scholarly journals Estimation peculiarities of external polymer insulation reliability of gas-filled instrument transformers

2021 ◽  
pp. 3-9
Author(s):  
Liudmyla Zhorniak ◽  
Alexej Afanasiev ◽  
Vitaliy Schus ◽  
Olexij Morozov ◽  
Julia Rudenko
Keyword(s):  
High Voltage ◽  
Accurate Determination ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Operational Reliability ◽  
Current Transformer ◽  
Operating Conditions ◽  
Distribution Law ◽  
Instrument Transformers ◽  
And Performance

In the article, the authors propose a method for estimating the parameters of theoretical distributions for calculating the indicators of operational reliability. In the article, the authors propose a method for estimating the parameters of theoretical distributions for calculating the indicators of the operational reliability of a solid insulating structure of high-voltage devices, which is a supporting insulating cover for high voltage instrument transformers filled with gas as an insulating liquid. This technique makes it possible to estimate the parameters of a new distribution law, which is chosen on the condition that it does not contradict the existing distribution law with its known parameters. The developed technique makes it possible to obtain the values of the indicators of the operational reliability of high-voltage equipment by determining the parameters of theoretical distributions, if the developer is the data of experimental studies or statistical information as a result of monitoring the operation of insulating structures, taking into account the actual operating conditions of such high-voltage devices.  This makes it possible to take into account the influence of external factors and performance characteristics inherent in instrument transformers, both current and voltage. In the proposed methodology, as an example, a supporting insulating casing is considered, which is during operation in the most unfavorable conditions, such as external pollution, humidification, overvoltage, etc. The theoretical conclusions are confirmed by the results of calculations using the example of the design of a current transformer of the ТОГ-362 series. A more accurate determination of the effectiveness of the proposed method for predicting the parameters of theoretical distribution laws can be achieved by performing an additional series of calculations and experimental tests of specific insulating structures. Thus, it was concluded that it is possible to use the results obtained to assess the operational reliability of both gas-filled instrument transformers and similar high-voltage equipment.

Flow Coefficient Evaluation of Poppet Valves Used in Reciprocating Compressors for LDPE

2008 ◽  
Author(s):  
Enzo Giacomelli ◽  
Massimo Schiavone ◽  
Fabio Manfrone ◽  
Andrea Raggi
Keyword(s):  
Pressure Drop ◽  
Time Pressure ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Flow Coefficient ◽  
Operating Life ◽  
High Fatigue ◽  
Strongly Connected ◽  
And Performance ◽  
Poppet Valves

Poppet valves have been used for a long time for very high pressure reciprocating compressors, as for example in the case of Low Density Polyethylene. These applications are very critical because the final pressure can reach 350 MPa and the evaluation of the performance of the machines is strongly connected to the proper operation and performance of the valve itself. The arrangement of cylinders requires generally a certain compactness of valve to withstand high fatigue stresses, but at the same time pressure drop and operating life are very important. In recent years the reliability of the machines has been improving over and over and the customers’ needs are very stringent. Therefore the use of poppet valves has been extended to other cases. In general the mentioned applications are heavy duty services and the simulation of the valves require some coefficients to be used in the differential equations, able to describe the movement of plate/disk or poppet and the flow and related pressure drop through the valves. Such coefficients are often determined in an experimental way in order to have a simulation closer to the real operating conditions. For the flow coefficients it is also possible today to use theoretical programs capable of determining the needed values in a quick and economical way. Some investigations have been carried out to determine the values for certain geometries of poppet valves. The results of the theory have been compared with some experimental tests. The good agreement between the various methods indicates the most suitable procedure to be applied in order to have reliable data. The advantage is evident as the time necessary for the theoretical procedure is faster and less expensive. This is of significant importance at the time of the design and also in case of a need to provide timely technical support for the operating behavior of the valves. Particularly for LDPE, the optimization of all the parameters is strongly necessary. The fatigue stresses of cylinder heads and valve bodies have to match in fact with gas passage turbulence and pressure drop, added to the mechanical behavior of the poppet valve components.

