Forward stall test: an alternate method of rotor and stator loading for temperature and vibration verification

The loading of induction machines for the purpose of determining the electrical and mechanical performance of a machine at rated temperature and load has presented problems for both manufacturers and users as machine sizes have outstripped the capacity of conventional dynamometers. A number of techniques has been developed that electrically load the stator and, indirectly, the rotor but not all users have been convinced that the rotor heating and mechanical vibration are the same as expected under a full mechanical and electrical load. This paper shows that the stator and rotor temperature rises are close to direct loading and that the vibration is similar for an alternate method of loading called the forward stall method. At the same time other methods are presented and compared