The questions on defining the mechanical state of collector-brush units in dynamic modes applying the techniques of result processing obtained with use of contactless profilometer developed in TPU have been considered. The results of experimental researches of the collector-brush unit mechanical state of the electric motor with alternating current during the process of resource operating time are introduced. The experimental data are analyzed. Recommendations on improvement of current collection conditions in sliding contact and increasing of brush resource are develope

Kachin, O. S.

Electronic archive of Tomsk Polytechnic University

REFERENCES1. Chebaevskiy V.F. Pump station design and pump unit test. – Moscow: Kolos, 2000. – 376 p.2. General course of the processes and devices of chemical engineering/ Ed. by V.G. Ainshtein. – Moscow: Khimiya, 1999. – 888 p.3. Gritsenko K.G., Tolbatov V.A. Chervyakov V.D. The universal model of pump station flowsheet // Problems of control and information science. – 1998. – № 4. – P. 106–111.4. Tysivskiy I.V., Gritsenko K.G., Chervyakov V.D. Resourceseconomy control of pump electric drives of public water supply system //Problems of the automatic electric drive. Theory and practice:KhGPU Bulletin. – 1998. – P. 237–238.5. Tolparov D.V. The efficiency of using pumps with the builtin frequency converters in systems of ventilating, heating and water supply //Equipment – region. – 2006. – № 3. – P. 23.Received on 03.10.2007Bulletin of the Томsк Pоlytеchnic University. 2007. V. 311. № 4112The increase of communication reliability and resource of modern highspeed commutator machines isdetermined to a large extent by mechanical stability ofelectric sliding contact (SC). However, SC behavior indynamics is not studied enough theoretically and experimentally owing to the process complexity as well as theabsence of special measuring systems and techniques ofprocessing measured information [1–4].The aim of the carried out researches was to test thetechniques developed in Tomsk Polytechnic University(TPU). They allow extracting the information interesting for the designers of commutator electric machinesabout a change of collector profile at maintenance,about the value and character of armature chatter aswell as about the other mechanical parameters from thewhole array of the results of measuring carried out withapplication of contactless profilometer. On the basis ofthe carried out experimental investigations and furtherdata processing with application of the developedtechniques the separation of the initial array of sourceinformation into components characterizing the collector surface levels without armature chatter and changesof these levels owing to armature chatter was carriedout. As a result, the quantitative information about thestate of collector profile of highspeed electric machine,size and character of bearing armature chatter, as well asthe degree of their influence on mechanical state of collectorbrush unit (CBU) at resource operating was obtained. The data obtained during investigations shouldbecome a base for modeling dynamic processes in SCand working out references concerning the increase ofCBU working resource.The test subject: electric motor of vacuumcleanerunit of LG Electronics company, VCE280E02 model,35000 rev/min, 1800 W, electric brushes of HG25 type.During the tests the electric motor operated withventilator load. Endurance test duration amounted to709 hours. Brush wear was measured by a micrometerwith interval of 35...45 h. Collector profile of electricmachine was measured as well in dynamics at rated revolutions with the use of contactless hardwaresoftwaremeasuring system developed in TPU [5]. All the graphic materials introduced in this article are constructed onthe basis of experimental data and their mathematicalprocessing by special techniques.The experimental data obtained during resourcetests show that at brush limiting wear of 28,8 mm(1900 mm3) the collector sliding path wear amounted to0,74 mm (532 mm3). It indicates the triple collector resource stock in comparison with brush set resource (onthe basis of the constructive included stock for lamelwear amounting about 2...3 mm [6]). Therefore, theincrease of CBU resource in similar machines is possible by decreasing the intensity of electric brush wearwhich depends on the factors of friction, electrocorrosion (current) and electroerosion nature. The electroerosion component of SC element wear is the most significant and determined by the commutation characterwhich is conditioned to a large extent by collector profile state and armature chatter.Distances form measuring transducer (eddy currenttype) stationary relative to the studied electric motorbody to collector working surface in rated duty were