Search results

Filters

  • Journals
  • Date

Search results

Number of results: 4
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

An implemented impedance measuring instrument is described in this paper. The device uses a dsPIC (Digital Signal Peripheral Interface Controller) as a processing unit, and a DDS (Direct Digital Synthesizer) to stimulate the measurement circuit composed by the reference impedance and the unknown impedance. The voltages across the impedances are amplified by programmable gain instrumentation amplifiers and then digitized by analog to digital converters. The impedance is measured by applying a seven-parameter sine-fitting algorithm to estimate the sine signal parameters. The dsPIC communicates through RS-232 or USB with a computer, where the measurement results can be analyzed. The device also has an LCD to display the measurement results.

Go to article

Authors and Affiliations

José Santos
Pedro Ramos
Download PDF Download RIS Download Bibtex

Abstract

The paper presents an impedance measurement method using a particular sampling method which is an alternative to DFT calculation. The method uses a sine excitation signal and sampling response signals proportional to current flowing through and voltage across the measured impedance. The object impedance is calculated without using Fourier transform. The method was first evaluated in MATLAB by means of simulation. The method was then practically verified in a constructed simple impedance measurement instrument based on a PSoC (Programmable System on Chip). The obtained calculation simplification recommends the method for implementation in simple portable impedance analyzers destined for operation in the field or embedding in sensors.

Go to article

Authors and Affiliations

Grzegorz Lentka
Download PDF Download RIS Download Bibtex

Abstract

The authors paid particular attention to the problem of antenna impedance measurements in the RFID technique. These measurements have to be realized by using two ports of a vector network analyzer and dedicated passive differential probes. Since the measurement process and estimated parameters depend on the frequency band, operating conditions, type of the system component and antenna designs used, appropriate verification of the impedance parameters on the basis of properly conducted experiments is a crucial stage in the antenna synthesis of transponders and read/write devices. Accordingly, a systematized procedure of impedance measurements is proposed. It can be easily implemented by designers preparing antennas for different kinds of RFID applications. The essence of indirect measurements of the differential impedance parameters is discussed in details. The experimental verification has been made on the basis of a few representative examples.

Go to article

Authors and Affiliations

Piotr Jankowski-Mihułowicz
Grzegorz Pitera
Mariusz Węglarski
Download PDF Download RIS Download Bibtex

Abstract

Verification of electrical safety in low-voltage power systems includes the measurement of earth fault loop impedance. This measurement is performed to verify the effectiveness of protection against indirect contact. The widespread classic methods and meters use a relatively high value of the measuring current (5÷20) A, so that they are a source of nuisance tripping of residual current devices (RCDs). The meters dedicated to circuits with RCDs usually use an extremely low value of current (lower than 15 mA), which in many cases it is not acceptable in terms of the measurement accuracy. This paper presents a method of earth fault loop impedance measurement in 3-phase circuits, without nuisance tripping of RCDs – the concept of measurement, the meter structure and the experimental validation. The nuisance tripping is avoided in spite of the use of measuring current value many times higher than that of the rated residual current of RCDs. The main advantage of the proposed method is the possibility of creating values of measuring current in a very wide range, what is very important with regard to accuracy of the measurement.

Go to article

Authors and Affiliations

Stanisław Czapp

This page uses 'cookies'. Learn more