requirements of

IEC 115-1 Clause 4.17.3.2.

Marking

Resistors are colour coded with 5 bands. Four of the bands

are used to indicate values and tolerance, with IEC 62 colours

being used. A fifth yellow band denotes constant voltage

fusibility.

Solvent Resistance

The body protection and marking are resistant to all normal

industrial cleaning solvents suitable for printed circuits.

Flammability

The resistors will not burn or emit incandescent particles

under any condition of applied temperature or power

overload.

Dimensions (mm) & Weight (g)

Type

L

D

f

d

PCB

Min.

Wt.

max

max

min

nom

mounting

bend

nom

centres

radius

WFF1/4

6.2

2.3

21.0

0.6

10.2

0.6

0.3

WFF1/2

9.0

3.4

19.6

0.8

12.7

1.2

0.6

WFF1

12.5

4.2

17.8

0.8

18.4

1.2

0.9

Physical Data

L

D

f

d

2.5

Issue E · 01.07

OBSOLETE