High Voltage Precision

Thick Film Resistors

T Series

High Voltage Precision

Thick Film Resistors

T Series

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

07.11

Welwyn Components

Matched Sets

Matched sets can be supplied for use as precision voltage

dividers. These may be screwed together to form sticks and,

by selecting the KU type of termination, a wire connection

can be provided at each end of the stick.

Enquiries are welcomed for special resistors and sets when

resistor length, operating voltage or resistance value are

outside the catalogued range.

Application Notes

Due to the high voltage which can appear between the end

cap and any adjacent metal part, resistors should be mounted

at an adequate distance from other conductors.

An appropriate number of resistors may be screwed together

as a stick to provide an assembly which will be capable to

withstanding any desired voltage, providing no individual

resistor is subject to a greater stress or power dissipation than

is recommended in this data sheet, and that appropriate anti-

corona devices are fitted.

The axial termination should not be bent closer than twice

the diameter of the terminal wire from the body of the

resistor.

Construction

A ruthenium oxide based resistive film is fired onto the

surface of a high quality former. Turned brass end caps are

fitted. A Helical cut is made into the film to adjust its resistive

value and finally a protective sleeve is fitted to provide

mechanical protection and electrical insulation. Resistors for

use in oil or SF6, can be supplied with a lacquer protection

instead of the sleeve.

Terminations

Three styles of termination are available to permit resistors to

be screwed together in a series chain, with the end members

having axial wires for soldering.

Wire Terminations: Styles D and KU.

Non standard terminations available upon

request.

Material:

Solder coated 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.

Screw Terminations: Styles TU and KU.

Material:

Turned brass.

Screw Thread:

All caps are tapped UNF – 10 x 4.2 deep.

UNF – 10 is 32 TPI, 60°C thread angle,

4.72±0.07 mm outside diameter, 3.83

mm core diameter.

Coupling Stud:

All KU & TU resistors are supplied with 8

mm long screwed brass studs.

Marking

Type reference, resistance value, tolerance and date code are

legend marked. The resistance value conforms to IEC 62.

Solvent Resistance

The lacquer and the protective sleeve provide excellent

resistance to all normal industrial cleaning solvents suitable for

printed circuits.

Standard Quantities Per Box

All Types

10 or 20 per box

Maximum

Typical

Load at rated power: 1000 hours at 20°C

∆R%

≤

3

.

0

5

:

G

I

>

,

3

:

G

I

Shelf life: 12 months at room temperature

∆R%

0.3

0.1

Derating from rated power at 20°C

Zero at 150°C

Noise (in a decade of frequency)

µV/V

<2.5

Voltage coefficient of resistance

ppm/V

<1

Performance Data

When resistors are required to be potted, the preferred

encapsulant is a silicone compound.

For voltage dividers with a low resistance section below the

minimum available value of 1k

Ω, it is normal practice to use a

Welwyn resistor, RC Series, obtainable down to 1 ohm.

Oil Immersion

For some high voltage applications it is required to immerse

the components in oil or gas to reduce the effects of corona

and surface tracking. A special lacquer protected version of

the resistor is available, suitable for immersion in transformer

oil or SF6.

Packaging

Resistors are supplied packed in boxes.

Make Possible

07.14

General Note

TT Electronics reserves the right to make changes in product specification without notice or liability.

All information is subject to TT Electronics’ own data and is considered accurate at time of going to print.

© TT Electronics plc

www.ttelectronicsresistors.com