U.S. patent application number 15/188287 was filed with the patent office on 2017-12-21 for electrically insulating composition used in conjunction with dynamoelectric machines.
This patent application is currently assigned to General Electric Company. The applicant listed for this patent is General Electric Company. Invention is credited to Stephen Frank Francese, Jessica Mary Powers, Jeffrey David Sheaffer, David John Wardell.
Application Number | 20170362485 15/188287 |
Document ID | / |
Family ID | 60661660 |
Filed Date | 2017-12-21 |
United States Patent
Application |
20170362485 |
Kind Code |
A1 |
Sheaffer; Jeffrey David ; et
al. |
December 21, 2017 |
ELECTRICALLY INSULATING COMPOSITION USED IN CONJUNCTION WITH
DYNAMOELECTRIC MACHINES
Abstract
An electrically insulating composition comprising about 25 to
about 55 percent by weight of filler materials, about 45 to about
75 percent by weight of resin. The percentages being selected such
that the total percentage of components does not exceed 100
percent. The composition has a thermal conductivity of about 0.2 to
about 1.3 W/m-K when measured at 130.degree. C.
Inventors: |
Sheaffer; Jeffrey David;
(Glenville, NY) ; Wardell; David John; (Ballston
Spa, NY) ; Powers; Jessica Mary; (Colonie, NY)
; Francese; Stephen Frank; (Malta, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
60661660 |
Appl. No.: |
15/188287 |
Filed: |
June 21, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08K 2003/385 20130101;
C09K 5/14 20130101; C08K 3/36 20130101; C08K 7/04 20130101; C08K
3/40 20130101; H02K 3/30 20130101; C08K 7/18 20130101 |
International
Class: |
C09K 5/14 20060101
C09K005/14; H02K 3/30 20060101 H02K003/30; H01B 3/42 20060101
H01B003/42 |
Claims
1. An electrically insulating composition comprising: about 25 to
about 55 percent by weight of filler materials, the filler
materials comprising about 15 to about 25 percent of silane-treated
glass, 0 to about 30 percent of boron nitride, and 0 to about 1.5
percent of silane-treated fumed silica; about 45 to about 75
percent by weight of Bisphenol A (BpA) resin; and wherein the
percentages being selected such that the total percentage of
components does not exceed 100 percent, and the composition having
a thermal conductivity of about 0.2 to about 1.3 W/m-K when
measured at 130.degree. C.
2-5. (canceled)
6. The composition of claim 1, the resin comprising: about 80
percent Bisphenol A (BpA) resin, and about 20 percent Bisphcnal
Bisphenol F (BpF) resin.
7. The composition of claim 1, the boron nitride comprising: about
80 percent spherical boron nitride, and about 20 percent flake
boron nitride.
8. The composition of claim 7, and the composition having a thermal
conductivity of about 0.64 W/m-K when measured at 130.degree.
C.
9. The composition of claim 1, further comprising a pigment to
color the composition.
10. The composition of claim 1, further comprising a catalytic
hardener and accelerator.
11. An electrically insulating composition to be used with a
catalytic hardener and accelerator, the composition comprising:
about 25 to about 55 percent by weight of filler materials, the
filler materials comprising: (a) about 15 to about 25 percent of
glass; (b) 0 to about 30 percent of boron nitride; (c) 0 to about
1.5 percent of fumed silica; about 45 to about 75 percent by weight
of resin, the resin comprising Bisphenol A (BpA) resin; and wherein
the percentages being selected such that the total percentage of
composition components does not exceed 100 percent, and the
composition having a thermal conductivity of about 0.2 to about 1.3
W/m-K when measured at 130.degree. C.
12. The composition of claim 11, the composition components
comprising: about 20 percent silane-treated glass; about 22.5
percent boron nitride; about 0 to 0.2 percent silane treated fumed
silica; about 0.1 percent pigment; and about 57.3 percent resin,
wherein the resin comprises the balance of components.
13. The composition of claim 12, the boron nitride comprising:
about 80 percent spherical boron nitride, and about 20 percent
flake boron nitride.
14. The composition of claim 13, the resin comprising: about 80
percent Bisphenol A (BpA) resin, and about 20 percent Bisphenol F
(BpF) resin.
15. The composition of claim 13, the composition having a thermal
conductivity of about 0.97 W/m-K when measured at 130.degree.
C.
16. The composition of claim 11, the composition components
comprising: about 25 percent silane-treated glass; about 15 percent
boron nitride; about 0.2 percent silane treated fumed silica; and
about 59.8 percent resin, wherein the resin comprises the balance
of components.
