Development, calculation and research of semi-conducting system for capacitive currents routing in high power turbogenerator high voltage air-gap armature winding

Different variants of locating and fastening the high voltage stator winding in the air-gap of a high power generator have been analyzed, and anti-corona protection and capacitive current routing systems for those variants have been classified. The variant having a multilayer air-gap winding with semi-conductive coating in an active zone has been studied. Capacitive currents from the upper layers of that winding reach the iron core of the stator only through the semiconductive layers of the fastening system and the semiconductive coating of the bottom winding layer. A fastening system components with semi-conductive structures have been designed. The method of calculating currents through semiconductive layers of winding and fastening system parts, and solutions for limiting those currents have been developed. The nomogram and the method for calculating the optimum parameters for semi-conductive layers have been developed. Air-gap winding and fastening systems with semiconductive layers have been tested on a full-scale model and evaluated under conditions of increased voltage and continuous aging.