W artykule przedstawiono podstawowe informacje dotyczące zjawiska napięć i prądów łożyskowych w maszynach elektrycznych. Omówiono podstawowe zagadnienia dotyczące przyczyn występowania zjawisk zarówno w przypadku zasilania maszyny bezpośrednio z sieci jak i przy zasilaniu z przekształtników energoelektronicznych. Zaprezentowano również nowe metody ograniczania napięć łożyskowych bazujące na dodatkowym uzwojeniu pomocniczym nawiniętym wokół jarzma stojana oraz na uzwojeniu ekranującym umieszczonym wewnątrz klinów żłobkowych stojana.
EN
The article presents basic information on the phenomenon of bearing voltages and currents in electrical machines. The basic issues concerning the causes of the described phenomena were discussed, both in the case of powering the machine directly from the AC grid as well as in the case of powering from power electronic converters. New methods of limiting bearing voltages were also presented: based on an additional auxiliary winding wound around the stator yoke and on a shielding winding located inside the stator slot wedges.
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W pracy przedstawiono problemy występujące w układach napędowych z silnikami indukcyjnymi zasilanymi z falownika napięcia. Zwrócono uwagę na rosnącą liczbę uszkodzeń silników w napędach przekształtnikowych. Wskazano przyczyny wynikające z charakteru zasilania przekształtnikowego silnika. Główną uwagę poświęcono prądowi łożyskowemu, który odpowiada za większość awarii maszyn. Przedstawiono rodzaje prądów łożyskowych, wyjaśniając fizykę zjawisk. Wymieniono sposoby ochrony silników przed oddziaływaniem prądów łożyskowych. Zaprezentowano przykładowe rozwiązanie filtru składowej zerowej.
EN
The paper presents problems appearing in electrical drive systems with induction motors supplied from voltage inverters. Attention was drawn to the increasing number of motor faults in converter drives. The causes resulting from the nature of the converter power supply are indicated. The main attention was paid to the bearing current, which is responsible for the majority of machine faults. Types of bearing currents are presented as well as an introduction to explaining the physical phenomena. The methods of protecting motors against bearing currents were listed. An exemplary solution of the zero-component filter is presented.
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The paper presents problems appearing in electrical drive systems with induction motors supplied from voltage inverters. Attention was drawn to the increasing number of motor faults in converter drives. The causes resulting from the nature of the converter power supply are indicated. The main attention was paid to the bearing current, which is responsible for the majority of machine faults. Types of bearing currents are presented as well as an introduction to explaining the physical phenomena. The methods of protecting motors against bearing currents were listed. An exemplary solution of the zero-component filter is presented.
PL
W pracy przedstawiono problemy występujące w układach napędowych z silnikami indukcyjnymi zasilanymi z falownika napięcia. Zwrócono uwagę na rosnącą liczbę uszkodzeń silników w napędach przekształtnikowych. Wskazano przyczyny wynikające z charakteru zasilania przekształtnikowego silnika. Główną uwagę poświęcono prądowi łożyskowemu, który odpowiada za większość awarii maszyn. Przedstawiono rodzaje prądów łożyskowych, wyjaśniając fizykę zjawisk. Wymieniono sposoby ochrony silników przed oddziaływaniem prądów łożyskowych. Zaprezentowano przykładowe rozwiązanie filtru składowej zerowej.
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W artykule przedstawiono zagadnienie zmniejszenia prądów łożyskowych w układach napędowych z falownikami napięcia przez wprowadzenie zmian w algorytmie modulacji szerokości impulsów.
EN
The paper presents the problem of reducing bearing currents in the electric drives with voltage inverters, through changes in pulse width modulation algorithm.
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W artykule przedstawiono wyniki badań prądów łożyskowych w silnikach indukcyjnych dużej mocy. Badania przeprowadzono w specjalistycznym laboratorium przemysłowym zapewniającym rozruch bezpośredni silników indukcyjnych dużej mocy z sieci o napięciu 1000 V. Przedstawiono uszkodzenia łożysk pod wpływem prądów łożyskowych. Udowodniono, że podczas pracy silnika występują pewne zakresy temperatur i prędkości obrotowych, w których występują niebezpieczne dla łożysk impulsy prądu łożyskowego. Przedstawione wyniki badań naświetlają zagrożenia dla trwałości węzłów łożyskowych silnika oraz obciążenia.
