Design of Pre-Pressing Tool for Straightening of Stator Bar of a Hydrogen-cooled Generator

Insulation system of heavy generators as the converter of mechanical power to electrical power, is the centerpiece to determine the machine reliability and life-time. The global vacuum pressurized impregnation (GVPI) insulation system is recognized as the most applicable electrical insulation system compared to winding VPI. According to the GVPI process of generators, the life of the bar is determined by its insulation and the life of the generator is determined by its bars. Aging due to this type of activity can completely be avoided by ensuring that no voids are left during the manufacturing process of the stator bars. For this purpose, before inserting the bar into the stator slot, it must put under pressure in order to remove the voids and gap between its layers and to be straight as much as possible. In this way, it is needed to design and construct a pressing tool such that its strength should be investigated. Pre-pressing process should be implemented in such a way that, in addition to remove the voids of bar as much as possible, the straightness of bar is within the allowed range of its predicted tolerance; In this way, the stator bar can easily be inserted in the stator slot without any extra manual pressure. Finite element (FE) analysis of the designed structure of the pre-pressing tool was conducted to investigate its safety. The FE results showed that the structure and stator bar, both were in good stress condition.

کلیدواژه ها:

hydrogen-cooled generator ، stator bar ، pre-pressing tool