Vibration Based Condition Monitoring of Helicopter Gearboxes Based on Cyclostationary Analysis

2019 ◽  
Author(s):  
Alexandre Mauricio ◽  
Linghao Zhou ◽  
David Mba ◽  
Konstantinos Gryllias
Keyword(s):  
Experimental Tests ◽  
Operational Reliability ◽  
Health Condition ◽  
Operating Conditions ◽  
False Alarms ◽  
Complex Structures ◽  
Planetary Gearbox ◽  
Bearing Defects ◽  
Envelope Spectrum ◽  
Selection Of

Abstract The core of a helicopter drivetrain is a complex planetary main gearbox (MGB) which reduces the high input speed generated by the engines in order to provide the appropriate torque to the main rotors and to other auxiliary systems. The gearbox consists of various shafts, planetary gears and bearings and operates under varying conditions under excessive friction, heat and high mechanical forces. The components are vulnerable to fatigue defects and therefore Health and Usage Monitoring Systems (HUMS) have been developed in order to monitor the health condition of the gearbox, focusing towards early, accurate and on time fault detection with limited false alarms and missed detections. The main aim of a HUM System is by health monitoring to enhance the helicopters’ operational reliability, to support the maintenance decision making, and to reduce the overall maintenance costs. The importance and the need for more advanced and accurate HUMS have been emphasized recently by the post-accident analysis of the helicopter LN-OJF, which crashed in Norway in 2016. During the last few decades various methodologies and diagnostic indicators/features have been proposed for the monitoring of rotating machinery operating under steady conditions but still there is no global solution for complex structures. A new tool called IESFOgram has been recently proposed by the authors, based on Cyclostationary Analysis, focusing on the accurate selection of a filtering band, under steady and varying speed conditions. Moreover the Cyclic Spectral Coherence is integrated along the selected frequency band leading to an Improved Envelope Spectrum. In this paper the performance of the tool is tested on a complex planetary gearbox, with several vibration sources. The method is tested, evaluated and compared to state of the art methods on a dataset captured during experimental tests under various operating conditions on a Category A Super Puma SA330 main planetary gearbox, presenting seeded bearing defects of different sizes.

scholarly journals RESEARCH OF TECHNICAL CHARACTERISTICS OF NEW TYPES OF COUPLINGS

2020 ◽  
pp. 113-121
Author(s):  
Oleksii Tokarchuk ◽  
Yurii Polievoda
Keyword(s):  
Elastic Element ◽  
Rational Design ◽  
Experimental Studies ◽  
Bending Moment ◽  
Operational Reliability ◽  
Modern Technology ◽  
Operating Conditions ◽  
The Moment ◽  
Working Bodies ◽  
Moment Of Resistance

Dynamic loads that occur during the operation of existing couplings cause significant shock loads, which leads to rapid wear of the surfaces of the couplings and shortens the service life. Modern technology faces the task of improving the operational reliability of the working bodies and drives of machines. One way to solve this problem is to develop and use high-precision and low-dynamic safety couplings. In this regard, the question of developing new designs of safety couplings that reduce impact loads and increase the reliability and durability of machinery is relevant. The synthesis of structural and kinematic schemes of ball, cam and planetary safety couplings, the method of their calculation in combination with the nature of the change in the moment of resistance on the working body of the equipment. The article conducts a set of theoretical and experimental studies to determine their rational design, kinematic and dynamic parameters that will satisfy the operating conditions of machines and mechanisms. A force analysis of the elastic element (ring spring) was performed. The scheme of loading of an elastic element by two forces and other settlement schemes are constructed, namely: equivalent system; force diagrams for determining the load torque; force schemes for determining the unit moment; schemes of total bending moment; force schemes to determine the total unit moment. During static experimental studies of the developed ball safety couplings, the nature of their operation was established, the maximum torque at the two stages of operation of the couplings was determined and a comparative analysis between the results of theoretical and experimental studies was performed. The positive results of experimental researches of the developed coupling and theoretical positions which can be applied to a substantiation and a choice of rational parameters of the developed designs of couplings and their engineering designing were confirmed.

