High Voltage Thick Film Resistors Welwyn Components F Series • • • • • Working voltage up to 28kV Resistance up to 150G Termination variants Sets supplied with matched characteristics Good ratio matching over wide voltage range Electrical Data F43 F44 Power rating watts 0.7 1.3 Resistance range ohms 2M to 100G 2M to 150G Limiting element voltage TCR 20° - 70°C volts 4K 14K In air volts 8K 28K In oil ppm/°C Resistance tolerance -2000 % Standard values Thermal impedance Notes °C/watt Ambient temperature range 2, 5, 10 Measured at 100 volts dc E24 preferred Any value to special order 44 °C 33 -55 to 100 Physical Data Dimensions (mm) & Weight (g) PCB Min. mounting Bend centres Radius Wt. nom Type L max D max f min d nom F43D 25.4 8.4 32.0 0.8 31.8 1.2 3.1 F44D 50.8 8.4 32.0 0.8 57.2 1.2 5.6 F43KU 30.2 8.5 32.0 0.8 3.9 F44KU 53.2 8.5 32.0 0.8 7.4 F43TU 32.6 8.5 5.8 F44TU 55.6 8.5 8.2 F44D d D L f F44TU F44KU L L 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 © Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com Issue B · 03.02 201 High Voltage Thick Film Resistors Welwyn Components F Series Construction Screw Terminations: Styles TU and KU The Cermetox® thick film is fired on to the surface of a high quality ceramic former. Turned brass end caps are fitted. A helical cut is made into the film to adjust its ohmic value and finally a sleeve is fitted to provide mechanical protection and electrical insulation. Resistors for use in oil SF6 can be supplied with a lacquer protection instead of the sleeve. Material: Turned brass Screw Thread: All caps are tapped UNF - 10 x 4.2 deep. UNF - 10 is 32 TPI, 60° 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. 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. Marking Wire Terminations: Styles D and KU Solvent Resistance Type reference, resistance value, tolerance and date code are legend marked. The resistance values conform to IEC 62. The lacquer and protective sleeve provide excellent resistance to all normal industrial cleaning solvents suitable for printed circuits. Non standard wire 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. Performance Data Maximum Load at rated power: 1000 hours at 20°C ∆R% Shelf life: 12 months at room temperature ∆R% Typical 5 1 0.5 Derating from rated power at 20°C Zero at 100°C Noise (µV/V in a decade of frequency) Voltage coefficient of resistance <2.5 ppm/V <25 Application Notes Mounting 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. Resistors may be screwed together to provide an assembly which will be capable of withstanding any desired voltage, providing no individual resistor is subjected to a greater stress or power dissipation than is recommended in this data sheet. 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 is available, suitable for immersion in transformer oil of SF6. When resistors are required to be potted, the preferred encapsulant is a silicone compound. Matched Sets Matched sets can be supplied for use as 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 vale is outside the catalogued range. Packaging All components are supplied in boxes. Standard Quantities Per Box All Types 10 or 20 per box For voltage dividers with a low resistance section below the minimum available value of an F43 resistors, it is entirely suitable to use an RC Series resistor, available down to 1 ohm. © Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com 202 Issue B · 03.02