Due to safety and economical reasons the interest to diagnostic and monitoring systems is growing rapidly in industry. Besides safety, there are quality control requirements. The greatest attention at machine-building enterprises is paid to quality control of working surfaces of commutators and contact rings of electric machines . However, the experience shows that the existing quality control is not efficient enough since it is functioning only in steady-state mode with the help of micrometer heads or industrial indicators and does not take into consideration the whole range of centrifugal, vibratory and temperature loads, influencing the commutator in working electric machine.
The majority of existing diagnostic systems are based on vibration diagnostic and they cannot provide information about cross section of rotating part or its surface quality. In order to fulfill these requirements, a diagnostic system ‘MICROCON´ was designed at Tomsk Polytechnic University. This complex is used for non-contact precision control of cross sections of shafts, commutators and contact rings of machines in static and dynamic modes, measurement of linear micro-movements and vibrations of machine parts.
Designed measuring complex has better technical characteristics compare to other systems due to original design of eddy current sensor, patented method of master correction of measurement results and special mathematical processing methods of measurement data. Eddy current sensor of measuring system has a narrow sensitivity diagram which allows differentiate profile levels of commutator plates with tangential dimension of 1.5 mm or wider.
‘MICROCON´ has high protection from external influences (dust, vapor, oil fog, etc.). It allows determination of object micro-movements, specific electric resistances, as well as surface temperature (if temperature via specific electric resistance is known). Non-contact measurement of specific electric resistance is especially important for thin-film structures supervision.
With the help of the designed diagnostic complex and special mathematical processing methods, the unique experimental data concerning the change of commutator profile of high-speed electric machines during the lifetime period, shape and value of bearing vibrations were collected.
1. Ross, W.H.: ‘Condition monitoring of electrical machines in ScottishPower´. IEE Colloquium on Condition, London, UK, 1995, pp. 3
The work was submitted to XIII international scientific conference on Modern Techniques and Technologies, Tomsk, Russia, 2007, came to the editorial office 16.01.2008.