Grounding of outer winding insulation to cores in dynamoelectric machines

A core and coil structure for a dynamoelectric machine comprising a stack of laminations formed with slots for receiving sides of coils;

• and a winding of coils having sides disposed in said slots and end turns projecting from the core stack, each one of said coil sides having at least one conductor strand encased in a hard, unyielding jacket of insulating materials and the jacket of insulating materials covered by a hard, unyielding, semiconducting armor jacket;
• variations in the laminations and the surface of said armor jacket defining voids between the armor jacket and the slot wall;
• the improved means for conducting electric charge from said armor jacket to said core stack comprising a pressure deformable, semiconducting material located continuously between said armor jacket and said slot wall, said semi-conducting material being deformed by pressure into said voids and having an electrical resistance low enough to conduct electric charge from said armor jacket to said core stack and high enough to avoid significant eddy current flow between core laminations;
• and, wherein said semi-conducting material is a room temperature vulcanizing silicone resin filled with fine particle graphite and/or lamp black in an amount that gives the filled resin an electrical resistance within an approximate range of 1000 to 80,000 ohms per square.