scholarly journals Temperature, Ageing and Thermal Management of Lithium-Ion Batteries

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1248
Author(s):  
Lena Spitthoff ◽  
Paul R. Shearing ◽  
Odne Stokke Burheim
Keyword(s):  
Lithium Ion Batteries ◽  
Thermal Management ◽  
Critical Role ◽  
Experimental Studies ◽  
Lithium Ion ◽  
High Energy ◽  
Operating Conditions ◽  
Battery Lifetime ◽  
Temperature Ageing ◽  
And Performance

Heat generation and therefore thermal transport plays a critical role in ensuring performance, ageing and safety for lithium-ion batteries (LIB). Increased battery temperature is the most important ageing accelerator. Understanding and managing temperature and ageing for batteries in operation is thus a multiscale challenge, ranging from the micro/nanoscale within the single material layers to large, integrated LIB packs. This paper includes an extended literature survey of experimental studies on commercial cells investigating the capacity and performance degradation of LIB. It compares the degradation behavior in terms of the influence of operating conditions for different chemistries and cell sizes. A simple thermal model for linking some of these parameters together is presented as well. While the temperature appears to have a large impact on ageing acceleration above room temperature during cycling for all studied cells, the effect of SOC and C rate appear to be rather cell dependent.Through the application of new simulations, it is shown that during cell testing, the actual cell temperature can deviate severely from the reported temperature depending on the thermal management during testing and C rate. It is shown, that the battery lifetime reduction at high C rates can be for large parts due to an increase in temperature especially for high energy cells and poor cooling during cycling studies. Measuring and reporting the actual battery (surface) temperature allow for a proper interpretation of results and transferring results from laboratory experiments to real applications.

scholarly journals Experimental studies of the thermal management system for an electric vehicle in the X-In-The-Loop environment

2021 ◽  
Vol 2061 (1) ◽  
pp. 012120
Author(s):  
R H Kurmaev ◽  
A A Umnitsyn
Keyword(s):  
Electric Vehicle ◽  
Thermal Management ◽  
High Voltage ◽  
Management System ◽  
Experimental Studies ◽  
Point Of View ◽  
Operating Conditions ◽  
Traction Drive ◽  
Thermal Management System ◽  
The Cost

Abstract This article presents the experience of conducting experimental studies of the thermal management system (TMS) intended for the traction electric drive of an electric vehicle, which has each of its wheels driven by an in-wheel motor, in the X-In-the-Loop environment. The paper describes the experimental bench of the thermal management system, which makes it possible to simulate the operating conditions of the high-voltage components of the traction drive of an electric vehicle from the point of view of thermal-hydraulic characteristics. A brief description of the mathematical model used in real-time calculations during both local and collaborative experimental studies is given. The process of collaborative testing of the TMS of high-voltage components of the traction drive of an electric vehicle, in the X-In-the-Loop environment, as well as the results, is demonstrated. A similar approach used in the development of TMS allows increasing the efficiency of the system developed, by optimizing the control algorithm for the executive devices of the TMS, reducing the weight, as well as the overall dimensions of the components, and conducting a detailed analysis of each component. It is also worth noting that the use of collaborative experimental research in the X-In-the-Loop environment will reduce the cost of the experiment, as well as, ultimately, the cost of the product, since with such an approach there is no need for a real test object for each company engaged in the development of one or another electric.

scholarly journals Smart Characterization of Rogowski Coils by Using a Synthetized Signal

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3359 ◽  
Author(s):  
Alessandro Mingotti ◽  
Lorenzo Peretto ◽  
Roberto Tinarelli
Keyword(s):  
Low Power ◽  
Distribution System ◽  
Network Models ◽  
Experimental Tests ◽  
Current Transformer ◽  
Rogowski Coil ◽  
Sufficient Information ◽  
Instrument Transformers ◽  
Rogowski Coils ◽  
Characterization Procedure

