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Abstrakt

Designing touch-down bearings (TDB) for outer rotor flywheels operated under high vacuum conditions constitutes a challenging task. Due to their large diameters, conventional TDB cannot suited well, and a planetary design is applied, consisting of a number of small rolling elements distributed around the stator. Since the amplitude of the peak loads during a drop-down lies close to the static load rating of the bearings, it is expected that their service life can be increased by reducing the maximum forces. Therefore, this paper investigates the influence of elastomer rings around the outer rings in the TDB using simulations. For this purpose, the structure and the models used for contact force calculation in the ANEAS simulation software are presented, especially the modelling of the elastomers. Based on the requirements for a TDB in a flywheel application, three different elastomers (FKM, VMQ, EPDM) are selected for the investigation. The results of the simulations show that stiffness and the type of material strongly influence the maximum force. The best results are obtained using FKM, leading to a reduction of the force amplitude in a wide stiffness range.
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Bibliografia

  1.  L. Quurck, H. Schaede, M. Richter, and S. Rinderknecht, “High Speed Backup Bearings for Outer-Rotor-Type Flywheels – Proposed Test Rig Design,” in Proceedings of ISMB 14, Linz, Austria, 2014, pp. 109–114.
  2.  L. Quurck, D. Franz, B. Schüßler, and S. Rinderknecht, “Planetary backup bearings for high speed applications and service life estimation methodology,” Mech. Eng. J., vol. 4, no. 5, 2017, doi: 10.1299/mej.17-00010.
  3.  L. Quurck, R. Viitala, D. Franz, and S. Rinderknecht, “Planetary Backup Bearings for Flywheel Applications,” in Proceedings of ISMB 16, Beijing, China, 2018.
  4.  J. Cao, P. Paul Allaire, T. Dimond, C. Klatt, and J.J.J. van Rensburg, “Rotor Drop Analyses and Auxiliary Bearing System Optimization for AMB Supported Rotor/Experimental Validation – Part II: Experiment and Optimization,” in Proceedings of ISMB 15, Kitakyushu, Japan, 2016, 819–825.
  5.  J. Schmied and J.C. Pradetto, “Behaviour of a One Ton Rotor being Dropped into Auxiliary Bearings,” in Proceedings of ISMB 3, Zürich, Schweiz, 1992, pp. 145–156.
  6.  Z. Yili and Z. Yongchun, “Dynamic Responses of Rotor Drops onto Auxiliary Bearing with the Support of Metal Rubber Ring,” Open Mech, Eng. J., vol. 9, no. 1, pp. 1057–1061, 2015, doi: 10.2174/1874155X01509011057.
  7.  A. Bormann, Elastomerringe zur Schwingungsberuhigung in der Rotordynamik: Theorie, Messungen und optimierte Auslegung. Disser- tation. Düsseldorf: VDI-Verl., 2005.
  8.  M. Orth and R. Nordmann, “ANEAS: A Modeling Tool for Nonlinear Analysis of Active Magnetic Bearing Systems,” IFAC Proceedings Volumes, vol. 35, no. 2, pp. 811–816, 2002, doi: 10.1016/S1474-6670(17)34039-9.
  9.  V.L. Popov, Contact Mechanics and Friction: Physical Principles and Applications. Berlin, Heidelberg: Springer, 2017.
  10.  E.P. Gargiulo Jr., “A simple way to estimate bearing stiffness,” Machine Design, vol. 52, no. 17, pp. 107–110, 1980.
  11.  K.H. Hunt and F.R.E. Crossley, “Coefficient of Restitution Interpreted as Damping in Vibroimpact,” J. Appl. Mech., vol. 42, no. 2, p. 440, 1975, doi: 10.1115/1.3423596.
  12.  M.C. Marinack, R.E. Musgrave, and C.F. Higgs, “Experimental Investigations on the Coefficient of Restitution of Single Particles,” Tribol. Trans., vol. 56, no. 4, pp. 572–580, 2013, doi: 10.1080/10402004.2012.748233.
  13.  R.J. Mainstone, “Properties of materials at high rates of straining or loading,” Mat. Constr., vol. 8, no. 2, pp. 102–116, 1975, doi: 10.1007/ BF02476328.
  14.  H. Wittel, D. Muhs, D. Jannasch, and J. Voßiek, “Wälzlager und Wälzlagerungen,” in Roloff/Matek Maschinenelemente, H. Wittel, D. Muhs, D. Jannasch, and J. Voßiek, Eds., Wiesbaden: Vieweg+Teubner Verlag, 2009, pp. 475–525.
  15.  J. M. Gouws, “Investigation into backup bearing life using delevitation severity indicators,” North-West University, Potchefstroom, South Africa, 2016.
  16.  G. Sun, “Auxiliary Bearing Life Prediction Using Hertzian Contact Bearing Model,” J. Appl. Mech., vol. 128, no. 2, p.  203, 2006, doi: 10.1115/1.2159036.
  17.  T. Ishii and R. G. Kirk, “Transient Response Technique Applied to Active Magnetic Bearing Machinery During Rotor Drop,” J. Vib. Acoust., vol. 118, no. 2, pp. 154–163, 1996, doi: 10.1115/1.2889643.
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Autorzy i Afiliacje

