Ein Beitrag zur Berechnung von Asynchronmotoren mit nichtisoliertem Läuferkäfig

SummaryAt non-insulated squirrel-cage rotors stray-currents may be caused through the fundamental wave and the harmonics of the rotor current within the rotor core. It is theoretically proved, that the influence of the stray-currents and their reaction on the air-gap leakage and the primary circuit can be taken into account by using a complex skewing factor χv* in the known equations of a squirrel-cage motor for the fundamental wave as well as for the harmonics instead of the normal skewing factor χv. This statement is not only valid for three-phase but also for two-and single-phase motors.The complex skewing factor χv* (eqn. 23/24) is a mere numerical quantity, which is expressed through the absolute value and the phase angle and which is only dependent from the geometry, the resistance and the slip of the rotor.The effect of the stray-currents is discussed with the help of two galvanic equivalent circuits and is demonstrated by numerical results achieved for a 4 pole 15 kW-motor.