In the process of railway rolling stock operation the most crucial units, subjected to sudden failures, are critical for the whole rolling stock. These primarily include electrical and mechanical units, where troubleshooting within operational process is rather difficult.
The most effective methods of defects detection in rotary mechanical equipment are thermal and vibroacoustic ones, however the thermal method allows only to establish the fact of the unit destruction, or detect defects at a late stage of their development, while the vibroacoustic method of non-destructive testing allows to detect both incipient and developed defects.
A large number of noise components, accompanied with interaction between a wheel and a track, has lead to a conclusion that an objective vibroacoustic health monitoring within operational process of the rolling stock rotary mechanical parts is rather difficult and sometimes is even impossible.
Meanwhile, to achieve a dynamic error equal to 1% (an acceptable level for critical equipment is 0.1%) it is necessary to carry out diagnostics at intervals of not more than 2 hours, which can realized only through implementation and application of on-board health monitoring systems.
The research purpose is to determine the most informative, from vibration analysis point of view, frequency range of a vibration signal for an expert system development and the railway rolling stock condition monitoring.
Primary analysis of data has proved that vibration parameters level on a traction motor differs significantly from vibration parameters levels on other electric motors, installed on the same car. This fact has allowed to presume the traction motor malfunction.
The analysis has shown that the vibration parameters level in different frequency bands is substantially influenced by the rolling stock running speed and operating modes. It has been also established that units with different state of health are influenced in a different manner.
Discrete components of vibration acceleration envelope spectrum, corresponding to frequencies of these or those defects occurrence, are revealed in different speed modes that should be used in the expert system development.
As a result, characteristics of vibration parameters distribution in the rolling stock units within an electric multiple unit train motion in different frequency bands and speed modes have been determined, as well as impacts effect generated from variable speed and dynamic operating modes.
The research results are intended for application within development of the expert system, implemented in on-board systems for the rolling stock units condition monitoring.
Kostyukov Al.V., Tsurpal A.E., Basakin V.V. Research of vibration in railway rolling stock mechanical parts // Condition Monitoring and Machinery Failure Prevention Technologies (СМ/MFPT 2014)
The carried out studies, as well as technical analysis of defects, malfunctions and unscheduled repair of electric trains revealed that in the system of the train’s auxiliary DC circuits that most liable to failures element is an electric auxiliary converter.
The paper describes a technology of diagnosing an electric train’s DC converter using three-phase alternating current spectrum parameters.
The examples of a three-phase alternating current spectrum of a faultless converter, and a converter in a pre-accident condition are given.
Kazarin D.V., Tsurpal A.E., Ilyushin M.S. Diagnostics of electric auxiliary converter of a direct current electric train using parameters of three-phase alternating current spectrum // Dinamika sistem, mehanizmov i mashin (Dynamics of systems, mechanisms and machines). - Omsk: OmSTU, 2014. - Iss. 4. - p. 119-121
To increase diagnostic reliability providing an objective assessment of equipment’s condition is an urgent task. The paper includes the estimation of errors for wheel-motor unit axle equipment diagnostics carried out while testing wheel-pairs at various rotation frequencies.
The main diagnostic task is to recognize condition of assemblies and machines and classify them as faultless or faulty, which is related to risks of false alarm or defect skipping. Utilization of any of the diagnostic methods may lead to such errors as defect skipping or false alarm.
A defect skipped during a rolling stock operation may lead to the destruction of an assembly, and that may cause not only an expensive unscheduled repair, failures in train movement schedule, but also a hazard or an accident. False alarm may lead to additional repairs at the assemblies that do not require any maintenance, which can make the condition even worse, thus, reducing the operational readiness of the rolling stock.
The paper is aimed at increasing reliability of diagnostics with minimum costs of testing.
Zaytsev A.V., Teterin A.O. Method applied for increasing reliability of diagnostics of axle equipment of wheel-motor units in electric trains // Dinamika sistem, mehanizmov i mashin (Dynamics of systems, mechanisms and machines). - Omsk: OmSTU, 2014. - Iss. 4. - p. 115-118
To improve the existing methods of operation-based condition diagnostics of rolling bearings is an urgent task.