Benedikt Schüßler
1
ORCID: ORCID
Timo Hopf
1
ORCID: ORCID
Stephan Rinderknecht
1
ORCID: ORCID

  1. Technical University of Darmstadt, Institute for Mechatronic Systems, Germany
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Abstrakt

The article presents the analysis results of the effectiveness limitation of the step voltage by forming an electric field on the ground surface. For shaping the electric field, a method consisting of screens placed around the point of the earth current flow was used. The analysis was performed using an example of an MV/LV substation grounding system. This research was conducted applying a mathematical model of the grounding system and screens by means of the finite element method. The influence of metal, insulating screens and surface material on the step/touch voltage values for the considered grounding system was estimated. Most of the methods described can be applied in practice. In the opinion of the authors, the method of using screens made of insulating and conductive materials has not been sufficiently described in the literature. Moreover, in the available literature there is no in-depth analysis of the described electric field shaping methods.
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Bibliografia

[1] Czapp S., Protection against electric shock in high voltage overhead electrical lines – present state of the standards, The Scientific Papers of Faculty of Electrical and Control Engineering Gdansk University of Technology (in Polish), ISSN 1425–5766, no. 35/2013, pp. 21–26 (2013).
[2] IEEE 80 Guide for Safety in AC Substation Grounding (2013).
[3] IEEE Std 665-1995 Standard for Generating Stations Grounding (1996).
[4] PN-EN 50522:2011 Earthing of power installations exceeding 1 kV a.c.
[5] Baka D.A., Uzunoglu K.N., Detecting and Avoiding Step Voltage Hazards, IEEE Transactions on Power Delivery, vol. 30, no. 6, pp. 2519–2526 (2015).
[6] Cardoso C., Rocha L., Leiria A., Teixeira P., Validation of an integrated methodology for design of grounding systems through field measurements (2017), DOI: 10.1049/oap-cired.2017.0452.
[7] Tang B., Huang Y., Liu R.,Wu Z., Qu Z., Fitting algorithm of transmission tower grounding resistance in vertically layered soil models, Electric Power Systems Research, vol. 139, pp. 121–126 (2016).
[8] Gazzanaa S.D., Bretasa S.A., Diasa A.D.G., Tellób M., ThomascW.P.D., Christopoulos C., A study of human safety against lightning considering the grounding system and the evaluation of the associated parameters, Electric Power Systems Research, vol. 113, pp. 88–94 (2014).
[9] Faleiro E., Asensio G., Denche G., Moreno J., Electric behavior of conductor systems embedded in finite inhomogeneous volumes scattered into a multilayered soil: The problem of High-Resistivity Ratios revisited, Electric Power Systems Research, vol. 148, pp. 183–191 (2017).
[10] Raizera A., Valente W.Jr., Luiz Coelho V., Development of a new methodology for measurements of earth resistance, touch and step voltages within urban substations, Electric Power Systems Research, vol. 153, pp. 111–118 (2017).
[11] Berberovic S., Haznadar Z., Stih Z., Method of moments in analysis of grounding systems, Engineering Analysis with Boundary Elements, vol. 27, pp. 351–360 (2003).
[12] Ma J., Dawalibi F.P., Southey R.D., On the equivalence of uniform and two-layer soils to multiplayer soils in the analysis of grounding systems, IEE Proc.-Gener. Transm. Distrib., vol. 143, no. 1 (1996).
[13] Ma J., Dawalibi F.P., Daily W.K., Analysis of grounding systems in soils with hemispherical layering, IEEE Transactions on Power Delivery, vol. 8, no. 4 (1993).
[14] Ma J., Dawalibi F.P., Analysis of grounding systems in soils with cylindrical soil volumes, IEEE Transactions on Power Delivery, vol. 15, no. 3 (2000).
[15] Grcev L.D., Heimbach M., Frequency dependent and transient characteristics of substation grounding systems, IEEE Transactions on Power Delivery, vol. 12, pp. 172–178 (1997).
[16] Zhang B., Jiang Y., Wu J., He J., Influence of Potential Difference Within Large Grounding Grid on Fault Current Division Factor, IEEE Transactions on Power Delivery, vol. 29, pp. 1752–1759 (2014).
[17] Trifunovic J.,Kostic M.B., An Algorithm for Estimating the Grounding Resistance of Complex Grounding Systems Including Contact Resistance, IEEE Transactions on Industry Applications, vol. 51, pp. 5167–5174 (2015).
[18] Report of the Substation CommitteeWorking Group 78.1, IEEE 80 Guide for Safety in A–C Substations – Review, IEEE Transactions on Power Apparatus and Systems, vol. 101, no. 10 (1982).
[19] Colominas I., Gómez-Calviño J., Navarrina F., Casteleiro M., Computer analysis of earthing systems in horizontally or vertically layered soils, Electric Power Systems Research, vol. 59, pp. 149–156 (2001).
[20] Androvitsaneasa P.V., Alexandridisb K.A., Gonosa F.I., Douniasc D.G., Stathopulos I., Wavelet neural network methodology for ground resistance forecasting, Electric Power Systems Research, vol. 140, pp. 288–295 (2016).
[21] Khodra H.M., Salloumb G.A., Saraivac J.T., Matosc M.A., Design of grounding systems in substations using a mixed-integer linear programming formulation, Electric Power Systems Research, vol. 79, pp. 126–133 (2009).
[22] Datsios Z.G., Mikropoulos N.P., Safety performance evaluation of typical grounding configurations of MV/LV distribution substations, Electric Power Systems Research, vol. 150, pp. 36–44 (2017).
[23] Jiansheng Y., Huina Y., Liping Z., Xiang C., Xinshan M., Simulation of substation grounding grids with unequal-potential, IEEE Transactions on Magnetic, vol. 36, no. 4 (2000).
[24] Meliopoulos A.P., Feng Xia, Joy E.B., Cokkinides G.J., An advanced computer model for grounding systems analysis, IEEE Transactions on Power Delivery, vol. 8, no. 1 (1993).
[25] Meng X., Han P., Liu Y., Lu Z., Jin T., Working temperature calculation of single-core cable by nonlinear finite element method, Archives of Electrical Engineering, vol. 68, no. 3, pp. 643–656 (2019).
[26] Wolnik T., Alternate computational method for induction disk motor based on 2D FEM model of cylindrical motor, Archives of Electrical Engineering, vol. 69, no. 1, pp. 233–244 (2020).

