A METHOD AND A DEVICE FOR REDUCING THIRD HARMONIC PHENOMENA IN A ROTATING ELECTRIC ALTERNATING CURRENT MACHINE

摘要

In a method for reducing the influence of third harmonic voltages upon direct connection of alternating current machines (1) to a three-phase power network (5), wherein at least one winding of the machine is Y-connected and the neutral point (2) of the winding is available, a suppression filter (14) is connected between the neutral point (2) and the ground point (4) of the power network. The characteristic of the filter alters in the event of risk of the filter getting into third-harmonic resonance with the network and the machine. In such a device, altering means (20, 21) are provided to alter the characteristic of the filter (14).