FIELD OF THE INVENTION
[001] The present invention relates to the field of insulation systems for
industrial motors. The present invention in particular relates to class-
H insulation system for low voltage industrial machines.
BACKGROUND OF THE INVENTION
[002] The electrical insulation system for wires used in generators,
electric motors, transformers, and other wire-wound electrical
components is divided into different classes by temperature and
temperature rise. The electrical insulation system is sometimes
referred to as insulation class or thermal classification.
[003] The industrial machines typically use Class F insulation system
which is capable of withstanding a highest hot spot temperature of
155 ºC.
[004] Existing insulation system is based on mica and polyester/glass as
carrier and suitably impregnated with Bisphenol-A solvent-less
epoxy resin and hardener and it is limited to hot spot temperature
of class-F (155 deg. C) temperature.

[005] However when the temperature increases above 155 ºC, Class F
insulation system fails to insulate the motor of industrial machines
which results in the damage.
[006] Any voids and air inclusions in the insulation lead to ionization and
poor dissipation factor. Large sized and more no. of air pockets
contributes to less heat transfer and increased temperature of
machine. Hence, there is a need for better insulation system which
can withstand the temperature up to 180 ºC without damaging the
industrial machine.
OBJECTS OF THE INVENTION
[007] It is therefore an object of the invention to develop a class-H
insulation system for low voltage industrial machines
[008] A further object of the present invention is to develop a class-H
insulation system for low voltage industrial machines comprising of
Silicone based glass mica aramid fibre tape.
[009] A further object of the present invention is to develop a class-H
insulation system for low voltage industrial machines which is void
free, has better dielectric strength, better heat transfer and requires
less maintenance.

SUMMARY OF THE INVENTION
[0010] According to the present invention, a class-H insulation
system is developed, wherein the conductor insulation is made up
of fused corona resistant polyimide insulation and main insulation
is made up from silicone based glass mica aramid fibre tape, to
withstand the temperature as high as 180 ºC.
DETAIL DESCRIPTION OF THE INVENTION
[0011] The present invention is described in detail below.
[0012] The class H insulation system according to the present
invention comprises of a main insulation, conductor insulation,
stack pressing material, and lead emerging point reinforcement and
other general and supporting materials in coil.
[0013] The main insulation used is preferably a silicone based glass
mica aramid fibre tape and the conductor insulation is fused corona
resistant polyimide insulation.
[0014] The stack pressing material preferably used is Class H
Varnish and lead emerging point reinforcement is nomex felt.
While the other general and supporting materials in coil are
preferred to be polyimide film or polyamide based materials.

[0015] According to the present invention, silicone resin especially
for impregnating the windings of electrical motors. Applied by
vacuum pressure impregnation, it reliably protects the windings
against moisture by completely filling the spaces and coating the
surfaces. The liquid silicone resin is free of solvents and reactive
diluents. When cured, it meets all the requirements of insulation
classes H.
[0016] Advantages of VPI Insulation (Class-H) System
[0017] The VPI Insulation systems have the following advantages
1. Void free insulation
2. Better dielectric strength
3. Less corona discharges
4. Better heat transfer
5. More mechanical strength
6. Improved performance /cost effective
7. Requires less maintenance
8. Non-hygroscopic and dust free insulation
[0018] The invention has been described in an illustrative manner,
and it is to be understood that the terminology that has been used is

intended to be in the nature of words of description rather than of
limitation. Obviously, many modifications and variations of the
present invention are possible in light of the above teachings. It is
therefore to be understood that within the specification, the
reference numerals are merely for convenience, and are not to be in
any way limiting, the invention may be practiced otherwise than is
specifically described.

WE CLAIM:
1. A class H insulation system according to the present invention
comprising of:
a main insulation preferably silicone based glass mica aramid fibre
tape;
conductor insulation preferably fused corona resistant polyimide
insulation;
stack pressing material preferably class H varnish;
lead emerging point reinforcement preferably nomex left; and
other general and supporting materials in coil preferably polyimide
film or polyamide based materials.
2. The class H insulation system as claimed in claim 1, wherein
silicone resin especially for impregnating the windings of electrical
motors is applied by vacuum pressure impregnation.