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Autorzy i Afiliacje

Roman Sikora
1
ORCID: ORCID
Przemysław Markiewicz
1
ORCID: ORCID

  1. Institute of Electrical Power Engineering, Lodz University of Technology, Stefanowski str. 18/22, 90-924 Lodz, Poland

Abstrakt

Artykuł proponuje reinterpretację ekspozycji zbiorów puławskich za pomocą szczegółowej analizy przywoływanych w założeniu kontekstów wergiliańskich. Dobór inskrypcji i antycznych symboli kształtujących narrację wystawienniczą, wraz z zachowanymi świadectwami recepcji owych strategii w puławskich pawilonach, ukazuje konsekwentne podważanie sekwencji chronologicznych, prymatu autentyczności i estetyzacji zbiorów. Anachroniczne dystansowanie się od temporalności historyzującej następuje na rzecz intymnego doświadczenia pamiątek (na)rodowych w zgodzie z kształtującą się ówcześnie kategorią fetyszu.
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Autorzy i Afiliacje

Aleksander Musiał
1
ORCID: ORCID

  1. Princeton University

Abstrakt

The touch trigger probe plays an important role in modern metrology because of its robust and compact design with crash protection, long life and excellent repeatability. Aside from coordinate measuring machines (CMM), touch trigger probes are used for workpiece location on a machine tool and for the accuracy assessment of the machine tools. As a result, the accuracy of the measurement is a matter of interest to the users. The touch trigger probe itself as well as the measuring surface, the machine tool, measuring environment etc. contribute to measurement inaccuracies. The paper presents the effect of surface irregularities, surface wetness due to cutting fluid and probing direction on probing accuracy on a machine tool.

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Autorzy i Afiliacje

Md. Mizanur Rahman
J.R.R. Mayer

Abstrakt

The article provides a theoretical basis for a method allowing to calculate probability of effects of electric shock, as well as a method for determining probabilistic characteristics of random touch current values and of human body impedance in a person who suffered from specific effects of electric shock. Results of example calculations are presented, including probabilities of occurrence of sensory symptoms, exceeding the letgo threshold, and development of ventricular fibrillation, as well as probabilistic characteristics of random touch current values and of impedance of human body in people who experienced specific effects of electric shock.

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Autorzy i Afiliacje

Włodzimierz Korniluk
Dariusz Sajewicz

Abstrakt

The article describes a shock safety modeling method for low-voltage electric devices, based on using a Bayesian network. This method allows for taking into account all possible combinations of the reliability and unreliability states for the shock protection elements under concern. The developed method allows for investigating electric shock incidents, analysing and assessing shock risks, as well as for determining criteria of dimensioning shock protection means, also with respect to reliability of the particular shock protection elements. Dependencies for determining and analysing the probability of appearance of reliability states of protection as well as an electric shock risk are presented in the article.
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Autorzy i Afiliacje

Włodzimierz Korniluk
Dariusz Sajewicz

Abstrakt

The article presents a shock safety model of an indirect contact with a low-voltage electric device. This model was used for computations and analyses concerning the following: the probabilities of appearance of the particular shock protection unreliability states, electric shock states (ventricular fibrillation), contributions of the unreliability of different shock protection elements to the probability of occurrence of these states, as well as the risk of electric shock (and the shock safety), and contributions of the intensity of occurrence of damages to different shock protection elements to this risk. An example of a possibility to reduce the risk of an electric shock through changing the intensity of occurrence of damages to the selected protection elements was provided.

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Autorzy i Afiliacje

Włodzimierz Korniluk
Dariusz Sajewicz

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