Teeth Losses in Induction Machines

Izvedene su formule za proračun gubitaka vrtložnih struja u pravokutnim zubima. Pokazano je da se, uz pretpostavke da su permeabilnost i vodljivost lima konstantni, ukupni gubici vrtložnih struja mogu računati kao zbroj pulzacijskih i površinskih gubitaka. Date su upute kako se mogu računati ukupni gubici u zubima za sve oblike zuba uzimajući u obzir potiskivanje toka u limovima, prigušenje toka u zubima, te faktore obrade lima i paketa limova.Formulas that have been derived are used for calculation of eddy current losses in square teeth. It is shown that, assuming that permeability and conductivity of iron are constant, the overall eddy current losses can be calculated as the sum of pulsation and surface losses. Directions have been given on how to calculate the overall teeth losses for all forms of teeth taking into consideration skin effect of flux in lamination, damping of teeth flux and factors of iron sheet and core processing

Finite elements method calculation of circular magnetic flux emerged by eccentric position of rotor

Uzroci osovinskih struja kod niskonaponskih asinkronih motora (s homogenim jarmovima) napajanih iz mreže, uglavnom su ekscentrični pomak rotora u provrtu statora i nelinearnost krivulje magnetiziranja, koji dovode do nastanka kružnog magnetskog toka, a on nadalje uzrokuje osovinske struje, čiji strujni krug zatvaranja je: osovina, ležaj, ležajni štit, kućište, ležajni štit, ležaj i osovina. U radu je opisan postupak izračuna kružnog magnetskog toka koji određuje osovinske struje Metodom konačnih elemenata, kojim se može analizirati njegov iznos i harmonijski sastav.The main causes of shaft currents in the low-voltage asynchronous motors (with homogeneous yokes) supplied from the net are the eccentric position of rotor in the stator bore and nonlinearity of magnetizing curve of electrical steel of the motor stack lamination. Circular magnetic flux emerged by those causes, produces shaft currents closed in the circuit: shaft, bearing, bearing shield, housing, bearing shield, bearing and shaft. The article describes the calculation procedure of circular magnetic flux, which determines shaft currents, conducted by the Finite element method by means of which quantity and frequency spectrum of that flux can be analyzed

Uzroci osovinskih struja kod niskonaponskih kaveznih asinkronih strojeva

Possible origins of shaft currents in squirrel-cage low-voltage induction machines are analysed. The mechanism of generation of shaft currents fundamental frequency and slip frequency at 2-pole and 4-pole machines is explained, as well the influence of broken rotor bars or end rings on shaft currents.Analizirani su mogući uzroci osovinskih struja kod niskonaponskih kaveznih asinkronih strojeva. Objašnjen je mehanizam nastajanja osovinskih struja frekvencije napajanja i frekvencije klizanja kod dvopolnih i četveropolnih strojeva i utjecaji prekida štapova ili prstena rotorskog kaveza