Patent Application
20190372437
The present invention relates generally to a method for restoring a separation between laminations of a stator core of a generator.
A generator is a component in power generation industry that converts mechanical power to electrical power. A generator typically includes a stator and a rotor. A generator stator may employ a stator core comprised a plurality of axially extending slots along an internal circumference of the stator core. Stator windings are placed in the slots with insulation from the stator core. A rotor may be installed within the stator core.
A stator core may consist of a plurality of packs of stacked thin metal laminations. The laminations are insulated from each other by a very thin dielectric. The laminations direct magnetic flux around the stator core. If a number of laminations short together such that a loop can be established around the magnetic flux, then current will circulate in that loop generating heat. Shorting of laminations may occur very often due to foreign objects which may damage insulations between the laminations and smear the laminations together or may provide a path by connecting adjacent laminations with a conductive material. Other modes of lamination to lamination shorting may occur due to excessive heat from various sources affecting the dielectric coating. Damaged insulation of stator core may result in higher eddy current and a higher local temperature, also known as a local hot spot, between several laminations. The damage may spread out along the stator core over time and may cause damage of the generator.
To prevent current circulation within the stator core, a clear separation between the laminations needs to be restored. Typically, hand tools are used for restoring a clear separation between the laminations. The hand tools may include a small dental pick or similar to hand pick the attached laminations away and restore the clear separation between laminations. The hand tools tend to smear the laminations across their insulation boundaries. The process is also time consuming. There is a need to provide an easy and simple process for restoring a separation between laminations of a generator stator core.
Briefly described, aspects of the present invention relate to a method for restoring a separation between laminations of a stator core of a generator, a stator core of a generator, and a method for servicing a stator core of a generator.
According to an aspect, a method for restoring a separation between laminations of a stator core of a generator is presented. The method comprises applying a wicking resin to an area where the laminations are in contact with each other. The method comprises applying an etching using an etching solution to the area where the laminations are in contact with each other until a separation between the laminations is restored. The laminations are separated from each other by an insulation layer disposed between the laminations. The wicking resin is configured to seal the insulation layer to prevent the etching solution from penetrating into the insulation layer and causing a detrimental effect on the insulation layer.
According to an aspect, a stator core of a generator is presented. The stator core comprises a plurality of laminations. The stator core comprises an insulation layer disposed between the laminations that is configured to separate the laminations from each other. The insulation layer is configured to be sealable by a wicking resin. The wicking resin is configured to enable applying an etching using an etching solution to an area where the laminations are in contact with each other for restoring a separation between the laminations. The wicking resin is configured to prevent the etching solution from penetrating into the insulation layer and causing a detrimental effect on the insulation layer.
According to an aspect, a method for servicing a stator core of a generator is presented. The stator core comprises a plurality of laminations. The method comprises performing a test to the stator core for detecting an area where the laminations are in contact with each other. The method comprises applying a wicking resin to the area where the laminations are in contact with each other. The method comprises applying an etching using an etching solution to the area where the laminations are in contact with each other until a separation between the laminations is restored. The laminations are separated from each other by an insulation layer disposed between the laminations. The wicking resin is configured to seal the insulation layer to prevent the etching solution from penetrating into the insulation layer and causing a detrimental effect on the insulation layer.
Various aspects and embodiments of the application as described above and hereinafter may not only be used in the combinations explicitly described, but also in other combinations. Modifications will occur to the skilled person upon reading and understanding of the description.
Exemplary embodiments of the application are explained in further detail with respect to the accompanying drawings. In the drawings:
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.
A detailed description related to aspects of the present invention is described hereafter with respect to the accompanying figures.
During generator operation, a portion of the insulation layer 240 may be damaged. A portion of the laminations 230 along the portion of the damaged insulation layer 240 may be in contact with each other which may result in circulating current within the stator core 210. The circulating current may damage the stator core 210 and the generator 100. A clear separation between the laminations 230 are required in the stator core 210 of the generator 100 for preventing the damage of the stator core 210 and the generator 100.
Etching is a process using an etching solution to cut into metal surface. The etching solution may include a strong acid. Etching is an effective and efficient process to restore a clear separation between the laminations 230. However, the etching solution may cause detrimental effects on the non-damaged insulation layers 240. For example, for insulation layers 240 using non-porous materials, the etching may achieve a clear separation between laminations 230 without detrimental effects on the non-damaged insulation layer 240. For insulation layers 240 using porous materials or insulation paper, the etching solution may soak into the non-damaged insulation layers 240 and thus cause detrimental effects on the non-damaged insulation layers 240.
To use etching to restore a clear separation between the laminations 230 without causing detrimental effects on the non-damaged insulation layers 240, a wicking resin may be applied to the area 250 where the laminations 230 are in contact with each other. The wicking resin penetrates the non-damaged insulation layer 240 between the laminations 230. The wicking resin thus seals the non-damaged insulation layer 240 between the laminations 230 and provides a coating to the non-damaged insulation layer 240. For insulation layer 240 using porous materials or insulation paper, the wicking resin soaks into the non-damaged insulation layer 240 and provides a coating to the non-damaged insulation layer 240. For insulation layer 240 using non-porous materials, the wicking resin enhances the non-damaged insulation layer 240 and provides a coating to the non-damaged insulation layer 240. The wicking resin may be applied by any suitable manners, such as by spray, or by brush, etc. The wicking resin may include any suitable wicking resins that may seal the non-damaged insulation layer 240 and prevent an etching solution from penetrating and causing detrimental effects on the non-damaged insulation layer 240 when using etching to restore a separation between the laminatiopns 230.
Etching using an etching solution may be applied to the area 250 where the laminations are in contact with each other after applying the wicking resin. The etching solution may cut away the area 250 where the laminations 230 are in contact with each other. The non-damaged insulation layer 240 is sealed by the wicking resin to prevent the etching solution from penetrating and causing detrimental effects on the non-damaged insulation layer 240. The etching may be applied by any suitable manners, such as by spray, or by brush, etc. The etching solution may include any suitable etching solutions that may be used by the etching to cut away the area 250 where the laminations 230 are in contact with each other. The etching is applied until a separation between the laminations 230 by the non-damaged insulation layer 240 is restored.
According to an aspect, the proposed method provides an easy process for restoring a separation between laminations 230 of a stator core 210 of a generator 100. The proposed method uses wicking resin to protect the insulation layer 240 disposed between the laminations 230. The insulation layer 240 may include any suitable materials, such as porous materials, non-porous materilas, or insulation paper. The wicking resin seals the insulation layer 240 and provides a coating to the insulatin layer 240. The coating of the insulation layer 240 prevents an etching solution from penetrating and causing detrimental effects on the insulation layer 240 when using the etching to restore a separation between the laminatiopns 230 of a stator core 210 of a generator 100. The proposed method provides significantly cost savings and significantly increase efficiency for maintenance of a generator 100. The proposed method significantly increases operation life of a generator 100.
Although various embodiments that incorporate the teachings of the present invention have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings. The invention is not limited in its application to the exemplary embodiment details of construction and the arrangement of components set forth in the description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
