Actual situation, when the rolling stock is maintained for appropriate condition due to the schedule-based preventive repair, suggests large resources costs on carrying out the planned repairs irrespectively of the actual condition of any MDRS-section unit. At the same time, the covert nature of defect nucleation and fault development leads to MDRS sections unscheduled decommissioning and additional costs.
An above-mentioned problems solving can be reached by means of an on-board condition monitoring system, making a real-time assessment of the each unit condition and giving information about the expediency of further operation. The efficiency of such a system consists in its continuous operation, i.e. the period of diagnosis, which is much smaller than fault development period in critical (emergency) condition, which gives an opportunity to carry out a condition-monitored operation of the machinery, avoiding the resource-intensive schedule-based preventive repair system.
The failures distribution analysis by the main groups of MDRS equipment shows a relatively high percentage of auxiliary machines faults in operation, it is about 10% and 20% of the detections during the repair and maintenance. The continuous condition monitoring of the auxiliary machines allows to minimize the costs for carrying out the schedule-based repair arrangement and to maximize its resource. In this case, the repair should be conducted only on those units, which are really in need of it in the required amount.
Tsurpal A.E. Failure analysis of supporting machines of motor driven rolling stock (MDRS) for its diagnostics // Science, education, business (“Nauka, obrazovanie, biznes”). - 2011. - pp.222-223
Statistical data about the traction motors failures, constituting more than 20% of the service failures total number, demonstrate the repair quality and motors testing at the repair enterprises. Thus, 65% of the motor failures occur for reasons of an electrical nature, such as: electrical breakdowns and turn-to-turn fault of armature winding, the main and additional poles, compensating windings. That testifies availability of factors, adversely affecting the dielectric resistance of the windings insulation. The suggestions for significant simplification of the traction electric motor testing process after repair, especially in the current repair № 3 process, are wrong.
Long-term experience in traction electric motors testing shows, that every month during the testing the 10-15 % of traction electric motors are identified with significant deviations in after-repair switching conditions at the Zheldorremmash plants.
On the assumption of the above-mentioned problems we suggest to tighten the control of testing and diagnostics of traction electric motors and fully automate the diagnostic complexes.
Melk V.V. Diagnostics of electric-driven rolling stock traction motors. Methods, types and main faults // Science, education, business (“Nauka, obrazovanie, biznes”). - 2011. - p. 184
A mathematical description for structure of a vibro-acoustic signal, obtained from a piston compressor specific assemblies with regard to the channel of vibro-acoustic oscillations formation and propagation, is a diagnostic model. This model allows to select the informative diagnostic features of the assembly malfunctions and defects.
One of the piston compressor most "problematic" assemblies is its valve. Number of valves per one cylinder usually ranges from four to eight and more. The report considers the model of vibro-acoustic oscillations, which have been converted into an electrical signal by dint of a sensor, mounted directly on the piston compressor valve or next to the valves group.
When considering the model, it was found that with an appropriate choice of locations for the vibro-acoustic signals sensors (on the piston compressor appropriate assemblies) one can diagnose the malfunctions occurrence in a double-acting piston compressor assemblies according to correlation of the second and more high-and low-frequency harmonics levels in an envelope spectrum of vibro-acoustic signals. Taking into account a modulation degree high sensitivity to changes in a modulating signal parameters, compared with a direct spectrum signal, it is advisable to use the frequency range that corresponds to a carrier frequency in vibro-acoustic oscillations, generated by gas flow.
Thus, the presented model of the vibro-acoustic signal allows to determine the most informative vibro-acoustic components, which can be used as the diagnostic features parameters for malfunctions in valves and other piston compressor components and parts.
Naumenko A.P. Patterns for vibro-acoustic signals of piston machines // Science, education, business (“Nauka, obrazovanie, biznes”). - 2011. - pp. 114-120
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