Synthesis of diagnostic features, appropriate to the piston machines technical condition types, main failures and operation modes, arising both separately and simultaneously, and invariant to the machine construction - is an important issue. One step for this problem solution is to create the diagnostic signal model for the unit under test.
The most common model of the known is a batch action generalized model of a quasi-periodic vibroacoustic signal, proposed by V.N. Kostyukov.
This model shows that the frequency content of the low-frequency vibration spectrum and the vibroacoustic signal envelope, obtained by filtering in the high-frequency field and subsequent detection, are approximately equal. These spectra can be represented by an expansion in the characteristic frequencies, which can be divided into three groups. To evaluate the unit technical condition it is necessary to select and measure the components energy characteristics for each group.
This model describes large classes of the units under test failures. The model further development is the model, which describes the vibroacoustic signals with respect to their sources interaction, thus increasing the diagnosing accuracy and depth, but its use for developing the diagnostic algorithms is not obvious.
Therefore, it is advisable to consider a few examples of the vibroacoustic signal models when specific defects and failures occur, thus forming the piston compressors diagnostic features.
Naumenko A.P. Vibroacoustic model of the piston compressor diagnostic signal // Dynamics of systems, mechanisms and machines. - 2009. - pp. 39-44
The necessary completeness and depth of electric circuits diagnostics can be provided by means of resistance assessment of control circuits loops under consideration and high-voltage power and auxiliary circuits sections. Obviously, the current sensors mounting at each loop of control circuits is inexpedient, as in that case the diagnostic complex complication exceeds the diagnosed object complication in several times.
To determine the specified parameters with the minimal number of sensors and the diagnostic complex flow lines, a principle of control circuits functional-test diagnostics has been developed. The principle consists in determining of each branch diagnostic features through timely inclusion of the branch in the operational process. This inclusion is carried out by means of test impacts injection to the main and auxiliary inputs. The specific sequence of impacts makes them identical to working ones.
At the same time the high-voltage circuits switching units fulfill the assigned functions in the whole range of possible combinations. The use of additional inputs (impacts injection has not been foreseen by the operation working algorithm for these impacts) for test impacts injection even with functional impairment in the branches of control circuits, corresponding to the main inputs, allows to ensure the impact transfer to the actuator, thus performing their primary function.
Kostyukov Al.V., Kazarin D.V. The choice of diagnostic features for electric trains circuits // Nauka, obrazovanie, biznes (Science, education, business). - 2009. - pp. 189-194
Diagnostics of the rolling stock wheel-motor units is an urgent matter of today. Bearing assemblies of wheel-sets and wheel-motor units (WMUs) undergo enormous impact forces and their technical condition largely influences a train performance safety.
It is customary to use 6 vibration sensors which are mounted on the general bearing assemblies (axle bearings, reducer, traction motor). Nevertheless there is an opinion that such a number of sensors is abundant and only increases diagnostic operations time.
In order to determine capability of vibration sensors number reduction while diagnosing of an electric train wheel-motor units, studies on the mutual impact between different subjects diagnostic features have been carried out.
Zaycev А.V., Lagaev А.А., Kostyukov V.N. Capability determination of vibration sensors number reduction while diagnosing of an electric train wheel-motor units // Nauka, obrazovanie, biznes (Science, education, business). - 2009. - pp. 154-157
Operating safety level of units with piston compressors is determined by reliability of their technical condition monitoring, timeliness and accuracy of malfunctions and their causes detection. Nowadays there are numerous technical tools designed for piston compressors monitoring and diagnostics, which are developed and manufactured in different countries by various companies. However, it remains a pending issue if the measurements are adequate to the actual technical condition of piston compressors and to the risk magnitude of their safe operation. Although there is a document that defines the general requirements for critical industrial facilities monitoring systems, nevertheless even experts find it rather difficult to sort out the advertised systems capabilities. In this connection there is an urgent necessity to systematize the condition diagnosing and monitoring methods and means for piston compressors.
Almost all monitoring and diagnostic systems are characterized by:
determination methodology for technical condition of piston compressors units and components is based on measurement of direct structural and technological parameters (relative displacement, pressure, temperature) and implements an online technology;
expert systems use the values of direct structural and technological parameters;
parameters of indirect processes (vibroacoustic oscillations) are used to assess these parameters values without a diagnosis-making and detection of malfunctions and defects causes.
In the equipment vibration analysis system COMPACS® the methodology for real-time monitoring and diagnostics is based not only on the measurement of direct structural and technological parameters, but on the use of vibroacoustic oscillation parameters as well, there have been implemented algorithms of the expert decision support system with an autodetection (in the rate of diagnostic signals measurement) of more than 20 units malfunctions and defects and the degree of their danger.
