Method for indirect estimation of the electrical machine stator winding insulation technical state

摘要

The invention relates to the technical diagnostics of the insulation state on the basis of radiointerference spectrum parameters nondestructive measurement methods, generated by partial discharges (PD).The frequency band, into which the measurements are performed, is determined in accordance to the radiointerference spectrum, measured by a meter or as a result of the spectrum, calculated according to the PD impulses duration period measurement results from the shunt by an oscillograph.The determination of such PD appearance is indirectly carried out as a result of the harmonics appearance having a high amplitude value, into the radioin-terference spectrum, in comparison with the neighbouring harmonics amplitudes and the amplitude reproportioning of these harmonics and harmonics spectrum absolute values change in time.According to the amplitude repropor-tioning of the isolated harmonics, if the proportion exceeds the 1,3 value, and the harmonics absolute values change in time, is estimated the insulation technical state. The decrease of the isolated harmonics amplitudes proportion, simultaneously with the harmonics spectrum amplitude absolute values increase, indicates to the PD high power impulses number increasing, which presents danger for the insulation. The attainment of this unit value proportion serves as a transition signal of the PD into a dangerous stage for the insulation.