Emil Vremera, Cristian Fosalau, Luciano Brunetti
Instrumentation Set-up for Characterisation of the Sensors Based on Amorphous Wires

High sensitivity, quick response, small size, non-contact sense and low-power requirement, make amorphous wires attractive for sensors and micro-sensors realization. Negative factors accompany magneto-impedance sensors based on amorphous wires. They must be compensated for an efficient use of the devices and therefore the behavior of the sensing element must be well characterized. The paper highlights most important characteristics of amorphous wires and proposes an instrumentation set-up based on vector-voltmeter analyzer useful for carrying out their measurement.

Wiesław Firczyk, Marian Jerzy Korczynski
Symptoms of Mechanical Faults Deduced from Analysis of Electrical Power Supply

An output mechanical power of electrical driving system is directly related to electrical power consumption; proportional relation. This direct relation is a foundation of concluding of failures, manufacturing imperfections, wear and tear of gears used in driving systems. The paper is devoted to consideration how to investigate abnormal mechanical states caused by mechanical parts (gears in this case) of driving system based on analysis of consumed electrical power. Driving systems for power transmission are using different gears boxes (reducers and multipliers), mainly are helical gear boxes. Most of gear use wheels with “teeth”. Shapes of teeth are no perfectly identical due to imperfection of mechanical treatment at the production process. As a result of long time of gear box running, teeth are loosing their original shapes. Cracks may arise and even tooth or teeth may be broken. Such situation should be predicted before gear box fail down. The symptoms of such situation are analysed in the paper. The uncertainty analysis is a key for successful deduction about the state of gear.

Karol Kuczynski, Adam Bienkowski, Roman Szewczyk
New Measuring System for Testing of the Magnetostrictive Properties of the Soft Magnetic Materials

This paper presents the newly developed measuring system for testing of the magnetostrictive properties of the soft magnetic materials. The semiconductor strain-gauge measurement technique is utilized in this system. As a result the high resolution of measurements was achieved. Moreover, due to utilization of the both strain-gauge bridge and fluxmeter the simultaneous measurements of the flux density B and the magnetostriction λ as the function of magnetizing field H is possible. For this reason developed measuring system creates a new possibility of determination of the B(H), λ(H) and λ(B) characteristics. These characteristics were never tested simultaneously before.

Călin Ciufudean, Constantin Filote, Adrian Graur, Daniel Popescu, Camelia Petrescu
Diagnosability of Electric Machines Using Randomized Modulation Supply

This paper proposes a diagnosis method for electric machine faults by measuring the harmonic spectrum of stator current. In our assumption an electrical machine is excited with a randomized modulation of switching in power converters for reducing filtering requirements and acoustic noise in motor drive applications. Therefore, we propose a new approach for modelling the randomized modulation is the availability of an explicit control of time-domain performance, in addition to the possibility of shaping the power spectrum of signal of interest. The tool used here for investigating and classifying the harmonic decomposition of disturbances is the Least-Squares Prony method. Further approaches of this new method, as well as an example are also discussed.

Wojciech Toczek
Testing Oscillators by Waveform Comparison with the Ideal Sine-Wave

In context of the oscillation-based-test (OBT) technique, a simple and low-cost method of testing oscillators by comparison of finite segment of waveform with the ideal sine-wave is presented. The method is based on the subtraction of two sigma-delta modulated signals with the aid of a 1-bit subtractor that employs oversampling based noise-shaping. An up/down counter extracts the average of the bit stream that is used as a fault signature. The simulation results on the example of the Van der Pol oscillator show that the proposed fault signature is sensitive to the frequency and amplitude deviations and is able to detect non-linear oscillation as well.