EN
Results of investigating bearing currents in high power induction motors are presented in the paper. The tests have been carried out in specialized industrial laboratory, where it is possible to achieve direct start of high-power induction motors supplied from 1000 V network. The bearing damages due to bearing currents are demonstrated. It has been proven that when motor operates within definite range of temperature and rotational speed, impulses of bearing currents dangerous to the bearings appear. The presented research results describe damage hazard to durability of motor and load bearing units.
The negative influence of bearing currents on the durability of rolling bearings in the alternating current electric motors are shown. The reasons of bearing current formation in electric motors are given. Examples of bearing races damages of cooperating rolling bearing elements are presented. Analysis of dents distribution in the roller, roll-neck and ball bearing races are made. Different types of insulated bearings are presented as well, applied to bearing currents elimination. Conclusions drawn from laboratory researches are presented in chapter 6.
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Artykuł zawiera analizę uszkodzeń łożysk w silnikach indukcyjnych dużej mocy. Przedstawiono różne rodzaje uszkodzeń łożysk w badanych silnikach oraz przyczyny powstawania napięć wałowych i prądów łożyskowych. W rozdziale 5 przedstawiono wpływ asymetrii napięcia zasilania na wartość napięć wałowych. W artykule zaprezentowano wyniki wielu badań laboratoryjnych oraz wnioski wypracowane w czasie badań.
EN
The paper presents results of investigations aimed at bearing faults detection in high power induction motors. Different kinds of bearing damages arising in the considered motors are shown. The causes of occurring the shaft voltages and bearing currents are given as well. In Section 5 there is presented influence of the supply voltage unbalance on the shaft voltage values. The conclusions drawn from the laboratory tests are presented in Section 7.
The negative influence of bearing currents on the durability of rolling bearings in the alternating current electric motors are shown. The reasons of bearing current formation in electric motors are given. Examples of bearing races damages of cooperating rolling bearing elements are presented. Analysis of dents distribution in the roller, roll-neck and ball bearing races are made. Conclusions drawn from laboratory researches are presented in chapter 6.
The paper presents the influence of the air gap asymmetry on the values of shaft voltages and currents. The investigations were performed with use of high power induction motor dSKgw 315 L-4 of 300 kW rated power and 1000 V rated voltage. In the section 1 are presented sorts of threats caused by bearing currents. Sorts of eccentricity of electrical machines are presented in section 2. In the section 3 the laboratory measurement system is described and applied measurement methods are presented as well. The results of laboratory investigations are presented in section 4. Conclusions drawn from investigations are placed in section 5.
In the paper are discussed different kinds of parasitic phenomena occurring in PWM inverter driven induction motors. In the article describes methodes for limiting bearing currents and common-mode current in PWM drives. The paper also presents results of experimental researches. Conclusions drawn from laboratory researches are presented in chapter 7.
The paper presents results of researches aimed at bearing faults detection in the high power induction motors. In chapter 2 are presented the causes of shaft voltages and bearing currents forming. The figure 1 shows the graphical presentation of the bearing currents forming issue. In the chapter 3, on the figures from 2 to 10 are shown different kinds of bearing damages arising in considered motors. In the chapter 4 is presented description of laboratory stand. The figure 12 presents diagram of measuring system. In the chapter 5 is presented influence of supply voltage unbalance on the value of shaft voltages. In the chapter 6 waveforms of shaft voltages, and their Fourier transforms are shown in Fig. 16, 17. Conclusions drawn from laboratory researches are presented in chapter 8.
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Analiza historii silników indukcyjnych dużej mocy pracujących w napędach potrzeb własnych elektrowni zawodowych i elektrociepłowni wskazuje, że od wielu lat coraz częściej wymagana jest wymiana łożysk tocznych w tych silnikach. Uszkodzenia łożysk tocznych występują częściej z chwilą zastosowania zasilania silników z falowników PWM. Spowodowały one, że zagadnienie prądów łożyskowych w silnikach indukcyjnych jest problemem aktualnym. Należy jednocześnie zaznaczyć, że awarie silników spowodowane uszkodzeniami łożysk tocznych nie występują tak często.
EN
The negative influence of bearing currents on the durability of rolling bearings in the alternating current electric motors are shown. The reasons of bearing current formation in electric motors are given. Examples of bearing races damages of cooperating rolling bearing elements are presented. Analysis of dents distribution in the roller, roll-neck and ball bearing races are made. The method of calculation of angular and circumferential scale between dents in the rolling bearing races rings are presented.
The paper presents results of scientific reasearches of large power induction motors. In chapter 2 are presented the causes of bearing currents forming supplied from line voltage. The figure 2 are presented influence rotational speed on the bearings resistance. The figure 3 are presented bearing current density versus life curve. The figure 5 are presented equivalent measurement system. In the chapter 4.2 are presented laboratory results. Figures 8 and 9 show characteristics determining influence of avarage bearing temeperature, shaft voltage and rotational speed on bearing current. Conclusions drawn from laboratory researches are presented in chapter 5.
