PRZEGLĄD ELEKTROTECHNICZNY, ISSN 0033-2097, R. 94 NR 6/2018 15 Mykhaylo ZAGIRNYAK, Dmytro MAMCHUR, Andrii KALINOV Kremenchuk Mykhailo Ostrohradskyi National University, Ukraine doi:10.15199/48.2018.06.03 An Algorithm for Induction Motor Monitoring System Based on Electrical Signals Analysis Abstract. In the paper it was developed indexes for evaluation induction motor (IM) current operational conditions basing on electrical signals analysis. Basing on these indexes it were derived logical rules for evaluation IM operational conditions, which were laid down in the basic of algorithm for IM monitoring system. It were developed related software for monitoring system, and it was conducted experimental verification, which confirmed possibility of use derived indexes and logical rules for evaluation current IM operational conditions. Streszczenie. W artykule opracowano wskaźniki do ewaluacji bieżących warunków działania silnika indukcyjnego bazujące na analizie sygnałów elektrycznych. Bazując na tych wskaźnikach wyprowadzone zostały logiczne zasady ewaluacji warunków działania silnika indukcyjnego, stanowiące podwaliny do budowy algorytmu monitorowania sinika indukcyjnego. Opracowany został program monitorujący oraz przeprowadzono weryfikację eksperymentalna, która potwierdziła możliwość użycia wyprowadzonych wskaźników i logicznych zasad ewaluacji bieżących warunków działania silnika indukcyjnego. (Algorytm systemu monitorującego silnik indukcyjny opartego na analizie sygnałów elektrycznych) Key words: electrical signals analysis, monitoring, diagnostics, software. Słowa kluczowe: analiza sygnałów elektrycznych, monitorowanie, diagnostyka, oprogramowanie Introduction Modern technologies allow one ensure comprehensive control of production operation, which increase its reliability and efficiency. However, sudden failures of operational equipment could lead to production breaks, which, in turn, lead to financial losses. As induction motors (IM) are used to drive predominant number of actuating mechanisms, theirs failures cause most significant financial losses and could lead to failure of other industrial equipment. In order to avoid significant financial losses due to production stoppage because of sudden IM failure it is reasonable to use monitoring systems at important parts of production process. Such systems should use data for analysis which could be easily measured and don’t need expensive additional equipment. The best choice, in this case, is collection data from electrical signals for further analysis. As it was stated in [1], induction motor diagnostics and monitoring, as well as its life forecast and necessity of maintenance, could be done basing on analysis of electrical energy transformation process. One of the features describing energy processes in IM is its power consumption. This signal is quite suitable to be chosen as a basis for IM diagnostic and monitoring system, as it doesn’t require suspension of production, and needs only motor’s measured currents and voltages, while all the rest necessary features could be computed indirectly. Moreover, power spectra signal analysis is more reliable than current spectra analysis and contain additional information which could be used for evaluation current motor technical conditions [2]. In [3] it were derived mathematical expressions for determination power spectra frequencies related to most frequently caused IM damages. However, low-quality of supply mains, electrical disturbances and simultaneous presence of several damage types could cause difficulties in diagnostics basing on these frequencies. Thus, there is necessity to develop some addition diagnostic features to improve reliability of IM monitoring and diagnostics basing on power signal analysis. Problem statement Development of indexes and algorithm for monitoring IM technical conditions aiming to avoid sudden failures and predict its remaining lifetime. Indexes for induction motor monitoring system based on power signal analysis The supply mains quality influence significantly on the waveform and features of instantaneous power signal, and could be estimated basing on normalized quality factors [4]. Thus, it is necessary to fulfill a complex analysis of IM damages and supply mains low quality influence on power consumption waveform. To meet this goal it is reasonable to develop diagnostic factors based on the analysis of change the features and waveform of three phases power consumption signal. These factors should vary in well- defined ranges and should contain information about reason of power signal waveform change and level of overall motor’s condition deterioration. Also these factors should take into account current load or rated value of controlled feature. It is reasonable to fulfill initial analysis basing on power consumption spectra, total three phases signal, as well as separately for each phase. Total three phases power consumption for healthy motor fed by ideal supply represented on a time-chart as straight line. Significant variable component usually indicates whether motor or load malfunction, thus addition analysis, aimed to detect its source, should be done. Experimental data analysis showed, that IM operation under total variable components value more than 10% of rated power indicated motor unsatisfactory operation condition. To take this into account, it was proposed to use higher power harmonics index: (1) н 1 N 1 2 Рhh P P K       , where r P – rated power;  P – amplitude value of  -th power harmonic. For healthy motor fed by ideal power source this index is equal to zero. It takes into account value of variable component relating to rated signal value, which allows one to estimate appropriateness of further motor operation under current operational conditions. In addition, it could be used following indexes. Power index of polyharmonic current and voltage signals: (2)      1 K 1 k 2 k 2 0 0 Q P P K  , where 0 P – power signal constant component;        1 K 0 k n m n m k Ua Ib Ub Ia Q – reactive power of k -th