PRECISION HADDAD-TYPE CALCULABLE RESISTORS J. Kucera, E. Vollmer, - PowerPoint PPT Presentation

Precision Haddad-type calculable resistors PRECISION HADDAD-TYPE CALCULABLE RESISTORS J. Kucera, E. Vollmer, J. Schurr CPEM 2008 1

Precision Haddad-type calculable resistors Motivation CPEM 2008 2

Precision Haddad-type calculable resistors Calculable resistor • Calculable frequency dependence � simple construction – Coaxial resistors • Resistance versus length of resistor – Bifilar, quadrifilar, octofilar resistors • Short time stability • Low Temperature coefficient and Load coefficient CPEM 2008 3

Precision Haddad-type calculable resistors Haddad type resistor Haddad’s resistor - Coaxial model – boundary conditions - Transmission line effect - Skin effect in the inner conductor - Thin high-resistive wire - Thick low-resistive support - Skin effect and eddy currents in the outer conductor CPEM 2008 4

Precision Haddad-type calculable resistors Construction of the new resistor CPEM 2008 5

Precision Haddad-type calculable resistors Connections in the inner conductor Available technology: • Spot welding – No local change of metallurgy • Hard soldering + soft tin-soldering – Silver layer added, aggressive flux used – cleaning – Linear frequency dependence? • Electrogalvanization + soft tin-soldering – Silver layer added, aggressive liquid used during process • Crimping – Materials not melted, higher contact resistance (up to 250 mOhm) CPEM 2008 6

Precision Haddad-type calculable resistors Spot welding IsaOhm 20 um & IsaOhm 100 um CPEM 2008 7

Precision Haddad-type calculable resistors Spot welding IsaOhm 100 um & Brass tube 1 mm CPEM 2008 8

Precision Haddad-type calculable resistors Hard soldered silver IsaOhm 100 um CPEM 2008 9

Precision Haddad-type calculable resistors Galvanized silver IsaOhm 100 um CPEM 2008 10

Precision Haddad-type calculable resistors Frequency dependence of the connection point Contact resistance as a function of freq = 1 … 100 kHz 25 delta R(f) - R(f=1000Hz) (mOhm) 20 0.2 mOhm / 1 kHz 15 10 5 0 -5 1000 100000 Frequency (Hz) 10x 100 um IsaOhm crimped 2x 20 um Isaohm hard-soldered 2x 20 um IsaOhm hard-soldered, 3.5 Ohm contact resistance Slope 0.2 mOhm / 1 kHz 0.2 mOhm ~ 0.2 ppm for 1 kOhm CPEM 2008 11

Precision Haddad-type calculable resistors Rnominal = 1290,64… Ohm CPEM 2008 12

Precision Haddad-type calculable resistors Results of comparison measurements • AC coaxial ratio bridge • Measurement Ra/Rb -1, uncertainty 1.8x10 -8 • Frequency range 1 to 5 kHz • HR 1000 and HRC 1000 compared with – Bifilar 1 kOhm – Vishay 1 kOhm HR 1000 – hard-soldered and spot-welded HRC 1000 – crimped and spot-welded CPEM 2008 13

Precision Haddad-type calculable resistors Comparison of BIF, HR, HRC BIF – Bifilar hard soldered, HR – Haddad hard soldered, HRC – Haddad crimped BIF1000/HRC1000 HR1000/HRC1000 1.0 0.9 0.8 0.7 Ra/Rb-1 x10 -6 (-) 0.6 0.5 0.4 0.3 0.2 0.1 0.0 -0.1 0 1000 2000 3000 4000 5000 6000 Frequency (Hz) � large linear freq. dependence: Haddad type or BIF 1000? CPEM 2008 14

Precision Haddad-type calculable resistors Comparison of Vishay, HR, HRC Vishay – CTU in Prague, HR – Haddad hard soldered, HRC – Haddad crimped CTU 1k / HRC 1000 CTU 1k / HR 1000 CTU 1k / HRC 1000 repeat 0.03 0.02 Ra/Rb-1 x10 -6 (-) 0.01 0.00 0 1000 2000 3000 4000 5000 6000 -0.01 -0.02 -0.03 Frequency (Hz) � no significant frequency dependence for HR 1000 and HRC 1000 found CPEM 2008 15

Precision Haddad-type calculable resistors Characteristics of new Haddad resistors HR 1000 HRC 1000 HR 1290.6 Nominal value R ( Ω ) 1000 1000 1290.64 Resistance wire diameter ( µ m) 20 20 20 Resistance wire length (mm) 225 225 291 -0.26 ± 0.07 -1.74 ± 0.07 -0.52 ± 0.17 Temperature coefficient Tc (ppm/K), in air -384 ± 21 -343 ± 21 -389 ± 82.4 Load coefficient Lc (.10-9/mW), in air Frequency dependence dc-1.592 kHz, in air 4.09e-010 4.09e-010 4.15e-010 Frequency dependence dc-1.592 kHz, in sil. oil 4.38e-010 4.38e-010 4.96e-010 Measured values Calculations between potential ports plains CPEM 2008 16

Precision Haddad-type calculable resistors Excentricity of the inner conductor Eckhard Vollmer delta_R_o / R verursacht durch Wirbelstrom und Skin-Effekt im Außenleiter eines koaxialen, berechenbaren Widerstands (ANSYS für e = 0 und Beitrag nach Carter für e = 1 mm) 1.0E-03 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07 1.0E-05 1.0E-07 delta_R_o / R e = 0 mm 1.0E-09 e = 1 mm 1.0E-11 1.0E-13 1.0E-15 Frequenz in Hz CPEM 2008 17

Precision Haddad-type calculable resistors Conclusion • Modified Haddad resistor designed to have these advantages: – negligible freq. dependence – easily adjusted – can be dismantled • Two 1 kOhm and one 1.29064 kOhm resistors realized – with crimped, spot-welded and hard-soldered connection • Frequency dependence comparison with Bifilar 1 kOhm – large linear freq. dep. found in the bifilar resistor • Frequency dependence comparison with Vishay 1 kOhm – small freq.dep. of HR 1000 and HRC 1000 verified • Load and temperature coefficient determined • Frequency dependence of connection points tested – crimped, hard-soldered, spot-welded connections – no significant frequency dependence found CPEM 2008 18

Precision Haddad-type calculable resistors Acknowledgment • Thanks for helpful support and comments: J. Schurr, E. Vollmer, G. Muchow, P. Warnecke, V. Bürkel, P. Hinze, J. Kopton, B. H. Schumacher, G. Ramm, F. J. Ahlers, Bryan Kibble and others. • Financial and technical support: - PTB in Braunschwieg, Department 2.6 - Leonardo da Vinci programme "GOAL-S 2005-2007" CPEM 2008 19

Precision Haddad-type calculable resistors CPEM 2008 20