The most efficient method for detection of both nucleating and developed defects of rolling bearings is the vibration-acoustic method of non-destructive testing. Operation of rolling bearings is closely related to changes in wide range of both rotation frequencies and radial/axial loads. To provide an adequate assessment of rolling bearings condition using vibration-acoustic method one needs to know what impact various factors have on vibration rates.
The paper considers a method of conducting an experimental study, as well as an experimental stand evaluating the dependency between rolling bearing parameters and rotation frequencies, radial/axial loads.
Basakin V.V., Kudryavtseva I.S., Zaytsev A.V., Teterin A.O. Method of experimental research on bearing vibration // Dinamika sistem, mehanizmov i mashin (Dynamics of systems, mechanisms and machines). - Omsk: OmSTU, 2014. - Iss. 4. - p. 112-115
The paper dwells upon the basic concepts of choosing condition monitoring system for pump and compressor units of refinery production of various categories of hazard (according to GOST R 53563-2009), increasing units’ run-to-failure time and accident-free resource-saving operation.
The paper describes basic principles of monitoring and real-time diagnostics systems building, specifications of the system’s software and hardware based on selection and rationalization of classification factors according to GOST R 53564-2009. The correlation between failure skipping risk and system’s class is shown.
The main goal of equipping hazardous production facilities with a comprehensive monitoring system is to ensure safe resource-saving operation of machinery by means of preliminary control actions providing necessary stability margin, high-quality rates of its functioning and technological, ecological and economical safety.
Kostyukov V.N., Naumenko A.P., Tkachenko A.A. Concept of selection and rationalization of pumps condition monitoring system specifications // Increasing pump units’ reliability. Analysis of existing pump systems. Basic concepts of design and choice of pump units for refinery and petrochemical companies: from the expert meeting. – Moscow: Council of Chief Mechanical Engineers, 2014. - p. 81-101.
Main source of continuous production enterprise’s profitability comes from decreasing operational costs and losses due to accidents and production downtime caused by sudden breakdown of machinery units. Reliability analysis of oil and petrochemical companies shows that more than three forth of equipment failures are failures of machines and mechanisms, which often leads to accidents and production defects, downtime of production facilities and units. About 80% of mechanical equipment at refinery production today, are pumps and compressors. That is why condition of production facilities mostly depends on the condition of their pumps and compressors.
The solution for low-objective assessment of machinery condition in actual operation is condition monitoring with automatic expert systems providing decision-making on the basis of the machinery condition and repair time. Such an expert sub-system is an integral part of the COMPACS® automated control systems for safe resource-saving operation of machinery. The systems are implemented at dozens of oil and petrochemical companies of Russia.
The article describes methodical basis for providing safe operation of pumps and compressors at hazardous productions, an example of practical application of vibration-acoustic method of condition assessment and signal spectral analysis for machinery parts deterioration and early development of hydroshok.
Kostyukov V.N., Naumenko A.P., Boychenko S.N. Increasing reliability of pump and compressor units based on monitoring of failures and operation risks // Nasosyi i oborudovanie (Pumps and equipment). - 2014. №4-5, p.28-31.
The article is devoted to real-time monitoring of the equipment failure omission risk using data from computer systems for accidents prevention and machinery condition monitoring COMPACS®. To prove availability of connection between the equipment operating time in different states and the consequences that arise from adverse events, the necessity to determine such events and specify their consequences, as well as to calculate their occurrence frequency depending on operating time, has been shown.
The article includes assessment of possible and probable failures consequences for the units being operated in on unacceptable technical state according to results of the monitoring systems implementation.
The authors have concluded that the automatic calculation and real-time monitoring of the units failure omission risk of hazardous production facilities can be performed only by stationary systems for the equipment health monitoring and presented to all the refinery management levels. This allows the management not only to assume but to know exactly the existing risk level, which is conditioned by the prevailing housekeeping, as well as to make decisions aimed at risk decrease, i.e. to provide the most effective strategy of risk management.