meUDC 621.313.36DIAGNOSING THE MECHANICAL STATE OF THE COLLECTORBRUSH UNIT OF THE HIGHSPEED ELECTRIC MACHINE AT RESOURCE TESTSO.S. KachinTomsk Polytechnic UniversityEmail: kos@tpu.ruThe questions on defining the mechanical state of collectorbrush units in dynamic modes applying the techniques of result processingobtained with use of contactless profilometer developed in TPU have been considered. The results of experimental researches of the collectorbrush unit mechanical state of the electric motor with alternating current during the process of resource operating time are introduced. The experimental data are analyzed. Recommendations on improvement of current collection conditions in sliding contact andincreasing of brush resource are developed.Power engineering113Fig. 1. Collector profile change during resource operationНомер ламели – Lamel numberasured with the use of contactless diagnostic system [5].It allowed determining the change of collector profile atmaintenance, the magnitude and character of armaturechatter using the techniques developed in TPU. It allowed as well determining other parameters characterizing CBU mechanical state on specified time interval ofresource operating.The changes of collector profile of the studied highspeed electric machine during endurance test are illustrated in Fig. 1. In the left part of the Figure the collector profile sweepings relative to mean lines of properprofiles at resource operating are given. In order to improve the perception of the collector crosssection geometry the collector profiles at resource tests relative toideal circles (mean lines) reduced to the level of 100 ?mare introduced in the right part of Fig. 1. As it is seenfrom the given diagrams, the collector geometry changes greatly during the electric motor service life. In particular, the profile intensive changes occur after 350 h ofoperation i.e. after electric motor yield about a half ofbrush resource.The dynamics of changing the values of dropsbetween the collector adjacent lamels in the process ofresource operating is introduced in Fig. 2. It followsfrom the given data that the peak values of drops between the lamels during the resource tests increased in 7,8times and an average value of drops along the collectorcircle increased in 13,5 times.Fig. 2. Dynamics of changes of peak (———) and average (– – –)values of drops between the collector lamels along thecollector circle during the resource testsIt is seen from Fig. 2 that during the first 220 h ofelectric machine operation the peak values of dropsbetween lamels decrease by a third, average value ofdrops along the collector circle decreases as well but insignificantly (83,5 h – 0,34 μm, 215,5 h – 0,32 μm).This indicates that collector runsin at this stage. Thenthe collector geometry impairs stepbystep during operation.It is known [7, 8] that at vibration signal decomposition from body of revolution into Fourier series thefirst harmonic characterizes eccentricity, the secondone – ellipticity and the third harmonic characterizestriangle feature. The obtained data indicate the fact thatduring the first 220 h of electric motor operation theamplitudes of the specified harmonics decrease or increase slightly (eccentricity) – the collector surface runsin, then the harmonic amplitudes increase. Eccentricityduring the electric motor operation grew in 21,2 times,ellipticity in 5,6 times and triangle feature in 7,7 times.The introduced data show one more time the collectorprofile degradation in the process of resource operation.According to the technique developed at the department of electric drive and electric equipment (EDEE)of TPU the brush accelerations conditioned by the action from the side of collector working surface were determined. The dynamics of changing an average acceleration of brush during the electric machine service life isshown in Fig. 3.Fig. 3. Dynamics of changing brush average acceleration conditioned by the action from the side of the collector workingsurface during resource testes of the electric machineУскорение, м/с2 – Acceleration, m/s2; Время, ч – Time, hAn area of collector runin is seen as well from thedata introduced in Fig. 3. After it the acceleration amplitude grows at increase of electric motor operatinghours. This indicates degradation of the collector working surface geometry owing to unequal wear and, probably, integrity deterioration because of stress reductiondue to mechanical and thermal actions on collector.Average values of accelerations influencing the brushfrom the side of the collector surface during the electricmotor resource tests increased in 6,5 times.Using the original techniques developed in TPU theinformation on armature chatter parameters which aremainly conditioned by bearing vibrations (radial motions of inner race relative to exterior ring surface owingto inaccuracy of bearing element manufacturing andtheir wear) was obtained. The dynamics of changing thearmature chatter maximums conditioned by bearing beating at electric motor operation is introduced in Fig. 4.As it is seen from the given diagram, maximum swing ofarmature chatter increased in 5,9 times during the resource tests.Using the data on the armature chatter of electricmachine its vibration velocity and vibration acceleration may be determined. The dynamics of changing anaverage value of vibration acceleration of electric motorarmature at electric machine service is introduced inFig. 