Study on aging characteristics and lifetime model of polyimide film: A review

Increasing wind power generation quantity needs obviously reliable insulation property of power equipment. Since over 70% of the installed turbines utilize wound rotor induction machines (referred to as double-fed induction generators DFIG) , DFIG is deemed to be one of the most critical components of wind power systems and its performance directly influences the stability and reliability of wind power generation. However, insulating early failures occur frequently. Presently, polyimide (PI) film which has been widely applied in turn to turn insulation and turn to ground insulation of DFIG is a kind of basic insulating material. This technical review is carried out with the aim of describing the current state of the art in aging characteristics and mechanism research for polyimide film with a consideration of the complex operation condition and environment where it is in. The aging characteristics of PI film based on different analysis methods are described first. This is followed by a description of lifetime model of PI film for multi stress. It is intended that this review will provide the basis for future developments in study on the aging characteristics and mechanism of PI film.