The article describes the examples of the COMPACS® vibration monitoring system application for accident prevention of Reftinskaya GRES equipment: air-blowers, hot-blast fans, smoke exhausters, booster pumps, etc.
Equipping supplementary machinery with the COMPACS® condition monitoring stationary system eliminates accidents and converts “sudden failures” into “gradual” and “observable” and “controllable” by providing expert messages shown on the display covering all problems in diagnosed machinery. Due to that, machinery is ensured to be decommissioned for repair once it utilizes its full resource (reaching “Actions required” or “Unacceptable” condition) with full reparability. Automatic diagnostics provides after-repair commissioning of the machinery with objectively evaluated condition and ensured high quality of repair in “Acceptable” condition.
Application of a condition monitoring system allows to determine the causes of failure nucleation and development, as well as to find the fundamental causes of failures and help personnel to take precise actions for ensuring long-time accident-free operation of machinery.
Diagnostics of cavitation mode plays an important part in safe unit centrifugal pump operation, as soon as cavitation presupposes massive destruction of rotor wheel surface and pipe-lines, and additional vibration loads on unit construction. Currently, the main method of pump unit cavitation mode monitoring is spectral component analysis of case vibration signal. However, spectrum analysis requires precise data on pump unit construction (number of blades on rotor wheel, bearing types). Lack of such data or its irrelevance to the real one will lead to errors in cavitation mode measurements. Consequently, still, one of the urgent problems is development of new cavitation diagnostics methods using algorithms invariant to construction type of the unit.
The article dwells upon cavitation diagnostics of pump units by means of modern non-linear dynamics trend - fractal theory in which Hearst index related to a vibration signal dimension is used as a diagnostic feature. The main advantage of this feature is its invariance to the signal level and, consequently an independence from power and size characteristics of the unit.
The results of Hearst index usage during processes of pump unit testing and operation are also given in the article. It is shown that sensitivity of the feature equals or, in some cases, exceeded sensitivity of a spectral method.
Consequently, Hearst index allows to increase reliability rates of results issued by expert system of centrifugal pump unit health diagnostic system.
References:
Kostyukov V.N. Production safety monitoring. Moscow: Mashinostroyeniye. 2002. 224 p.
Kostyukov V.N., Boychenko S.N., Kostyukov A.V. Automated systems for control of safe money-saving operation of oil-refinery and petrochemical productions (SMSRTM COMPACS®) [edited by. Kostyukov V.N.]. Moscow: Mashinostroyeniye. 1999. 163 p.
Kostyukov V.N. Synthesis of invariant diagnostic features and models of unit condition for diagnostic purposes// Omsk scientific bulletin 2000. Issue 12. p. 77-81.
Mandelbrot B.B. Fractals and chaos. Mandelbrot's set and other miracles. Moscow – Izhevsk: Research Center "Regulyarnaya i haoticheskaya dinamika" 2009. 392 p.
Feder E. Fractals – Moscow: Mir, 1991. 254 p.
Kostyukov V.N., Boychenko S.N. Real-time diagnostics and monitoring of pump unit cavitation mode // Condition Monitoring and Machinery Failure Prevention Technologies (СМ/MFPT 2014)
The authors assess the existing system of operation and maintenance of railway rolling stock in Russia; identify its main disadvantages and challenges. They argue that it is crucial to organize reliable condition monitoring of the most critical equipment.
Following the description of the features of transverter of electric train, they suggest a method of its troubleshooting which is based on monitoring of parameters of spectrum of three-phase alternating current. The method refers to both operational and pre-accident conditions of devices. Adequacy of the procedure is tested and confirmed on the basis of data obtained during the operation of the experimental unit.
Kostyukov V.N., Tsurpal A.E. Troubleshooting of transverter of electric train under operation conditions // Mir transporta. - 2014. - №4. - pp.46-53
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