Electric machine rotor and rotor ring assembly - using copper ring shrink fitted over rotor with layer of copper strip in-between to fill voids

摘要

The electric machine has a ring force fitted over the rotor exterior to provide a return path for sub-synchronous current transients arising during abnormal operating conditions. The ring is manufactured from a malleable electrically conductive material, for example copper. - The ring (14) is placed so that it acts as a rotor retaining ring, and is fitted by firstly heating the ring to expand its diameter till it is marginally greater than the exterior diameter of the rotor (12), fitting the ring, then cooling the ring till it reaches the rotor temperature. In addition a band (20) of the ring material is placed between the rotor exterior and the ring interior to remove any voids between rotor and ring.