With the spread of new Low-Power Instrument Transformers (LPITs), it is fundamental to provide models and characterization procedures to estimate and even predict the LPITs’ behavior. In fact, distribution system operators and designers of network models are looking for all forms of information which may help the management and the control of power networks. For this purpose, the paper wants to contribute to the scientific community presenting a smart characterization procedure which easily provides sufficient information to predict the output signal of a Low-Power Current Transformer (LPCT), the Rogowski coil. The presented procedure is based on a synthetized signal applied to the Rogowski coil. Afterwards, the validity of the procedure is assessed within the Matlab environment and then by applying it on three off-the-shelf Rogowski coils. Simulations and experimental tests and results involving a variety of distorted signals in the power quality frequency range and by adopting a quite simple measurement setup demonstrated the effectiveness and the capability of the procedure to correctly estimate the output of the tested device.

scholarly journals Experimental Investigation of Stall and Surge in a Multistage Compressor

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Enrico Munari ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Pier Ruggero Spina ◽  
Alessio Suman
Keyword(s):  
Mass Flow ◽  
Flow Instability ◽  
Numerical Models ◽  
Characteristic Curve ◽  
Experimental Studies ◽  
Operational Reliability ◽  
Operating Conditions ◽  
Test Facility ◽  
Extensive Literature ◽  
Test Rig

Flow instability conditions, in particular during surge and stall phenomena, have always influenced the operational reliability of turbocompressors and have attracted significant interest resulting in extensive literature. Nowadays, this subject is still one of the most investigated because of its high relevance on centrifugal and axial compressor operating flow range, performance, and efficiency. Many researchers approach this important issue by developing numerical models, whereas others approach it through experimental studies specifically carried out in order to better comprehend this phenomenon. The aim of this paper is to experimentally analyze the stable and unstable operating conditions of an aeronautic turboshaft gas turbine axial–centrifugal compressor installed on a brand new test rig properly designed for this purpose. The test facility is set up in order to obtain (i) the compressor performance maps at rotational speeds up to 25,000 rpm and (ii) the compressor transient behavior during surge. By using two different test rig layouts, instabilities occurring in the compressor, beyond the peak of the characteristic curve, are identified and investigated. These two types of analysis are carried out, thanks to pressure, temperature, and mass flow sensors located in strategic positions along the circuit. These measurement sensors are part of a proper control and acquisition system, characterized by an adjustable sampling frequency. Thus, the desired operating conditions of the compressor in terms of mass flow and rotational speed and transient of these two parameters are regulated by this dedicated control system.

scholarly journals Vibration-Based Condition Monitoring of Helicopter Gearboxes Based on Cyclostationary Analysis

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Alexandre Mauricio ◽  
Linghao Zhou ◽  
David Mba ◽  
Konstantinos Gryllias
Keyword(s):  
Experimental Tests ◽  
Operational Reliability ◽  
Health Condition ◽  
Operating Conditions ◽  
False Alarms ◽  
Planetary Gearbox ◽  
Bearing Defects ◽  
Feature Optimization ◽  
Envelope Spectrum ◽  
Selection Of

Abstract The core of a helicopter drivetrain is a complex planetary main gearbox (MGB), which reduces the high input speed generated by the engines in order to provide the appropriate torque to the main rotors and to other auxiliary systems. The gearbox consists of various shafts, planetary gears, and bearings, and operates under varying conditions under excessive friction, heat, and high mechanical forces. The components are vulnerable to fatigue defects and therefore health and usage monitoring systems (HUMS) have been developed in order to monitor the health condition of the gearbox, focusing toward early, accurate, and on-time fault detection with limited false alarms and missed detections. The main aim of a HUMS is by health monitoring to enhance the helicopters' operational reliability, to support the maintenance decision-making, and to reduce the overall maintenance costs. The importance and the need for more advanced and accurate HUMS have been emphasized recently by the postaccident analysis of the helicopter LN-OJF, which crashed in Norway in 2016. During the last few decades, various methodologies and diagnostic indicators/features have been proposed for the monitoring of rotating machinery operating under steady conditions but still there is no global solution for complex structures. A new tool called improved envelope spectrum via feature optimization-gram (IESFOgram) has been recently proposed by the authors, based on cyclostationary analysis, focusing on the accurate selection of a filtering band, under steady and varying speed conditions. Moreover, the cyclic spectral coherence (CSCoh) is integrated along the selected frequency band leading to an improved envelope spectrum (IES). In this paper, the performance of the tool is tested on a complex planetary gearbox, with several vibration sources. The method is tested, evaluated, and compared to state-of-the-art methods on a dataset captured during experimental tests under various operating conditions on a Category A Super Puma SA330 main planetary gearbox, presenting seeded bearing defects of different sizes.