4. It is seen from the diagram that the average valueof vibration acceleration of electric motor armature increases at resource operation and exceeds the initial value in 6,6 times at final stage.It should be noted that during the resource tests thevibration action of the electric motor armature onbrushes were about 1,6 times higher in comparison withsimilar actions of the collector profile that is, probably,typical for the highspeed machines.Bulletin of the Томsк Pоlytеchnic University. 2007. V. 311. № 4114Fig. 4. Dynamics of changing the armature chatter maximums(–––) and average value of armature vibration acceleration of the electric motor (– – –) during the process ofresource operationУскорение, м/с2 – Acceleration, m/s2; Время, ч – Time, hPossessing the data on average values of brush acceleration caused by the action from the side of the collector surface ащ.кол, as well as the data on average vibrationaccelerations of the electric machine armature ащ.якоря,influencing the brush owing to vibrations in bearingunits the summary average vibration acceleration (maximum average vibration acceleration) of the brush atelectric motor operation: ащ.сум=ащ.кол+ащ.якоря may be determined. Change of the average summary vibration acceleration in the process of resource tests of electric motor is reflected in Fig. 5.Using the data on the brush wear as well as its density the dynamics of changing the brush weight mщ may bedetermined. And using the value of pressure spring stiffness coefficient of (this case k=48 N/m) the maximumbrush acceleration provided by the pressure spring atany time moment at electric motor maintenance may bedetermined, Fig. 5.Fig. 5. Acceleration of the pressure spring (–––) as well as thesummary average vibration acceleration of the collectorand bearing units of the electric motor (– – –) during theprocess of resource operationУскорение, м/с2 – Acceleration, m/s2; Время, ч – Time, hAs it is seen from the introduced data the summaryaverage vibration acceleration (of collector and armature) increased in 6,5 times and achieved the limit valuefor normal operation of collectorbrush unit during theelectric motor operation. This indicates the fact that atsome moments of time the failure of mechanical contacting in sliding pair brushcollector (brush hanging,commutation failure and as a result, the increased wearof SC elements) is possible.Analyzing Fig. 5 the conclusion may be drawn thatthe reliable contacting in sliding contact brushcollectorshould be provided at final stage of electric motor maintenance for further increase of electric motor service life. It may be achieved either by adjustment of the pressure spring acceleration (it is necessary that the acceleration curve increases more steeply at final stage) or byadjustment of the curve of summary average vibrationacceleration of collector and armature of the electricmotor (it is necessary for the curve to be flatter and foracceleration value to decrease at final stage). In otherwords it is necessary to achieve the parallelism of thepressure spring acceleration curve and the curve of summary average vibration acceleration of collector and bearing units.The curve of the pressure spring acceleration may beadjusted by the change of spring type, screwdown arrangement type and brush type.The curve of summary average vibration acceleration of electric motor collector and armature may be intheir turn adjusted by improvement of collector strengthproperties, decrease of sparking degree and, respectively, wear of collector working surface (for example, byoptimization of electromagnetic condition of commutation process), application of more qualitative and wearresistant bearing.Thus, from the obtained experimental data the trendto collector profile degradation with its wear is clearlyobserved. The increase of vibrations and vibration accelerations conditioned by the action from the side ofelectric machine armature is also observed that indicates the wear and incipient defects in bearing units.It should be noted that during the resource tests thevibration influence of electric motor armature onbrushes