Naumenko A.P. Analysis of modern methods and means of piston compressors condition monitoring and diagnostics // Nauka, obrazovanie, biznes (Science, education, business). - 2009. - pp. 107-115
The report presents a classification of faults in electrical circuits of trains at their place of origin and distribution of faults on the elements of electrical circuits. The most informative parameters which are useful to measure and record during electrical circuits diagnostics are presented in the report; as well as requirements to the diagnostic system to maintain the relationship and measure the most informative parameters.
Diagnostic system of electrical circuit of motor driven rolling stock can detect the following defects in electrical circuits:
break of train and section control wire;
sticking and malfunction of contacts and power contactors;
nominal deviation of electrical parameters of apparatus, coils and resistors;
break and turn-to-turn short circuit in the elements;
wire fault to frame, as well as wiring errors;
deviation of the time parameters of apparatus due to incorrect regulation, excessive wear or drive scoring;
sequence fault of apparatus operations, etc.
The developed diagnostic system of electrical circuit of train electric units, implemented in a number of motor train depot of the country, provides an objective monitoring of the technical state of apparatus and components of electrical circuits, while reducing labor intensity and span time on troubleshooting and repair.
Kostyukov Al.V., Kazarin D.V. Diagnostic system of electrical circuit of motor driven rolling stock // Nauka, obrazovanie, biznes (Science, education, business). - 2009. - pp. 151-157
Concerning the report we can make the following conclusions:
The use of parameters of oscillatory processes of vehicles and machinery produced by the piezoelectric transducers allows to highlight the section of technical diagnostics, studying and establishing the signs of defects and malfunctions of technical objects, as well as methods and means of detection and search (specify location) of defects and faults on the basis of the analysis of parameters of vibroacoustic signals. This section is called vibroacoustic diagnostics.
Acceleration and displacement of vibroacoustic oscillations determine the internal stresses in structural elements of the object that is the basis for calculating the strength of structural elements, based on the comparison of force appeared in the elements under mechanical loading with the force which transfer the elements into a limit state.
Even at high correlations of "signal/noise" (40 dB) vibroacoustic signals with sinusoidal components can be considered practically independent of their derivatives and integral transforms. Independence of the main parameters of vibroacoustic signals determines their orthogonality to the tasks of vibroacoustic diagnostics.
Vibration displacement should be measured within low frequency of vibroacoustic oscillations, which largely characterizes internal stress and hardness of object clamps.
Vibration velocity should be measured within medium frequency of vibroacoustic oscillations, which characterizes the energy of the vibrational processes that cause deformations and stress of structural elements.
Vibration acceleration should be measured within high and ultrahigh frequency, which will characterize the internal stress in the elements and housing units of the object.
Submission of vibroacoustic oscillations as the result of a superposition of force interactions and their nonlinear interaction determine the use of nonlinear mechanisms of vibroacoustic signals, in particular, the use of the envelope of vibroacoustic signals.
Naumenko A.P. Concerning the choice of vibration analysis parameters // Nauka, obrazovanie, biznes (Science, education, business). - 2008. - pp. 106-115
In the process of production management in the coal mining industry two main problems are solved: process management and equipment performance management. Process management should be stable, it depends not only on the proper work of the operators, but also on the equipment condition, as instability of process management turns into a big financial losses and can lead to accidents and manmade disasters. It`s necessary to sate that the majority of units and equipment are absolutely worn out, and are above standard operation time. Therefore, safe resource-saving operation together with the observability and controllability of the equipment state is a task of the prime importance of the company's management.
Automated Control Systems of Safe Resource-saving operation and Maintenance of equipment ACS SRSM™ COMPACS®, which combined comprehensive monitoring system on processing plants and stationary systems for quality diagnostic of bought equipment and equipment after the repair in a single diagnostic network Compacs-Net®, provide management an objective information about the equipment state in real time. ACS SMSPM™ COMPACS® implement safe resource-saving SM™ - Technology of equipment management (Safe Maintenance) and represent MES system (Manufacturing Execution System) which provides the observability of condition of manufactured, repaired and maintained equipment, control of its quality at all stages of the life cycle, as well as stability, safety and efficiency of production.
