3.1 LARGE FLAKE MICA, POLYESTER RESIN VPI PROCESS
In Manitoba Hydro the largest number of units with large flake mica bonded with polyester resin by the VPI process are the twelve units rated 13.8 kV, 120 MVA 90 rpm installed at Kettle during the period of 1970 to 1974 (Table 5).
Each stator has 600 slots with a total of 24circuits with 25 three-turn coils between line and neutral.
The stator core and frame together with factory installedstator coils was shipped to site in four sections.
There are normally 38 coils in a lift and these coils are heated to 110 oC at the knuckle. Single coils are heated to between 70 and 80 oC prior to insertion.
The coils were supplied with an asbestos armour tape in the slot section and there
was no side packing.
As these coils have a stress control coating on the end arms in-stator measurements of Tan δ
tip-up are of limited value because guard electrodes cannot be applied [14].
FLAKE