The article dwells upon the criteria of the equipment condition. The selection of diagnostic methodology and parameters, which not only detects condition but allows to carry out diagnostics with the required operation conditions and maintenance depth. Among the big variety of measured parameters the most informative are acoustic vibrations, which sources are cinematic pair impacts (piston-cylinder, pin-sleeve, etc.)
The sources of vibration acoustic signals of piston machines are given in the article:
Unbalance of the moving and rotating masses – inertial force of reciprocal moving masses, centrifugal force of inertia and the moments of the force.
Gasdynamic processes – pressure force of gases, gas flow during an admission and release.
Impacts and friction between elements and details of assemblies and mechanisms.
The methodology and algorithms of diagnosing of piston machines in real-time monitoring systems are described in the article. Also, the article gives the examples of a proper response of vibroacoustic signals’ various parameters to the condition changes of various piston compressor assemblies.
Kostyukov V.N., Naumenko A.P. Analysis of modern methods and means for piston compressors monitoring and diagnostics. Part 2. Real-time monitoring systems // NDT world. - 2010. - №2. - pp. 28-35
Repair quality in a depot can be influenced by an after-repair control, carried out either by dint of simple tools and devices or within debugging by means of an EMU train testing under a contact wire in several different operating modes. Such approach presupposes substantial time expenditures, which count up to 30 % of the whole processing cycle, and the results are subjective due to different levels of executors’ qualification and responsibilities.
To change dramatically the actual situation and to increase the repair quality of motor driven rolling stock (MDRS) within a simultaneous reduction of an obligatory control duration and labour intensity, one can use automatic systems for comprehensive monitoring.
Well-known developments in the field of railway transport health diagnostics possess a low degree of a unit control procedures automation within diagnostics and diagnosis-making and are focused on a locomotive rolling stock (electric and diesel locomotives), which does not allow to use these developments for EMU-trains electrical circuits diagnostics due to considerable structural and principal differences from MDRS.
The article contains the results of development and industrial application at “Russian Railways” JSC of the comprehensive system for EMU-trains sections diagnostics COMPACS®-EXPRESS-TR3, which provides an off-line automatic reliable and complete MDRS health monitoring in the depot conditions.
Kazarin D.V. Condition monitoring of electrical circuits in commuter trains // World of Transport. - 2010. - № 2. - pp. 60-63
The article considers a scheme, implemented in COMPACS® system for piston compressors real-time health monitoring. There are practical examples of different vibroacoustic signals parameters reaction to changes in the piston compressor units health. Peculiarities and efficiency of monitoring and diagnostic systems implementation have been described as well.
Kostyukov V.N., Naumenko A.P. Contemporary methods and means of piston compressors condition monitoring and diagnostics. Part 2 // Chief Power Engineer. - 2010. - № 12. - pp. 46-54
The article considers state and prospects of contemporary methods and means for piston compressors health monitoring and diagnostics at hazardous continuous production facilities. There is a review of health monitoring principles, implemented in all the known monitoring systems. The equipment health criteria are described as well. The authors have carried out the diagnostic features selection for monitoring purposes and described the vibroacoustic signal sources. Methodology and algorithms of piston compressors diagnostics are also included in the article.
Kostyukov V.N., Naumenko A.P. Contemporary methods and means of piston compressors condition monitoring and diagnostics. Part 1 // Chief Power Engineer. - 2010. - № 11. - pp. 40-50
Monitoring purposes for technical objects are: a timely detection of incipient malfunctions, an observation of their development up to a critical state and a timely personnel warning on malfunctions occurrence in order to develop measures aimed at ensuring a maximal duration of the unit operation and a timely fault-free decommissioning for repair.
The monitoring time interval, starting with preparation for measurements and up to fulfillment of regulations, should be significantly shorter than the malfunctions development interval from the moment of detection to a critical level. Results of the units large-scale monitoring at petrochemical complexes show that the minimal intervals of malfunctions development up to critical levels do not exceed 10-20 minutes, but they can be significantly shorter – up to 3-5 minutes – due to the “human factor” adverse effect. The necessity to prevent accidents caused by such factors has determined emergence of automatic stationary systems for health monitoring of hazardous production facilities units, primarily in petrochemistry, metallurgy and railway transportation.
Thus, the radical difference between monitoring and diagnostics lies in necessity of taking into account the time factor. This gives us the following definition of the unit health monitoring (unit monitoring) - monitoring of the unit technical state (design of machine, unit, mechanism) for determination and prediction of entering the limiting state. Monitoring is diagnostics, expanded in time. The fundamental difference between health monitoring and parameters monitoring is the presence of the measured parameters interpreter in terms of the unit technical state (expert system for decision-making support on the unit health and further control).
Kostyukov V.N. Systems for real-time comprehensive health monitoring of equipment // NEFTEGAZ. - 2010. - pp. 44-45
A structural mathematical description of a vibroacoustic signal, obtained from a piston machine specific units with regard to a channel of vibroacoustic oscillations formation and distribution, is a diagnostic model. This model allows to select informative diagnostic features of malfunctions and defects.
The generalized structural model of the vibroacoustic signal, generated by different sources in the piston machine, is built in the presence and interaction of three main sources of vibro-acoustic oscillations in the unit, which are is identified by oscillations types: free damped, forced undamped, random broadband and narrowband oscillations.
In order to form the diagnosis-making algorithms, based on the vibroacoustic signal parameters and invariant to machines and mechanisms design, it is necessary to develop particular structural models of the vibroacoustic signal for a specific malfunction or defect on the basis of the generalized model.