The paper presents results of researches aimed at bearing faults detection in the high power induction motors. In the chapter 2 is presented description of laboratory stand. In the chapter 3, on the figures from 2 to 9 are shown different kinds of bearing damages arising in considered motors. In the chapter 4 is presented influence of supply voltage unbalance on the value of shaft currents and voltages. The figure 10 presents diagram of measuring system. On the figures 12, 13 and 14 are presented waveforms of shaft voltages and currents as well as their Fourier transforms. In the chapter 5 is presented influence of number of motor start-ups on the value of bearing current. On the figure 17 are presented waveforms of shaft voltages and currents. Conclusions drawn from laboratory researches are presented in chapter 6.
The negative influence of bearing currents on the durability of rolling bearings in the alternating current electric motors are shown. The reasons of bearing current formation in electric motors are given. Examples of bearing races damages of cooperating rolling bearing elements are presented. Analysis of dents distribution in the roller, roll-neck and ball bearing races are made. The method of calculation of angular and circumferential scale between dents in the rolling bearing races rings are presented.
The paper presents research results dealing with bearing faults of high power induction motors.In the chapter 2 are presented simulation results, as an introduction to laboratory measurements. The harmonic analysis of the stator winding phase currents are shown In charter 3. In charter 4 are presented the causes of bearing currents forming during motor direct startup. The figure 3 shows the graphical presentation of the bearing currents forming issue. In charter 5 measurement results are discussed. Waveforms of shaft currents and voltages, and their Fourier transforms are shown in Fig. 5, 6 and 7. Equivalent circuit diagram for bearing current flow is presented in chapter 6, Fig. 9. Equivalent circuit diagram for bearing current flow is presented in chapter 6, Fig. 9. Conclusions drawn from laboratory researches are presented in chapter 8.
The application of high switching techniques improves the economic and technical parameters of induction motor drives. However, it has been discovered recently an adverse effect on a bearing assembly which is caused by destructive bearing currents EDM (Electrical Discharge Machining). Since the introduction of the IGBT technology there has been a documented increase in electrically induced bearing failures and shortening electrical life of bearings. In the paper it has been presented the statistical approach related to the distributions of EDM currents in drives with different filter configurations. Commonly used solutions for CM currents reducing are the line reactors and CM chokes. However, they increase risk of the appearance of EDM currents of higher amplitudes in shorter awaiting times. The CM transformer is a good choice for a simultaneous decreasing of the CM current and the risk of EDM currents. However, the best method of an elimination of bearing currents is a cancellation of its source - common mode voltage - at the output of the inverter. In a paper it has been presented so-called sinusoidal filter that assures nearly zero common voltage at the filter output, strongly damps common and differential EMI and eliminate bearing currents.
The paper presents analysis of forming of the induction motor bearing currents and leakage currents. In chapter 2 the causes at common-mode voltage and shaft voltage formation are described. That voltages are both the cause of EDM bearing currents forming. In chapter 3 are presented different types of parasitic phenomena caused by common-mode voltage. Internal capacitances of the induction motor is shown in Fig.5. Figure 8 shows EDM bearing currents formation. Leakage currents in induction motors supplied from PWM Inverter are presented in chapter 4. Chapter 5 describes methodes for limiting bearing currents in PWM drives.
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Paper presents analysis and investigations of the influence of electric motors supply from frequency converter on the rolling bearings failures. Samples of bearing's failures are presented (Fig. 1). Substitute model of rolling bearing (Fig. 2) and process of nucleation of bearing currents (Fig. 3) are presented. Results of service life of rolling bearing after current pulses are shown on Fig. 4. Figure 5 shows topography of surface of rolling bearing, Figure 6 - state of bearing raceway after 250h of service life.
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The problem of shaft voltage origination in electrical machines was known and studied already at the beginning of the past century. The shaft voltage can occur also by synchronous generator with exciting winding fed from static exciter. When we will not respect any specific designing and mounting principles it can happen to current flow through bearings. Conductive path is created by closed circuit compounded from motor frame, bearing shields, bearings and shaft. In the other cases it can be concerned a circuit consisted from winding, air gap, bearing, capacitance or possible capacitance of other parts against ground. Different parts of bearings can be damaged by these currents and so it comes to operation state deterioration. In our paper we want to show measuring results of small and large power motors.
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