High Voltage Precision
Thick Film Resistors
T Series
Welwyn Components
Working voltage up to 100kV
Resistances up to 50G
TCR down to 25ppm
Termination variants
Sets of resistors with matched characteristics
Electrical Data
T43
Power rating at 20°C
Resistance range
Limiting element voltage
TCR
Resistance tolerance
Values
Thermal impedance
Ambient temperature range
°C/watt
°C
31
watts
ohms
volts
ppm/°C
%
1.5
10K to 10G
4K
8K
T44
3.5
10K to 50G
14K
28K
100 *
1, 2, 5
E24 preferred values
27
-55 to 150
* Contact factory for 25 or 50ppm/°C
13
T48
10
33K to 50G
50K
100K
In air
In oil
Values > 1G: TCR is 250ppm/°C
Closer tolerances over restricted range
Any value to special order
Notes
Physical Data
Dimensions (mm) & Weight (g)
PCB
Type
T43D
T44D
T48D
T43KU
T44KU
T48KU
T43TU
T44TU
T48TU
L max
25.4
50.8
150.0
30.2
53.2
152.2
32.6
55.6
154.8
D max
8.4
8.4
8.4
8.5
8.5
8.5
8.5
8.5
8.5
f min
32.0
32.0
32.0
32.0
32.0
32.0
d nom
0.8
0.8
0.8
0.8
0.8
0.8
mounting
centres
31.8
57.2
156.4
Min
Bend
Radius
1.2
1.2
1.2
Wt. nom
3.1
5.6
18.5
3.9
7.4
19.3
5.8
8.2
20.2
T44TU
L
T44KU
L
d
D
T44D
L
f
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.
A subsidiary of
TT electronics plc
07.11
© 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
High Voltage Precision
Thick Film Resistors
T Series
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.
Solderability:
Welwyn Components
The terminations meet the requirements
of IEC 115-1, Clause 4.17.3.2.
Screw Terminations:
Styles TU and KU.
Material:
Screw Thread:
Turned brass.
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.
All KU & TU resistors are supplied with 8
mm long screwed brass studs.
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:
Strength:
Solder coated copper wire.
The terminations meet the requirements
of IEC 68.2.21
Coupling Stud:
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.
Performance Data
Maximum
Load at rated power: 1000 hours at 20°C
Shelf life: 12 months at room temperature
Derating from rated power at 20°C
Noise (in a decade of frequency)
Voltage coefficient of resistance
µV/V
ppm/V
∆R%
∆R%
≤
IG:3, >IG:5
0.3
Zero at 150°C
<2.5
<1
Typical
0.3
0.1
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.
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 1kΩ, 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.
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.
Packaging
Resistors are supplied packed in boxes.
Standard Quantities Per Box
All Types
10 or 20 per box
© 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
07.11
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