A Multichannel FRA-Based Impedance Spectrometry Analyzer Based on a Low-Cost Multicore Microcontroller

Impedance spectrometry (IS) is a characterization technique in which a voltage or current signal is applied to a sample under test to measure its electrical behavior over a determined frequency range, obtaining its complex characteristic impedance. Frequency Response Analyzer (FRA) is an IS technique based on Phase Sensitive Detection (PSD) to extract the real and imaginary response of the sample at each input signal, which presents advantages compared to FFT-based (Fast Fourier Transform) algorithms in terms of complexity and speed. Parallelization of this technique has proven pivotal in multi-sample characterization, reducing the instrumentation size and speeding up analysis processes in, e.g., biotechnological or chemical applications. This work presents a multichannel FRA-based IS system developed on a low-cost multicore microcontroller platform which both generates the required excitation signals and acquires and processes the output sensor data with a minimum number of external passive components, providing accurate impedance measurements. With a suitable configuration, the use of this multicore solution allows characterizing several impedance samples in parallel, reducing the measurement time. In addition, the proposed architecture is easily scalable.

Dielectric Relaxation Studies in the Proton Conductors, Yb-Doped Ba(Ce,Zr)O3

Single-phase of BaCe0.57Zr0.38Yb0.05O2.975 (BCZYb) has been successfully prepared by a Pechini method using metal nitrate salts as pre-cursor. Dielectric behavior of the BCZYb sample was studied using impedance data collected from High Frequency Response Analyzer (HFRA). The frequency and temperature dependence of the dielectric constant and dielectric loss of the BCZYb solid solutions were investigated in the 1 Hz - 1 MHz frequency range. Dielectric relaxation mechanism was observed in the plots of dielectric constant and loss versus temperature. It was studied by the measurements of intermediate temperature, 500 - 800 ° C. All the responses were revealed by the analysis of impedance spectroscopy, using Z-man program. The present results are used to observe the relation between orientation polarization and dielectric relaxation of the material.

Fault location using Sweep Frequency Response Analysis in Disc type transformer winding

Winding faults are the leading cause of power transformer failures. Usually these failures develop in to more serious faults that would result in irreversible damage to the transformer winding and the consequential costs. This contribution is aimed at locating the faults by defining a set of two parameters based on change in impedance due to fault in the winding. Modeling and measurement of 22 kV continuous disc winding is done using circuit simulation package and sweep frequency response analyzer respectively.. The identified parameters are used in localization of faults in the transformer winding. The proposed method for localization of fault by measurement is validated by modeling.

Ionic behavior, Na+ mobility and infrared spectroscopy in Na7Cr4(P2O7)4PO4 material

The title compound, heptasodium tetrachromium(III) tetrakis(diphosphate) orthophosphate, was synthesized by solid state reaction. Its structure is isotypic with that of Na7M4(P2O7)4PO4 (M = In, Al) compounds and is made up from a three-dimensional [(CrP2O7)4PO4]7- framework with channels running along [001]. The Na+ cations are located in the voids of the framework. This compound has been investigated by X-ray diffraction and infrared (IR) spectroscopy. The conductivity measurements of the compound were carried out from 515 to 795 Kelvin using the frequency response analyzer with 0.05V amplitude signal over the range of 13MHz-5Hz. The conductivity of the sample at 574K is 0.45 10-6 S.cm-1. The activation energy Ea=0.73eV shows that Na7Cr4(P2O7)4PO4 is a medium ionic conductors. The monovalent cations conduction pathways in the crystal bulks are simulated by means of the bond valence model (BVS).

Microstructure, Mechanical and Electrical Properties of CuO Doped 8YSZ

The effect of the addition of a small amount of CuO on the microstructure, hardness, fracture toughness and electrical conductivity properties of 8YSZ were investigated using 8 mol% yttria-stabilized cubic zirconia (8YSZ). The addition of 1 wt% CuO to 8YSZ powders were doped using a colloidal process. Undoped and CuO doped 8YSZ specimens were pressureless sintered at 1400 °C for 10 h. The grain size measurement results showed that the presence of CuO as a intergranular second phase at the grain boundaries of the 8YSZ gave rise to a decrease in the grain size. The fracture toughness values for undoped and 1 wt% CuO-doped 8YSZ specimens were obtained as 1.79 and 2.20 MPa.m1/2, respectively. The decrease in the grain size of the 8YSZ with CuO addition caused an increase in the fracture toughness. The electrical conductivity of the undoped and 1 wt% CuO-doped 8YSZ specimens was measured using a frequency response analyzer in the frequency range of 100 mHz–13 MHz and at the temperature range of 300–800 °C. The electrical conductivity results showed that there was a decrease in the grain interior, and specific grain boundary conductivity, with the addition of a small amount of CuO to 8YSZ. The presence of a second phase layer with high resistance at the grain boundaries of the 8YSZ caused a decrease in the specific grain boundary conductivity.