High Voltage Precision
Thick Film Resistors
T Series
sWorking voltage up to 100kV
sResistances up to 50G
sTCR down to 25ppm
sTermination variants
sSets of resistors with matched characteristics
T43 T44 T48 Notes
Power rating at 20°C
* Contact factory for 25 or 50ppm/°C
watts 1.5 3.5 10
Resistance range ohms 10K to 10G 10K to 50G 33K to 50G
Limiting element voltage volts 4K 14K 50K In air
8K 28K 100K In oil
TCR ppm/°C 100 * Values > 1G: TCR is 250ppm/°C
Resistance tolerance % 1, 2, 5
Closer tolerances over restricted range
Values E24 preferred values Any value to special order
Thermal impedance °C/watt 31 27 13
Ambient temperature range °C -55 to 150
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
07.11
A subsidiary of
TT electronics plc
Welwyn Components
Dimensions (mm) & Weight (g)
PCB Min
mounting
Bend
Type L max D max f min d nom centres Radius Wt. nom
T43D 25.4 8.4 32.0 0.8 31.8 1.2 3.1
T44D 50.8 8.4 32.0 0.8 57.2 1.2 5.6
T48D 150.0 8.4 32.0 0.8 156.4 1.2 18.5
T43KU 9.38.00.235.82.03
T44KU 4.78.00.235.82.35
T48KU 3.918.00.235.82.251
T43TU 8.55.86.23
T44TU 2.85.86.55
T48TU 2.025.88.451
Physical Data
L
D
f
d
LL
T44D
T44TU T44KU
High Voltage Precision
Thick Film Resistors
T 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
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% ≤3.05:GI> ,3:GI
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 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.
Packaging
Resistors are supplied packed in boxes.
High Voltage Precision
Thick Film Resistors
T 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
07.11
Welwyn Components
Ordering Procedure
Example: T44 wire-ended and sleeved at 4.7 gigohms and 5% tolerance -
T 4 4 D – 4 G 7 J I
Type
Termination
D
Wire / wire
KU
Wire / screw
TU
Screw / screw
Protection
Lacquered & Sleeved
H
Lacquered only (for use in oil or SF6)
Value (use IEC62 code)
Tolerance (use IEC62 code)
F
1%
G
2%
J
5%
Packing
I
Box
Standard
Note: Standard TCR is 100ppm/°C. Contact factory for 50 and 25ppm/°C grades.