T48D WELWYN [Welwyn Components Limited], T48D Datasheet - Page 2

• Manufacturer Part Number: T48D
• Description: High Voltage Precision Thick Film Resistors
• Manufacturer: WELWYN [Welwyn Components Limited]

194
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.
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.
Material:
Strength:
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.
© Welwyn Components Limited
Telephone: [phone] · Facsimile: [phone] · Email: [e-mail] · Website: www.welwyn-tt.com
Performance Data
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
Non standard terminations available upon
request.
Solder coated copper wire.
The terminations meet the requirements
of IEC 68.2.21
Bedlington, Northumberland NE22 7AA, UK
ppm/V
µV/V
R%
R%
Solderability:
Screw Terminations: Styles TU and KU.
Material:
Screw Thread:
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.
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 , 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.
Standard Quantities Per Box
All Types
Maximum
IG:3, >IG:5
0.3
The terminations meet the requirements
of IEC 115-1, Clause 4.17.3.2.
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.
Zero at 150°C
Welwyn Components
10 or 20 per box
Typical
<2.5
0.3
0.1
<1
Issue B · 03.02