FIELD: electrical and electromechanical engineering; large electrical machines such as turbogenerators. SUBSTANCE: method for diagnosing interference fit of banding ring on rotor barrel at joints between end and face parts and between banding ring and alignment ring without rotor disassembly includes estimation of changes in interference fits at seating points of banding ring on rotor barrel and on alignment ring which is determined by comparing results obtained in measuring banding ring diameter at seating points before placing turbogenerator in operation and in the course of its shutdown. According to first option, comparative measurements are made on external, non-fitting diameter of banding ring and interference fit Δδband is found from equation Δδband = (λband-λrot)/(Doutbefore-Doutafter), where λrot and λband are, respectively, coefficients of pliability of rotor barrel and binding ring at seating point, m/n; Doutbefore and Doutafter are outer diameters of banding rings measured, respectively, before and after press- fitting of ring on face part of rotor barrel during assembly of banding unit, or during scheduled shutdown of turbogenerator as compared with measurements made earlier. According to second option, changes in interference fit of binding ring at its seating point on alignment ring that has tangential slits are determined from equation 
, where ΔaI, ΔaII, ΔaIII, ΔaIV are, respectively, changes in sizes of tangential slits in diametrically opposite areas; Doutbefore and Doutafter are above-mentioned diameters of binding ring. EFFECT: provision for diagnosing interference fits of binding rings without rotor disassembly. 2 cl, 5 dwg
