Abstract A flexible loop, hard slot coil is described wherein the preformed coil is wrapped over the entire coil length with a single micaceous insulating tape. The resin system applied between tape layers wrapped about the slot regions of the coil, however, contains a greater weight percentage of cross-linking catalyst than is contained in the resin system applied atop the loop regions of the coil to produce a differential cure rate for the different sections of the coil, i.e., the resin system in the slot sections of the coil becomes fully cured during subsequent baking of the coil while the resin system in the loop portions of the coil remains partially cured to retain flexibility therein. Flexible loop, hard slot coils also can be fabricated by varying the weight percentages of epoxide resins forming a resin blend to produce a more rapid cure rate in the slot portions of the coil relative to the loop portions of the coil. The resultant flexible loop, hard slot coil not only facilitates winding of dynamoelectric machines by permitting ''''raising of the jump'''' in a cold state but also eliminates the need for a high degree of precision in the drop angle of the coil loops.
A method of winding a dynamoelectric machine according to claim 1 wherein said differential cure rate is achieved by coating the tape with a single insulating resin system containing differential quantities of a cross-linking promoter in the slot regions relative to the loop regions of the coil.
Claim 2
Dependent Claim
27 words
A method of winding a dynamoelectric machine according to claim 2 wherein said resin system applied to the loop regions of the coil contains no cure promoter.
Claim 3
Dependent Claim
60 words
A method of winding a dynamoelectric machine according to claim 1 wherein a differential cure rate is achieved by coating the tape with a blend of epoxy resins having different degrees of functionality and composition, the relative percentages of said resins in said slot regions differing from the relative percentage of said resins in said loop regions of said coil.
Claim 4
Dependent Claim
68 words
A method of winding a dynamoelectric machine according to claim 1 further including wrapping said coil with a release tape subsequent to wrapping the coil with the resin coated tape, applying vacuum to said dual wrapped coil to remove volatiles, pressurizing the coil with a gaseous atmosphere and subsequently curing the insulation system on the coil for the period required to produce a hard slot, flexible loop coil.