Title of Invention	AN IMPROVED INSULATION AND A PROCESS FOR MAKING THEREOF
Abstract	An Improved Insulation and the process of making the same comprising of:- - a preliminary layer of special moisture resistant polyimide insulation followed by a layer of fibre glass insulation on the wire; - conductor wire with this insulation are wound with required no. of turn into complete coils; - the coils are impregnated with high temperature resistant insulating varnish by using VPI, vacuum pressure impregnation process; - a final layer of silicone conformal coating is provided on the coils.

Title of Invention

AN IMPROVED INSULATION AND A PROCESS FOR MAKING THEREOF

Abstract

An Improved Insulation and the process of making the same comprising of:- - a preliminary layer of special moisture resistant polyimide insulation followed by a layer of fibre glass insulation on the wire; - conductor wire with this insulation are wound with required no. of turn into complete coils; - the coils are impregnated with high temperature resistant insulating varnish by using VPI, vacuum pressure impregnation process; - a final layer of silicone conformal coating is provided on the coils.

Full Text	FIELD OF INVENTION: This invention relates to an improved insulation and a process for making the same for manufacturing high voltage AC or DC electrical coils suitable for operation in highly humid and polluted environment. BACKGROUND OF THE INVENTION The present requirement of mass rapid movement in metropolitan cities requires various modes of transports and the one that is being preferred world wide Is of electrical multiple unit or EMU locomotives employing 3 phase AC traction motors for efficient operation. The conversion of single phase overhead traction power to three phase requires high voltage electronic invertors and high voltage reactors or inductors to have smooth three phase sinusoidal AC voltage to drive the three phase traction motors. To have increased efficiency it requires that the total electrical equipment is made as low in weight as possible. The reactors or inductors are bulky and heavy electrical components and contribute significantly to the overall weight of the electrical equipment thus, a reduction in weight of these inductors makes possible substantial higher efficiency. Normally the inductors and reactors are made oil cooled alongwith the main traction transformer, due to the requirement of handling of large amount of power and operation at high voltage and inert atmosphere. To achieve reduced weight, while delivering the maximum output, the present invention describes an improved insulation that enables operation of inductors and reactors in air cooled environment resulting in significant reduction in weight and improvement of traction efficiency. z- OBJECTS OF THE INVENTION It is therefore, an object of the present invention to propose an improved insulation and a process of mal art. Another object of the present invention is to propose an improved insulation and a process of making the same which is electrically sufficient to withstand high voltage irrespective of operating temperature. A still another object of the present invention is to propose an improved insulation and a process of making the same which is water resistant. A further object of the present invention is to propose a process of making the same which reduces the weight of the insulator. DETAILED DESCRIPTION OF THE INVENTION The inductor and reactor coils can be made of various constructions, like colls wound in disc shape or spirally wound in cylindrical shape. The coil windings material employed can be copper/ aluminium depending up on the overall rating space requirement and user preference. To have lowest weight it is needed to have maximum possible current density in the winding without exceeding the insulation temperature. To achieve this it is also required that the insulation should be of suitable thickness so that it provides sufficient electrical insulation while allowing proper heat dissipation. Unlike oil cooled equipment, where the insulation is protected by sealed oil filled tank, when the windings are air cooled, the insulation is also required to be resistant to moisture and conductive layers of contamination that settle on the winding during operation. In the present invention all the above goals are achieved by using a layer of special moisture -3- resistant polyimide insulation, followed by a layer of fibre glass insulation on the winding wire. The special water resistant polyimide insulation is suitable for operating temperature of more than ZOQOC and is having a radial insulation thickness of 0.15mm. Combined with glass insulating layer, provided for mechanical protection of polyimide film, the total radial insulation thickness on the conducting wire is of only 0.2mm. This allows proper heat dissipation while providing sufficient electrical insulation. The conductor wires with this insulation are wound with required no. of turns into complete coils. After winding of coils these are assembled, with or without core, as per the design, and the same are impregnated with high temperature resistant insulating varnish by using VPI, vacuum pressure impregnation process. A further layer of silicone conformal coating is provided on the coils after vacuum pressure impregnation. The overall radial insulation layer thickness over the main electrically charged current carrying conductors, with the above process, is about 0.3mm to 0.35mm only. This insulation is electrically sufficient to withstand high voltage while limiting the desired operating temperature. The water resistant insulation makes the windings and the inductors or reactors suitable for continuous operation under most humid coastal conditions, having very high humidity of more than 95% to perpetual continuous precipitation. The windings remain intact, unaffected and impervious to corrosive effects of layers of moisture absorbing conductive insulation, which becomes highly conductive under high humid conditions, even after long service life. The overall design makes it possible to reduce the weight of heavy inductors and reactors resulting in efficient operation of the associated utilities. -4- An Improved Insulation and the process of making the same comprising of:- - a preliminary layer of special moisture resistant polyimide insulation followed by a layer of fibre glass insulation on the wire; - conductor wire with this insulation are wound with required no. of turn into complete coils; - the coils are impregnated with high temperature resistant insulating varnish by using VPI, vacuum pressure impregnation process; - a final layer of silicone conformal coating is provided on the coils.

