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This paper describes a setup to determine the temperature coefficient of standards inductors. Proposed method is based on Transformer Ratio Bridge and difference voltage measurement technique. The temperature coefficient of three inductors of value 1 mH (GR 1482) was measured by this method in the temperature range of 22degC to 27degC, which lies between 42 to 47 ppm/ degC with deviation of plusmn...
A switching device with low thermal electromotive forces is a core apparatus in all voltage standard laboratories where the unit must be maintained with high accuracy. Switching is essential in the pair intercomparison measurements required to maintain a voltage standard with multiple references and for the dissemination of the unit. Although various low- thermal switching equipment are available...
The following topics are dealt with: fundamental constant, resistance, ac-dc transfer, voltage, power, impedance, magnetic variable, time and frequency measurements and standards; calibration of measurement techniques and set-ups; photonic and magnetic methods; radiofrequency measurement methods.
Synthesizing Josephson stepwise sine waves to produce an AC quantum standard is limited by errors in the waveform transitions between quantized voltages. Many parameters have an impact on the shape of the transients. In this paper, the effect from microwave power and the position of the ground connection on the array chip are discussed.
A new dual-heater thermal voltage converter (DH- TVC) with improved low-frequency performance has been developed at the AIST. Frequency characteristic of the DH-TVC was evaluated using a dual-output programmable Josephson voltage standard(DO-PJVS), and was confirmed to have low-frequency flatness better than 10-6 down to 1 Hz.
A number of direct comparisons of Josephson Array Voltage Standards (JAVS) using Superconductor-Insulator-Superconductor (SIS) junction arrays have been performed at the National Metrology Centre (NMC), Singapore. The comparisons were performed over a range of voltage from 1 V to 10 V and with different combinations of array chips, both USA and German made. The comparisons used a parallel biasing...
This paper describes a compact, portable, high-precision voltage standard based on 1 V programmable Josephson array. The accuracy of the system is estimated to be better than 4 nV. The system can realize the fully automatic measurement of voltage reference, as well as its weight and volume are reduced. "In August, 2007 this system was carried to PTB, Germany to make a comparison. The difference...
A commercially available complete microprocessor controlled, fully automated 10 Volt Josephson voltage standard system was developed in cooperation between IPHT and Supracon. The system operates with an array of altogether 19,700 SIS Josephson tunnel junctions. A direct comparison between two such systems showed an uncertainty of 2 times 10-10. Furthermore, a novel cryocooler based system is described.
In high voltage testing there is a need to measure both the peak value and rms value of power frequency voltage. This paper describes method to calculate accurately both quantities; even when the frequency is not stable. The method can handle waveforms with harmonic content, and an uncertainty of few ppm can be achieved. Method is not sensitive to frequency fluctuation and phase lock loop is not needed.
Developed and approved in 2007 Secondary Standard of AC voltage scale transformation coefficient (VSTC) unit at primary rated voltages of 400 / radic3 kV and 500 / radic3 kV is described below.
A system for the precise measurement of electrical quantities by means of the rms value of ac voltages or currents is described. The system is implemented by a multijunction thermal converter and low cost electronic circuits. As a first application the system can both carry out ac voltage comparisons and ac and dc voltage measurements.
We have performed an experiment to drive an over-damped Josephson junction array (JJA) with modulated current pulse trains, which are generated by a modulated optical comb (an ultra-short pulse laser). The intensities of optical pulse trains are modulated using a pulse pattern generator. We quantitatively verified that the output voltages of the JJA were consistent with the modulation signals.
Digital sampling measuring system was developed at NIM. AC signals under test were transmitted into the input of AD converter by voltage follower. Under the control of MCU, AD converter synchronously sampled the signal by full period, and the sampling data was transmitted by photo-coupler and calculated by computer. The sampling results compared with the measurement results of FLUKE 5790A. The agreements...
A waveform synthesizer adopting a programmable Josephson voltage standard has been developed, which can produce stepwise sinusoidal waveforms with few hundred quantum voltage levels. For synthesis of waveforms, individual cells on the Josephson array chip were promptly biased using a 7-channel current source with 14-bit resolution. As an application, the synthesizer was utilized as a fast-reversed...
This paper describes the influence of the bias current on transients when synthesizing an AC signal using a programmable Josephson voltage standard. Measured changes of the RMS value of synthesized signals are compared with the presented model.
New thin-film range resistors have been developed at the National Metrology Institute of Japan (NMIJ) to reduce the voltage dependence of AC-DC transfer differences that have appeared in the processes of the step-up procedures over 300 V. The occurrence of voltage dependence is partly due to rising ambience temperature that may cause changes in the resistance of the resistor and the temperature dependence...
This paper presents the realization of a compact two- channel microcontroller-based digital synthesizer (CMDS) for generating accurate alternating (ac) voltage signals aiming at improving ac measurement techniques at AIST. Device description and the measurement techniques employed for evaluating it are described. First evaluations indicate that the CMDS may be used in high-grade ac Metrology.
This paper describes the implementation of a new quantum-based system for the generation of 120 V, 5 A, sinusoidal active and reactive power over the 50 Hz to 400 Hz frequency range. The system accurately relates the spectral amplitudes and phases of the voltage and current waveforms of the generated power to a programmable Josephson voltage standard (PJVS) using a novel differential sampling technique...
NIST is designing a 10 V Programmable Josephson Voltage Standard (PJVS) system with an improved microwave design and arrays of stacked NbxSi1-x-barrier Josephson junctions. For this new design a "ground-up" approach was used that takes into account all system issues in order to produce a robust 10 V system. By improving the uniformity of the microwave drive along the length of each array,...
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