Construction

The stability and reliability of this range of resistors result

from the use of best quality materials in the construction. A

high purity ceramic tube is matched with nickel chromium or

copper nickel alloy resistance tape and specially formulated

enamel, ensuring the resistors withstand repeated heat

cycling without damage. Connections between the resistance

element and terminations are welded; other connections are

brazed. Ferrules are anchored into the tubes with high

temperature adhesive.

Terminations

Lugs (Figure 2) Solder coated nickel iron. Denoted by prefix

‘U’ to size reference, thus: U412.

Pigtails (Figure 3) 14/.193 mm copper, 150 mm minium

length. Denoted by prefix ‘UP’ thus: UP412.

Vitreous Enamelled Heavy

Duty Tapewound Resistors

U400 Series

© 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

128

Issue D · 08.04

Welwyn Components

Maximum

Load: 1000 hrs at room temperature

∆R%

5

Shelf life:

12 months at room temperature

∆R%

1

Humidity: 56 days

∆R%

2

Ferrule, electrically live (Figure 4) Nickel plated brass.

Denoted by prefix ‘UC’ thus: UC412.

Ferrule, Electrically Isolated (Figure 5) Connection to

resistor via solder coated nickel iron lugs. Denoted by prefix

‘UCB’ thus: UCB412.

Marking

The resistors are legend marked with type reference,

resistance value, tolerance and manufacturing date code.

Value marking conforms to IEC 62.

Solvent Resistance

The vitreous coating and marking are resistant to all accepted

industrial cleaning fluids suitable for printed circuit boards.

Performance Data

Overload

Very few applications are alike and it is not practicable to

provide complete overload performance information in this

publication.

The curves in Figure 1 are for guidance only, and Welwyn

Components will give advice on specified applications.

The specification should define:

Peak power or current

Pulse duration and shape

Minimum time between successive pulses

Figure 2. Style U

Figure 6. Style UCT

Figure 3. Style UP

Figure 4. Style UC

Figure 5. Style UCB

Tapped Resistors

(Figure 6) A tapping band can be fitted to resistors when required.

Add ‘T’ to type reference when ordering, thus: UT412 or UCT412.

More than one band can be fitted to the larger resistors,

the maximum number depending on resistor body length.

U400_D.qxd

8/9/04

4:55 PM

Page 2

OBSOLETE