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METHOD FOR IMPREGNATION OF A MACHINE

IP.com Disclosure Number: IPCOM000249858D
Publication Date: 2017-Apr-19
Document File: 17 page(s) / 63K

Publishing Venue

The IP.com Prior Art Database

Abstract

The present invention relates to a A method for impregnation of a laminated stack (3) comprising a plurality of lamination sheets, wherein at least one cooling cavity (5) in the laminated stack is sealed from a liquid resin (19) during the impregnation, the method comprises; attaching an air vent tube (4) with a first end to the at least one cooling cavity, arranging a second end of the air vent tube above a resin surface level (9); locating the laminated stack in a vacuum pressure impregnation tank (2, 20); applying a vacuum in the vacuum pressure impregnation tank; submerging the laminated stack in resin, by injecting the liquid resin into the vacuum pressure impregnation tank, whereby an air pocket (10) forms above the resin surface level, avoiding the at least one cooling cavities (5) to be flooded with resin, as the air vent tube (4) ensures similar pressure in the air pocket (10) and in the at least one cooling cavity (5). The invention also relates to a laminated stack arranged to be impregnated according to the method and a laminated stack produced according to the method.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 11% of the total text.

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METHOD FOR IMPREGNATION OF A MACHINE

FIELD OF THE INVENTION

The present invention relates to a method for manufacturing a laminated

stator with cooling channels.5

BACKGROUND OF THE INVENTION

Electrical machines like transformers, motors and generators have a high

efficiency; however, the electrical losses reach levels that needs be

removed through appropriate methods. The life expectancy of the electrical

winding isolation strongly depends on temperature, an increase of the 10

temperature level by about 10 Kelvin results in a halving of the life

expectancy. As the winding resistance is temperature dependent, an

improvement of the cooling would lead to a decrease in the copper losses.

It is therefore important to make a generator suitable for internal liquid

cooling. The normal philosophy behind a generator design is to have 15

insulated copper windings inserted into a numerous amount of merged

metal sheets acting as either stator or rotor. In order to fixate the windings

to the metal lamination sheets and to achieve sufficient reliability of the

thermal and mechanical properties, the full assembly in many cases

undergoes Vacuum Pressure Impregnation (VPI). 20

The fundamental idea behind VPI is to secure that no unwanted

cavities/voids in the design are left after impregnation without being filled

with resin.

A problem occurs when intentionally placing ducts and channels in the

sheet structure, with the purpose of allowing liquid fluids to pass through 25

the construction. The reason for this problem is that the fundamental

behaviour of the VPI process is also to fill the intended liquid ducts with

resin and blocking the cooling fluids from passing through the system.

2 2

It is thus an objective to present a method for impregnation of a machine

wherein cooling ducts/cavities are not filled with resin during impregnation.

SUMMARY

This summary is provided to introduce a selection of concepts in a

simplified form that are further described below in the detailed description. 5

A first aspect relates to a method for impregnation of a laminated stack

comprising a plurality of lamination sheets, wherein at least one cooling

cavity in the laminated stack is sealed from a liquid resin during the

impregnation, the method comprises;

- attaching an air vent tube with a first end to the at least one cooling 10

cavity,

- arranging a second end of the air vent tube above a resin surface

level;

- locating the laminated stack in a vacuum pressure impregnation

tank;15

- applying a vacuum in the vacuum pressure impregnation tank;

- submerging the laminated stack in resin, by injecting the liquid resin

into the vacuum pressure impregnation tank, whereby an air pocket

forms above the resin surface level

- avoiding the at least one cooling cavities to be flooded with resin, as 20

the air vent tube ensures similar pressure in the air pocket and in the

at least one cooling cavity.

An advantage of the first aspect, is that it can be the driver that makes

internall...