scholarly journals Technological features of production of copper-based composites reinforced with cast iron granules by means of casting

2019 ◽  
pp. 114-118
Author(s):  
A. S. Kalinichenko ◽  
V. A. Sheinert ◽  
V. A. Kalinichenko ◽  
A. G. Slutsky
Keyword(s):  
Cast Iron ◽  
Composite Materials ◽  
Low Cost ◽  
Experimental Studies ◽  
Operational Reliability ◽  
Operating Conditions ◽  
High Wear Resistance ◽  
Friction Units ◽  
Wide Range ◽  
Methods Of Synthesis

Increasing the operational reliability of friction units is one of the priorities for mechanical engineering, which requires the creation of effective tribotechnical materials. First of all, this applies to sliding bearings, which are used in various friction units in a wide range of operating conditions and must meet a number of requirements: low coefficient of friction, high wear resistance and fatigue resistance, as well as good thermal conductivity, workability, corrosion resistance and machinability, low coefficient of linear expansion and low cost. It is problematic to satisfy these requirements in real conditions; therefore, different friction materials that are best suited to specific conditions have been developed. In particular, cast composite materials (LCM) have been developed, which have found application in various friction units operating in severe operating conditions. Currently, the theoretical foundations of the mechanics of reinforced composite materials are well developed, and a significant progress has been achieved in their material science. However, there are still many problems associated with the choice of optimal technology ensuring the achievement in practice of the predicted composites properties by theory, control of interfacial interaction to improve the stability of the structure and properties of CM, with the development of new types of reinforcing elements that can raise the level of composite performance.In the present work results of scientific and experimental studies on the development of casting technology (solid-liquid synthesis) for obtaining composite materials with macroheterogeneous structure have been summarized. The structures of composites are studied for different methods of synthesis, as well as for different chemical composition of cast iron granules. The prospects of using white vanadium cast iron granules as a reinforcing phase are shown.

scholarly journals Influence of Contact Plateaus Characteristics Formed on the Surface of Brake Friction Materials in Braking Performance through Experimental Tests

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4931
Author(s):  
Rafael Lucas Machado Pinto ◽  
Juan Carlos Horta Gutiérrez ◽  
Robson Bruno Dutra Pereira ◽  
Paulo Eustáquio de Faria ◽  
Juan Carlos Campos Rubio
Keyword(s):  
Friction Pair ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Performance Measurements ◽  
Friction Materials ◽  
Braking Performance ◽  
Emergency Braking ◽  
The Coefficient Of Friction ◽  
And Performance

This work applies a procedure for analysis and characterization of the surface of brake friction materials, correlating them with the tribological and thermal properties achieved in different vehicle braking conditions. Experiments were performed in a vehicle under two real conditions of braking operation, simulated flat track descent and emergency braking. Characteristics of the plates formed on the surfaces of the friction materials were analyzed by scanning electron microscopy (SEM) and correlated with the performance during braking, as measured by the coefficient of friction at the interface of the friction pair and temperature. As a result, the formation of the primary and secondary plateaus in these two different braking operating conditions was observed, and the relationship between the characteristics of the plateaus formed on the surface and the surface roughness parameters and performance measurements during braking.

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