was in 1,6 times higher in comparison with thesimilar actions of the collector profile.Therefore, one of the ways of prolongation of electric motor resource is to set up more qualitative, wearresistant bearings or application of improved lubricantsin them for extension of their resource. These measuresare required for decreasing bearing vibrations and vibration accelerations that improves commutation processesand increases the resource of collectorbrush unit.However, these measures need significant volume of additional experimental investigations and economic justification.The efficient direction of increasing brush resourceis application of new constructive solutions decreasingcommutation sparking and erosive component of wear[9, 10]. In this case the collector profile stability increases in time that allows reducing additionally the commutation sparking due to improve of mechanical state ofcollectorbrush unit at electric machine maintenanceand decreasing SC element wear.Power engineering115REFERENCES1. Hudson B. HV motor condition monitoring – the end user’s view //IEE Colloquium Design, Operation and Maintenance of High Voltage (3.3 kV to 11 kV) Electric Motors for Process Plant. – Glasgow,UK, 1999. – P. 7.2. Regan R.H., Wakeley K. Rotor monitoring and protection for largegenerators // Seventh International Conference on ElectricalMachines and Drives. – Durham, UK, 1995. – P. 203–207.3. Thorsen O., Dalva M. Condition monitoring methods, failure identification and analysis for high voltage motors in petrochemical industry // Eighth International Conference on Electrical Machinesand Drives. – Cambridge, UK, 1997. – P. 109–113.4. Ross W.H. Condition monitoring of electrical machines in ScottishPower // IEE Colloquium on Condition. – London, UK, 1995.– P. 3.5. Kachin S.I., Borovikov Yu.S., Nechaev M.A. Hardwaresoftware system for estimating the mechanical state of sliding contacts of thecollector electric machines of electric drives // Bulletin of the TomskPolytechnic University. – 2004. – V. 307. – № 1. – P. 140–144.6. Electric machine collectors / Ed. by B.N. Krasovskiy. – Moscow:Energiya, 1979. – 200 p.7. Russov V.A. Spectral vibration monitoring. – Perm: Vibrotsenter,1996. – 173 p.8. Goldin A.S. Vibration of rotor machines. – Moscow: Mashinostroenie, 2000. – 344 p.9. Pat. 2107375 RF. IPC6 H02K 3/12. Stator of the collector electricmachine / S.I. Kachin. Stated 13.05.1996; Published 20.03.1998,Bulletin № 8. – 5 p.: ill.10. Pat. 2277282 RF. IPC8 H02K 3/12. Armature winding of electricmachine / S.I. Kachin, Yu.S. Borovikov, O.S. Kachin. Stated16.03.2005; Published 27.05.2006, Bulletin № 15. – 10 p.: ill.Received on 04.07.2007Bulletin of the Томsк Pоlytеchnic University. 2007. V. 311. № 4116Considerable difficulties at adjusting switching ofthe direct current machines (DCM) are connected withknown disadvantages of rolling contact of brushcollector and its limiting switching capacity.Absence of influence of mechanical factors as well asdischarged atmosphere or mordant environment on rolling current collector makes it rather perspective for using in reduced conditions.The analysis of the existing current collecting devices (CCD) for the direct current machines using therolling contact shows that all similar devices do not possess switching capacity the same as the rolling contactpossesses.In this connection a new method of rolling currentcollector was proposed [1]. The matter is in using additional link – rolling rollers (circles) providing electriccontact between rotating collector and stationary«brushes» (Fig. 1).In order to provide the switching capacity of such device its «brushes» should be compound with increasingresistances of their elements to the leaving edge [2, 3].In Fig. 2 the typical examples of dependences of«brushes» resistances on the place of contact with themfor reversible (solid line) and irreversible machines (dotted line) are introduced. Rmin and Rmax note minimal andmaximal resistances of «brush» components (C), bщ isthe «brush» width.Fig. 1. Current collecting device for DCMFig. 2. «Brush» resistance from the place of contact with roller0R(b)b b?RmaxRmin?????????????????????????????????«?????»??????????????????????????????????????????????????????????????????V??????????V??????UDC 621.313ROLLING CURRENT COLLECTOR IN DIRECT CURRENT MACHINESV.D. Avilov, D.I. PopovOmsk state university of means of communicationEmail: emoe@omgups.ruThe new method of rolling current collector has been developed. Its theoretical research was carried out. The operating model sample ofthe current collecting device using the rolling contact was made.

Diagnosing the mechanical state of the collector-brush unit of the high-speed electric machine at resource tests

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