Abstract
This paper focuses on the evolution of instantaneous supplying current absorbed by an AC motor used to drive a lathe headstock gearbox during a transient regime characterised by a strong acceleration and deceleration and a strong variations of the absorbed active electrical power (with positive and negative power flows). A relationship between the current root mean square and active electrical power evolutions was established and proved in experimental terms. A severe limitation of the electrical current evolution was revealed: the impossibility to describe a negative flow of absorbed electrical power.