The Josephson-Effect-Based Primary AC Power Standard at the PTB: Progress Report

Phys.-Tech. Bundesanstalt, Braunschweig
IEEE Transactions on Instrumentation and Measurement (Impact Factor: 1.79). 05/2009; 58(4):1049 - 1053. DOI: 10.1109/TIM.2008.2008862
Source: IEEE Xplore


This paper reports the incorporation of a Josephson waveform synthesizer (JWS) into the primary standard for AC electrical power at the Physikalisch-Technische Bundesanstalt (PTB). The increase to 10 V of the amplitude delivered by the JWS has allowed matching of the levels of the signals measured to determine the active, reactive, and apparent power-at the 120-V and 5-A level, which is also measured by the device under test. The inherent noise- and drift-free voltages delivered by the JWS allow calibration of the core sampling voltmeter of the PTB primary power standard with an uncertainty of 0.4 muV/V(k = 1) in 100 signal periods and as part of the measuring sequence.

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    • "An AC power standard performing a continuous calibration of the digital sampling system in every cycle of the measured signals was developed at PTB. A recently developed 10 V Josephson Waveform Synthesizer (JWS) has been incorporated into the PTB primary standard for AC electrical power [4]. The 10 V SINIS binary arrays are used for in-situ calibration of the digital sampling voltmeter (DVM), with corrections applied over short time intervals. "
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    ABSTRACT: The present PTB primary standard allows power measurements with a measurement uncertainty of about 2.5 μW / VA (k = 2). It operates at voltages up to 240 V and currents up to 10 A in the frequency range from 16 Hz up to some kHz. This paper gives a short overview of the working principle of the standard and recent improvements.
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    ABSTRACT: This paper describes a sampling system designed using a commercial sigma-delta analog-to-digital converter (Sigma-Delta ADC). In addition to characterization measurements using a conventional high-quality signal generator, a Josephson waveform synthesizer that provides ultimately noise- and drift-free voltages was used. To evaluate the suitability of this sampling system as part of a transfer power standard, additional comparisons of the root-mean-square (RMS) values measured were performed against a thermal converter and the primary power sampling standard at the Physikalisch-Technische Bundesanstalt, Braunschweig, Germany. Initial analysis of the measurement data shows an effective resolution in the range of 18-19 bits at an equivalent sampling rate of 64 kHz. The integral nonlinearity error of the system was measured to be within plusmn7 muV/V or one least significant bit at this resolution.
    No preview · Article · May 2009 · IEEE Transactions on Instrumentation and Measurement
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