Full Text

FIELD OF INVENTION:
This invention relates to an improved insulation and a process for making the same
for manufacturing high voltage AC or DC electrical coils suitable for operation in highly
humid and polluted environment.
BACKGROUND OF THE INVENTION
The present requirement of mass rapid movement in metropolitan cities requires
various modes of transports and the one that is being preferred world wide Is of
electrical multiple unit or EMU locomotives employing 3 phase AC traction motors for
efficient operation. The conversion of single phase overhead traction power to three
phase requires high voltage electronic invertors and high voltage reactors or inductors
to have smooth three phase sinusoidal AC voltage to drive the three phase traction
motors.
To have increased efficiency it requires that the total electrical equipment is made as
low in weight as possible. The reactors or inductors are bulky and heavy electrical
components and contribute significantly to the overall weight of the electrical
equipment thus, a reduction in weight of these inductors makes possible substantial
higher efficiency.
Normally the inductors and reactors are made oil cooled alongwith the main traction
transformer, due to the requirement of handling of large amount of power and
operation at high voltage and inert atmosphere. To achieve reduced weight, while
delivering the maximum output, the present invention describes an improved
insulation that enables operation of inductors and reactors in air cooled environment
resulting in significant reduction in weight and improvement of traction efficiency.
z-

OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose an improved insulation
and a process of mal art.
Another object of the present invention is to propose an improved insulation and a
process of making the same which is electrically sufficient to withstand high voltage
irrespective of operating temperature.
A still another object of the present invention is to propose an improved insulation
and a process of making the same which is water resistant.
A further object of the present invention is to propose a process of making the same
which reduces the weight of the insulator.
DETAILED DESCRIPTION OF THE INVENTION
The inductor and reactor coils can be made of various constructions, like colls wound
in disc shape or spirally wound in cylindrical shape. The coil windings material
employed can be copper/ aluminium depending up on the overall rating space
requirement and user preference.
To have lowest weight it is needed to have maximum possible current density in the
winding without exceeding the insulation temperature. To achieve this it is also
required that the insulation should be of suitable thickness so that it provides
sufficient electrical insulation while allowing proper heat dissipation. Unlike oil cooled
equipment, where the insulation is protected by sealed oil filled tank, when the
windings are air cooled, the insulation is also required to be resistant to moisture and
conductive layers of contamination that settle on the winding during operation. In the
present invention all the above goals are achieved by using a layer of special moisture
-3-

resistant polyimide insulation, followed by a layer of fibre glass insulation on the
winding wire.
The special water resistant polyimide insulation is suitable for operating temperature
of more than ZOQOC and is having a radial insulation thickness of 0.15mm. Combined
with glass insulating layer, provided for mechanical protection of polyimide film, the
total radial insulation thickness on the conducting wire is of only 0.2mm. This allows
proper heat dissipation while providing sufficient electrical insulation. The conductor
wires with this insulation are wound with required no. of turns into complete coils.
After winding of coils these are assembled, with or without core, as per the design,
and the same are impregnated with high temperature resistant insulating varnish by
using VPI, vacuum pressure impregnation process. A further layer of silicone
conformal coating is provided on the coils after vacuum pressure impregnation.
The overall radial insulation layer thickness over the main electrically charged current
carrying conductors, with the above process, is about 0.3mm to 0.35mm only. This
insulation is electrically sufficient to withstand high voltage while limiting the desired
operating temperature. The water resistant insulation makes the windings and the
inductors or reactors suitable for continuous operation under most humid coastal
conditions, having very high humidity of more than 95% to perpetual continuous
precipitation. The windings remain intact, unaffected and impervious to corrosive
effects of layers of moisture absorbing conductive insulation, which becomes highly
conductive under high humid conditions, even after long service life.
The overall design makes it possible to reduce the weight of heavy inductors and
reactors resulting in efficient operation of the associated utilities.
-4-

An Improved Insulation and the process of making the same comprising of:-
- a preliminary layer of special moisture resistant polyimide insulation
followed by a layer of fibre glass insulation on the wire;
- conductor wire with this insulation are wound with required no. of turn
into complete coils;
- the coils are impregnated with high temperature resistant insulating
varnish by using VPI, vacuum pressure impregnation process;
- a final layer of silicone conformal coating is provided on the coils.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=zsxT54TbqVT5gPVObjZ+0A==&loc=wDBSZCsAt7zoiVrqcFJsRw==

« Previous Patent

Next Patent »

Patent Number

269092

Indian Patent Application Number

569/KOL/2008

PG Journal Number

40/2015

Publication Date

02-Oct-2015

Grant Date

30-Sep-2015

Date of Filing

20-Mar-2008

Name of Patentee

BHARAT HEAVY ELECTRICALS LIMITED

Applicant Address

REGIONAL OPERATIONS DIVISION (ROD), PLOT NO: 9/1 DJBLOCK, 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA-700091 BHEL HOUSE, SIRI FORT, NEW DELHI- 110049

Inventors:

#	Inventor's Name	Inventor's Address
1	MR. RAJEEV AGARWAL	REGIONAL OPERATIONS DIVISION (ROD), PLOT NO: 9/1 DJBLOCK, 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA-700091 BHEL HOUSE, SIRI FORT, NEW DELHI- 110049
2	MR. RAJENDRA KUMAR MOHAPATRA	REGIONAL OPERATIONS DIVISION (ROD), PLOT NO: 9/1 DJBLOCK, 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA-700091 BHEL HOUSE, SIRI FORT, NEW DELHI- 110049

PCT International Classification Number

F16L59/14; F17C3/08; F17C13/00;F16L59/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA