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In this paper, plans and progress of a Finnish collaboration towards direct closure of the quantum metro- logical triangle are presented. The experimental concept and the present status of the main components, including two possibilities of the single charge transport device, Bloch oscillating transistor (BOT) based null detector, and a thin-film cryoresistor, are described.
Quadrifilar resistors with nominal values of 100 Omega, 1000 Omega and 10000 Omega, as well as a 100 Omega coaxial resistor, have been realized and their frequency dependences have been calculated from their constructional parameters. With the aim of experimentally verifying correctness of mathematical models used in these calculations, frequency dependences of ratios of parallel equivalent resistances...
For the accurate measurement and calibration of the famous Tinsley 5685 AC standard resistors, a new type of Kelvin resistance bridge working over frequency range from DC to 100 kHz is described. At the same time, a bridge substitution technique is used in which the unknown Tinsley resistor is compared to the standard of AC/DC calculable resistor with double helix arrangement. Through this bridge...
Coaxial resistors with a calculable frequency dependence have been realized at PTB as a part of the chain from the DC quantized Hall resistance to the capacitance standard. The construction of resistors with nominal value of 1000 Omega and 1290.64 Omega is described. A modified construction of the original Haddad resistor allows a full dismantling while the outer shielding is intact, and the resistance...
This paper describes the design and characterization of a low voltage divider with 100:1, 1000:1 and 10000:1 ratios in which, if the divider is supplied with 10 V will provide 100 mV, 10 mV and 1 mV outputs of high stability, low noise, low output impedance and stable thermal EMFs whose effects can be further reduced.
This paper describes the calibration of a high voltage resistor divider, using a comparison method. A capacitive and electronic divider or a standard instrument voltage transformer serves as a standard. The difference is evaluated either by means of a special system or by means of a lock-in amplifier.
This paper describes our specially designed portable air enclosure for preserving the calculable AC transferring resistor. The inner space of enclosure is 300 mm times 250 mm times 300 mm. Through solving the Laplace equation of heat conduction in sphere region a worthy conclusion is obtained: When the dimension of the layer of temperature homogeneity approaches the geometrical mean of size of the...
A new type of coaxial shunts, with nominal current from 20 mA to 20 A have been designed at I.N.RI.M.. Different approaches have been used to built them, depending on their nominal current. In the currents between 100 mA and 20 A they are made as a disk structure, using either SMD resistors or manganin foils. In order to reduce stray effects, their structures have ideally no common magnetic interaction...
A key comparison of resistance standards at 100 Omega started in 2001. The pilot laboratory, seven national metrological institutes, and the BIPM participated in that comparison. The results of this comparison are reported.
The four-terminal resistance of commonly used Tinsley Type 5685A 100 Omega resistors can vary significantly depending upon how firmly the terminals are tightened. Our measurements show a resistance to change of 12 nOmega/Omega for one resistor to an extreme case of 8000 nOmega/Omega for another resistor for which the body of one current terminal could rotate relatively easily. These findings makes...
A new set of ac-dc resistance transfer standards are being developed for use in the BIPM quadrature bridge. These resistors use commercial thick film resistance elements, whose small ac-dc difference is calibrated against a calculable coaxial reference. The improved stability of the new resistors should reduce the overall uncertainty of the quadrature transfer.
A new and improved design of the JV current shunts for 30 to 100 mA has been developed. The new shunts use surface-mount resistors mounted in a star configuration. AC-DC difference less than 3 muA/A at 100 kHz and less than 5 muA/A at 300 kHz has been achieved. Calculated and measured values agree very well.
The ordinary equivalent circuit of the AC resistor is not exact enough when the parasitic parameters of the resistor are considered. At the same time, the traditional shielding with potential equal to the lower voltage terminal of the resistor will contribute additional parasitic capacitance to the resistor and will deteriorate the calculated result of AC/DC difference. Using an equi-potential shielding...
Precision standard resistors manufactured within the last two decades using improved construction techniques and materials, such as the resistance alloy Evanohm, have been shown to have excellent environmental characteristics. Power dissipation (or loading) effects in several types of resistors have been examined including specifically those made of Manganin and Evanohm, and with the resistor element...
We have designed and fabricated a set of twelve high value standard resistors of 10 MOmega, 100 MOmega and 1 GOmega nominal values. A subset of three of them were measured at NIST during January, 2008, showing to have good stability and design, a short settling time and an important voltage coefficient.
The paper discusses the magnetic field of calculable resistor of toroid type which influences the transform of AC/DC quantum Hall resistances standard. Theoretical models are built based on the complex logarithm transform function. Thus, the distribution of magnetic field can be obtained. It also displays the distribution of main magnetic flux and the leakage flux. Furthermore, the equations of boundary...
We propose a thin-film thermal converter with resistive sensing of the temperature rise of the heater. Vanadium oxide (VO2) is used for the sensing resistors. This paper shows the simulations used for the basic design. The high temperature coefficient of its resistivity and the optimization of the design envisage a sensitivity of 10 VldrW-1.
It must need to take off the cause of nonlinearity if someone needs a good resistor. The 3rd harmonic distortion voltages of three types of resistors were measured. In the next stage, the 3rd harmonic voltage is tested using by a bridge made on a printed circuit board (PCB) occurs current constriction effectively. It is very simple structure without contact barriers to consider the cause of nonlinear...
An AC magnetic flux density standard system was constructed for calibration in KRISS magnetometers and for the testing of the magnetic field characteristics of sensors and materials in the frequency range below 20 kHz. This system consists of an AC magnetic field converter, a Helmholtz coil, a voltage comparator, a voltmeter, a standard resistor, and a computer with a program for automatic measurement...
In this paper we present the uncertainty evaluation of a new cryogenic current comparator (CCC) bridge designed to compare two-terminal 1 MOmega and 10 MOmega standard resistors with the quantized Hall resistance (QHR) and then scale from these values to other values between 10 kOmega and 1 GOmega.
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