Naumenko A.P. On some models of vibroacoustic signals structure in piston machines // Engine-2010. - 2010. - pp. 75-78
Fundamental causes of high costs and production losses are: poor observability, difficult controllability and, consequently, low stability of flow processes. The main factors conditioning such a situation are: difficulties in detecting hidden errors of the equipment design, production and mounting, as well as hidden nature of malfunctions occurrence and development, poor observability of the equipment degradation processes, human factor negative influence and, of course, absolutely ineffective system of schedule-based preventive repair, which is unable to root out emergency and unscheduled repairs, and therefore production downtimes and loss of resources.
Observability of the equipment degradation process allows to exclude emergency repairs and carry out all the units repairs according to their actual health in a scheduled manner, thus providing 100% elimination of emergency situations. When speaking about money saving, one should realize that there is not only reduction of material resources consumption, but that of the enterprise labor and financial costs, intended to eliminate the consequences of accidents, breakdowns and shutdowns losses.
The real increase of processing units run-to-repair up to 2-5 years (which is currently required by all of the companies from their plants) is impossible without implementation of health monitoring systems COMPACS® - the basic element of safe money saving production operation.
Kostyukov A.V. COMPACS system - a comprehensive solution for run-to-repair increase of production facilities operation // Modern systems for diagnostics and control of oil-refining and petrochemical equipment (Seminar of Chief Mechanics). - 2010. - p. 70-73
The article considers analysis of existing methods and means for piston compressors monitoring and diagnostics. The peculiarities of the diagnostic and monitoring systems implementation have been presented, the piston compressors main units, which monitoring and diagnostics is of the main focus, have been listed. Architectures and operational principles of the known systems for the piston compressors monitoring and diagnostics have been considered.
Foreign stationary systems for on-line monitoring of the piston compressors parameters exercise control over these parameters, not determining the reasons for their changes, caused by specific malfunctions and their hazard rates.
Real-time systems for the equipment technical state monitoring, proposed and developed in Russia for more than 30 years, are deprived of these drawbacks. The fundamental difference between the real-time monitoring systems and the considered on-line monitoring systems lies in the integrated automated expert system for diagnosis-making, which automatically and in real-time points to the staff the degree of malfunctions development and their danger for the piston compressors and a technological unit, through a "thin" automatic analysis of signals.
Kostyukov V.N., Naumenko A.P. Analysis of modern methods and means for piston compressors monitoring and diagnostics. Part 1. On-line monitoring systems // NDT world. - 2010. - №1. - pp. 64-70
The article considers the method of errors standardless assessment in machines assembling, based on analysis of the vibro-acoustic signals, related to unobservable errors in machines and units, arising within production and operation, some of which do not have an adequate representation in relations and intervals scales.
There has been established a canonical equation of connection between the signal diagnostic features and the machine state structural parameters, represented as ordinal scales; where the equation constitutes the first corner bisectrix of an information plane.
Modeling and experimental research results have been presented.
There has been received an assessment of a diagnostic error, caused by a stochastic communication between diagnostic features and structural parameters, which is inversely proportional to Spearmen's rank-order correlation ratio between them.
The vibro-acoustic method allows to single out during running and acceptance tests the machines with large values of errors and send them back for finishing, preventing their operation.
The proposed approach eliminates the need for training the diagnostic systems on machines-standards with known errors and significantly reduces financial and time costs for the diagnostic systems implementation.
Kostyukov V.N., Kostyukov Al.V. Errors assessment in machines assembling by a vibro-acoustic method // Assembling in mechanical engineering, instrument making. - 2010. - №1. - pp. 22-28
The technological cycle of the large volume current repair (TR-3), carried out in a depot, includes long and labor-consuming operations of removal, dismantling for audit, repair, assemblage, tests, transportation of the equipment and assemblies and their back mounting on an electric multiple unit. At the last stages of this cycle the repaired, tested and operable equipment can be damaged, as well as its working capacity, being a part of the electric multiple unit system, can be disturbed owing to violation of functional interrelations.
Lack of appropriate means and methods for an objective quality control of repair, assemblage and adjustment of responsible and most difficult systems of the electric multiple unit, i.e. first of all electrical circuits, within a limited idle time at the depot does not allow to carry out a high-quality control of the performed works. As a result, “raw” electric multiple units are admitted to an after repair running and besides undebugged (hidden) defects, which percentage reaches from 30 to 40 %, have many new ones, appeared due to a so-called human factor. Duration of a debugging stage, success of acceptance tests and further non-failure operation of an electric multiple unit in this case directly depends on debuggers’ qualification and their other subjective qualities.
It is possible to change radically the current situation on the basis of automatic systems for comprehensive diagnostics - to transfer the debugging stage from under a contact wire to a repair shop with simultaneous reduction of its duration, as well as to provide the quality assessment objectivity for the repair, assemblage and adjustment of the electric multiple unit equipment and systems and, as a result, to increase percentage of zero defects since the first presentation within acceptance tests. Such systems are based on the automated expert system for malfunctions detection, which excludes a diagnostician’s subjective errors and provides a reliable quantitative and qualitative assessment for a technical state of the electric multiple unit most difficult and responsible systems according to the main regulating documents requirements.
Kostyukov V.N., Kostyukov Al.V., Kazarin D.V. Equipment diagnostics in electrical circuits of electric multiple units when debugging and acceptance tests // Control. Diagnostics. - 2010. - №1. - pp. 26-35