Brochure

Vacuum Pressure
Impregnation (VPI)
Void free insulation is vital for the life
of medium and high voltage insulation
systems. The stator is heated in an
oven to dry out any moisture. Then it
is placed into a pressure vessel where
the lid is vacuum sealed. Then resin,
at varying temperature, is pumped
into the chamber to fill all voids on the
stator. After a period of time, dry air
is pumped into the top of the vessel
creating a “pressure blanket” over the
resin, “pushing” it into all remaining
voids. The pressure is then released
and the stator is placed in an oven for
Coil Windings
Stator coils are produced from
annealed copper strips insulated
with a number of layers of mica
tape under armour finishing tapes.
The coils are inserted into stator slots
using protective liners to prevent
damage and are firmly positioned
with epoxy glass wedges. The end
windings are then securely braced
the resin to cure. The stator is rotated
during the curing process to ensure
that the resin does not run-off and is
even throughout.
before the complete wound stator
undergoes a VPI process.
11 GE I Power Conversion