Kostyukov V.N., Sinitsyn A.A. Stationary and stand systems for computer monitoring COMPACS for operation quality control and maintenance of equipment // Modern technologies of increasing the efficiency of the coal and mining enterprises. - 2008. - pp. 49-59
Practical implementation of condition monitoring systems of piston machines and piston-type compressors of petrochemical complex requires the creation of state-of-the-art firmware, as well as meets the requirements for the safe operation of the monitoring systems in explosive areas. Therefore, the development of firmware for monitoring systems of piston machines of petrochemical complex covering requirements of the minimum cost strategy of the systems, and ensuring the creation of automated control systems for the safe operation of resource across the enterprise, is problem number one at present.
The present level of development of information-measuring technique makes it possible to organize the collection and processing of data both synchronously and asynchronously on multiple channels with reference to the angle of shaft rotation in a given range of frequencies - from shares and units of hertz to several megahertz. Given that the rate of failure is limited, based on the appropriate period of measuring channels survey, the use of series-parallel distributed data structure is the most appropriate for condition monitoring of centrifugal and piston-type compressors. In recent years, automatic monitoring system of refineries and petrochemical complexes COMPACS® are widespread, meeting all the requirements, implementing the strategy of minimum cost of diagnostic and monitoring system and ensuring the creation of automated monitoring systems of safe operation of resource across the enterprise.
Kostyukov V.N., Naumenko A.P. Software and hardware for the diagnosis and condition monitoring of piston machines // Non-destructive testing and technical diagnostics in industry. - 2008. - pp. 142-145
Nowadays the problem of trouble-free, safe, observable operation of the reciprocator fleet (especially internal combustion engines and reciprocating compressors of oil-and-gas refining, chemical complexes) becomes urgent. In addition, that is a problem of the maximum resource exploitation solvable by development and implementation of the technology for diagnostics and monitoring of the reciprocator technical condition.
The result of technical diagnostics is the determination of values of structural parameters characterizing technical condition of the reciprocator, its units and parts. In order to estimate residual life in terms of the law of variation of controlled parameter during operation it is necessary to know its actual and limiting value. However, determination of actual value of many structural parameters is practically impossible in view of working reciprocator. Their determination during the reciprocator dismantling affects quality of the couplings of re-assembled reciprocator and changes the patterns of processes of interaction of parts in the couplings, which makes practical use of this method of data obtaining unacceptable. In this case, the diagnosing is carried out through indirect characteristics that are quantitatively evaluated by diagnostic characteristics. The analysis of the applicability of various methods for diesel engine (as an example) diagnosing shows that diesel engine malfunctions can be detected with the help of four basic methods: thermodynamic, parametric, spectral (‘metal in the medium’), vibroacoustic.
Considering the variety of primary transformers, secondary equipment and methods of the signal processing by all these methods we must conclude that the application of vibroacoustic method enables significant reduction of the costs of development, implementation and operation of the system for reciprocator technical diagnostics.
Naumenko A.P. The problems of reciprocator diagnostics // Nauka, obrazovanie, biznes (Science, education, business). - 2007. - pp. 84-92
Progressive physical and moral deterioration of electric multiple-unit train fleet necessitates ensuring of the required level of safe running as well as fulfillment of a train schedule by increasing the reliability and operational readiness of rolling stock. Statistical data analysis shows that electric apparatus of electrical control circuits of traction electric drive cause up to 40% of failures, inadequate quality of maintenance and operating repairs, which are carried out at railway repair services, cause 75% of failures.
The lack of technical equipment and methods of getting of objective information on the quality of repairs determine such situation. In this regard the task of technological retooling of railway enterprises (with large-scale implementation of advanced technologies and modern means of objective control of rolling stock condition - the means of technical diagnostics) becomes urgent.
The study of physical properties and malfunctions of diagnosing object and development of its diagnostic model, which is necessary for diagnosing algorithm construction, must be a preliminary to development of the tools for technical diagnosing.
Functional-logic model reflects operating mode of equipment and order of its starting. In addition, such model determines the structure of hardware and software system, its equipment and diagnostic program. A diagnostic program in turn determines a necessary sequence of actions that is specified according to the train operating condition - a functional-test diagnostics.
The analysis of the object diagnostic models enables to formulate the efficiency condition, to determine the malfunction criteria and to select a limited set of characteristics, indexes or parameters, which should be controlled during the process of diagnosing. When choosing the methods of diagnostics it is necessary to take proper account of the possibility of their technical realization, embodiment and operating conditions of the object.
KostyukovV.N., Kazarin D.V., Kashkarov P.B. Diagnostic model of electrical control circuits of traction electric drive of electric multiple-unit train // Nauka, obrazovanie, biznes (Science, education, business). - 2007. - pp. 80-84