power to move the world
I N S U L A T I O N
Vacuum Pressure Impregnation (VPI) System
The Hyundai Ideal Electric Company
(HIEC) insulation system is a proven
insulation system based on a global
Vacuum Pressure Impregnation (VPI)
method using mica tapes combined
with epoxy resin. Global VPI is a
widely used insulation method in
the electric machine manufacturing
industry. HIEC uses epoxy resins in
the VPI process as they have been
shown to be superior to the other VPI
resin types. This insulation system is
employed over the full range of form
wound machines produced by HIEC.
HIEC Insulation System Features
Class F (155°C) Temperature Rating
Voltages up to 15 kV
Mica Insulation combined with
Epoxy Resin VPI
Excellent Chemical, Oil, and
High Dielectric Strength with Low
High Mechanical Strength HIEC Insulation System
High Thermal Conductivity for
grading tape is applied to the coil from
Improved Heat Transfer VPI Process
the end of the slot and extending up
Withstands Starting and Short the coil end turn. The fully insulated stator is preheated
Circuit Stresses, Voltage Surges, in an oven to drive off any moisture
and Thermal Cycling. The coils are installed in the stator
or volatile components. The stator
slots and retained with segmented slot is moved to the vacuum pressure
wedges covering the full length of the
Coil Construction core. Absorbent polyester felt spacer
impregnation tank where a vacuum
is drawn removing nearly all the air
The coils are manufactured from blocks are installed between the coil
from the insulation. Epoxy resin is
insulated copper conductor wire. end turns. In addition, the coils are admitted to the tank while still under
Various combinations of conductor individually tied to heavy fiberglass vacuum to fully cover the stator. The
and turn insulation are used most rope rings to form a completely vacuum is released and pressure
employing mica turn tape to ensure arch bound system with exceptional applied over the resin covered stator
high turn to turn impulse voltage radial support yet allowing for axial to force the resin completely into
withstand capability. Ground insulation movement due to thermal expansion. the insulation materials. Winding
consisting of multiple layers of This end turn support structure is capacitance is monitored during the
fiberglass backed mica tape is applied thoroughly saturated with epoxy resin VPI process to assure complete resin
to the entire coil to a thickness based during the VPI process and when cured penetration of the insulation materials.
on machine voltage. A conductive forms a rigid support ring for the coils. After removing the stator from the
tape is applied over the mica as a final The coil and stator lead connections VPI tank, the stator is placed in an
layer on the slot portion of the coil to are insulated with the same mica tape oven and baked to cure the resin and
suppress corona discharge. At higher used for coil insulation. fully develop the properties of the
voltages, a semi-conductive stress insulation system.
Checks on stator coils to assure
dimensional uniformity and proper
fit of coils in stator slots.
High potential tests of coils during
coil installation and prior to VPI.
Turn to turn insulation tests of coils
prior to VPI.
Periodic tests of epoxy resin system.
Periodic tests of power factor tip-up
per IEEE Standard 286 to monitor
insulation system performance.
Final high potential test of
completed winding after VPI at twice
rated voltage plus 1000 volts.
Repaired stator being lowered into HIEC VPI tank
Bakeout Oven used to cure VPI epoxy resin
Our mission is to produce
the highest quality product,
satisfy customer requirements,
and provide rewarding
employment in a profitable
14-foot diameter VPI tank
growth environment, while
This eco-friendly product is printed using soy-based inks on paper which is acid-free, contains 50% recycled content including
supporting the community.
25% post-consumer waste, is bleached without using chlorine and the wood pulp is harvested from sustainable forests.
Certificate Number 31576
330 East First Street • Mansfield, OH 44902
phone 419.522.3611 • fax 419.522.9386
w w w . I d e a l E l e c t r i c C o . c o m