Der Hysteresissprung bei der Induktionsmaschine

Unger, Franz

It is shown that the eddy currents in the rotor of an induction machine produce a torque proportional to the slip according to the general relations between torque, electrical rotor power and mechanical power. This torque can be dealt with in the same way as the torque of the rotor currents, the same torque producing flux being influencing both. Conditions are quite different for the rotor hysteresis, the rotor hysteresis torque being constant and only reversing its sign in synchronisme. This power jump, the hysteresis jump, means an alteration of the direction of energy flow through the air gap of the induction machine without load. It was found that the ratio of the total rotor iron losses to air gap power of the eddy currents and hysteresis is equal to the slip, in analogy to the well known relations between slip, electrical rotor power and air gap power of a loaded induction machine. In a table and several figures the conditions are illustrated as a function of slip. It is shown how the circle diagram must be altered as a result of the reflexions. The diameter of the circle remains constant but direction and size of no load current in synchronisme will be altered. The eddy currents of the rotor alter the short circuit point and the power line while the hysteresis torque causes a parallel shift of the torque line (to the bottom in case of subsynchronisme, and to the top in case of hypersynchronisme) whereby the bearing friction loss may be included. The mechanical useful power of the motor or the driving power of the generator respectively is found by the diagram and simple calculation.




Unger, Franz: Der Hysteresissprung bei der Induktionsmaschine.


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