| 摘要 |
<p>An immersed asynchronous electrical motor (1), particularly suitable to drive hydraulic lifts and hoists, having a ferromagnetic material mass (6) arranged at one side of the rotor (4). The rotor (4) and the mass (6), rigidly secured in rotation to each other, are axially displaceable along the shaft (5) of the motor (1) upon start. During the initial start-up phase the entire mass (6) and only one portion of the rotor (4) are positioned inside of the stator (2), whereby the mass (6) determines a high reactance and the residual operative flux, pertaining to the portion of the rotor (4) located inside of the stator (2), generates reduced starting torques, with reduced input starting currents, causing rotation and progressive axial displacement of the rotor (4) and mass (6). At the end of start the entire rotor (4) is inside of the stator (2), so as to obtain the normal motor performance. The motor (1) is thus self-limiting the input current also in case one supply phase is missing or in case of wrong rotation direction. <IMAGE></p> |
