Two terminal dual source low frequency impedance bridge was configured using commercial voltage calibrators. The bridge performance was evaluated by measuring 1 to 1 resistance ratio at 1 kHz using 1 kΩ and 10 kΩ resistors. The AC resistance ratio was also measured at frequencies from 100 Hz to 100 kHz. The same bridge was used for measuring ratios of other impedance combinations by adjusting the phase between the voltage sources. This simple two terminal dual source impedance bridge proved its reliable and versatile measurement capability.
This paper presents the comparison among three methodologies of digital multimeter calibration, two established by Brazilian and international guides, and one developed by the Eletrobras Eletronorte Electrical Calibration Laboratory. In each methodology, aspects as number of calibration points, calibration time and reliability are evaluated.
This paper describes efforts done in UME aiming to provide efficient ac-dc transfer calibrations. Work includes design of the software and some hardware components.
The paper presents the instrument and the technique for adjusting and calibrating the inductive voltage divider. The technique is based on comparing two AC voltages of identical frequency. The instrument distinctive feature is extracting and measuring of small differentialmode signal of the voltages being compared within nanovolt and microvolt range against the background of large common-mode signal. The instrument features, its technical and metrological parameters are also considered.
To keep life on our planet sustainable, reduction of carbon dioxide emission is indispensable. Therefore, today optimal use of electrical energy and efficiency of the power consumption are two of the most important questions of industrial management. The power changes on the electrical network can be influenced through centralized ripple control system by different power companies. This paper summarizes the scientific achievements running in Northern Hungary paying special attention to its audio-frequency and radio-frequency controlled system . A number of important results of our new...
Today and in the future the measuring and analysing of electrical energy is a significant topic because its quality and consumption has more and more importance in scientific means and also practical. Since power frequency is fluctuating measurements must be synchronised to the network frequency to avoid spectral leakage error. In this paper two synchronisation methods are shown and compared.
In telecommunications, much efforts are spent nowadays to make ICT more Green. Rising energy costs, an economic slowdown and environmental awareness have introduced serious strategic challenges to enterprises worldwide. There are a variety of new and existing technologies available that aid in green IT, such as more efficient hardware that demand less power. In access networks, often the copper telephony network ensuring POTS is used to offer Digital Subscriber Line services to industry and private customers; e.g. to offer high bandwidth Internet access. The reduction of the electrical power...
The paper investigates the radiated emissions caused by the interaction between pantograph and overhead lines in electrical transportation systems, and their effects on the frequency band occupied by some used telecommunication systems. Transient amplitude, rise time and pulse duration are measured in time domain to obtain the associated empirical distributions; power spectrum and frequency content are calculated in the bands of interest; finally a time-frequency representation is used to track the evolution of spectral components over time.
In this paper is presented the method for comparison of high value resistance standards by using the modified Wheatstone bridge and picoammeter as current detector, instead of low-impedance current-sensing transimpedance amplifier. Basically, the resistance ratio r can be measured on nominal levels 1:1, 10:1 or 100:1, ensuring the traceability chain from the reference standards of 10 MΩ and 1 GΩ for the range of interest 10 MΩ to 100 GΩ.
The Josephson voltage standard and the quantum Hall resistance standard is a clear and solid basis to realize SI traceable calibrations for all electrical measurements of varieties of applications. However, the traceability link is necessarily required between the well-established SI ampere and the wide measurement range at application sites for routine calibration works. The step-up technology is a simple and useful method which can be applied in various electrical measurement fields.