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rotor turn insulation

Rotor Insulation

Electric generators contain a rotating rotor that induces an electric field into the stator winding to produce electric current. Electrolock’s rotor insulation is used to insulate copper turns in these rotor windings, providing a dielectric barrier between copper bars that carry current. Insulated copper bars are stacked into a metal slot through the length of the rotor.

Electric generators require some repair as the rotor ages, including turn-to-turn shorts, field grounding, thermal failure, contamination, retaining ring failure, or creep from centripetal forces in the winding. Copper turn shorts can result from insufficient bonding of the rotor turn insulation to the copper. Electrolock tests the thermal aging properties of rotor insulation during the qualification process and applies a special adhesive system to provide the proper bond to copper turns. Rotor turn shorts can produce enough heat to melt the rotor.

Rotorsproduce very large centripetal forces, creating strain and compression on the turn insulation.  There can be vibration and copper movement as the winding thermally expands under load. The adhesion of the insulation to the copper is critical to maintaining the dielectric barrier throughout the operating cycles of the generator.  There are cooling slots in the copper turns that must remain clear when insulated with pre-slotted rotor insulation. These slots must be fabricated precisely to match the slots in the copper winding.  Electrolock considers all these factors in the design and manufacturing of rotor insulation to provide our customers with continuous operating success, avoiding copper turn shorts, or blockage of vent holes.