17. The composition of claim 16, the boron nitride comprising:
about 80 percent spherical boron nitride, and about 20 percent
flake boron nitride.
18. The composition of claim 17, the resin comprising: 80 percent
Bisphenol A (BpA) resin, and 20 percent Bisphenol F (BpF)
resin.
19. The composition of claim 17, the composition having a thermal
conductivity of about 0.64 W/m-K when measured at 130.degree.
C.
20. An electrically insulating composition to be used with a
catalytic hardener and accelerator, the composition adapted for
insulating generator components, the composition comprising: about
20 to 25 percent of silane-treated glass; about 15 to 22.5 percent
of boron nitride, the boron nitride comprising about 80 percent
spherical boron nitride and about 20 percent flake boron nitride;
about 0.2 percent of silane-treated fumed silica; about 0 to 0.5
percent pigment; resin comprising the balance, the resin comprising
Bisphenol A (BpA) resin; and wherein the percentages being selected
such that the total percentage of composition components does not
exceed 100 percent, and the composition having a thermal
conductivity of about 0.6 to about 1.0 W/m-K when measured at
130.degree. C.
21. An electrically insulating composition comprising: about 25 to
about 55 percent by weight of filler materials, the filler
materials comprising silane-treated glass, boron nitride, and
silane-treated fumed silica, the boron nitride comprising a mixture
of spherical boron nitride and flake boron nitride; about 45 to
about 75 percent by weight of Bisphenol A (BpA) resin; and wherein
the percentages being selected such that the total percentage of
components does not exceed 100 percent.
Description
BACKGROUND OF THE INVENTION
[0001] The composition described herein relates generally to an
electrically insulating composition for use with dynamoelectric
machines and, more specifically, to an insulating composition
having improved thermal conductivity.
[0002] Large or utility scale generators produce large amounts of
power, and also produce heat due to the large currents passing
through the conductors. Generators employ indirect or direct
cooling with air, hydrogen or water, depending on the amount of
power generated and the amount of cooling required. Specific areas
of the generator may benefit from additional electrical insulation
due to close proximity of neighboring generator components. Series
loops and phase leads connect the multiple stator loops together,
are external to the stator core and are in close proximity to each
other. One series loop may be at ground potential and an adjacent
series loop could be at full voltage potential. Therefore,
electrical insulation is placed over each series loop.
BRIEF DESCRIPTION OF THE INVENTION
[0003] In an aspect of the present invention, an electrically
insulating composition is about 25 to about 55 percent by weight of
filler materials, about 45 to about 75 percent by weight of resin.
The percentages being selected such that the total percentage of
components does not exceed 100 percent. The composition has a
thermal conductivity of about 0.2 to about 1.3 W/m-K when measured
at 130.degree. C.
[0004] In another aspect of the present invention, An electrically
insulating composition is to be used with a catalytic hardener and
accelerator. The composition has about 25 to about 55 percent by
weight of filler materials. The filler materials have about 15 to
about 25 percent of glass, 0 to about 30 percent of boron nitride
and 0 to about 1.5 percent of fumed silica. The composition also
has about 45 to about 75 percent by weight of resin. The resin is
Bisphenol A (BpA) resin. The percentages are selected such that the
total percentage of composition components does not exceed 100
percent. The composition has a thermal conductivity of about 0.2 to
about 1.3 W/m-K when measured at 130.degree. C.
[0005] In yet another aspect of the present invention, an
electrically insulating composition is to be used with a catalytic
hardener and accelerator, and the composition is adapted for
insulating generator components. The composition has about 20 to
about 25 percent of silane-treated glass, and about 15 to about
22.5 percent of boron nitride. The boron nitride is about 80
percent spherical boron nitride and about 20 percent flake boron
nitride. The composition also has about 0.2 percent of
silane-treated fumed silica, about 0 to 0.5 percent pigment, with
resin comprising the balance. The resin is a Bisphenol A (BpA)
resin. The percentages being selected such that the total
percentage of composition components does not exceed 100 percent,
and the composition has a thermal conductivity of about 0.6 to
about 1.0 W/m-K when measured at 130.degree. C.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a schematic diagram of ventilation flow
distribution in a forward flow generator.
[0007] FIG. 2 illustrates a cross-sectional view of a series loop
cap, having an electrically insulating composition encasing two end
windings.
[0008] FIG. 3 illustrates a cross-sectional top view along section
line 3-3 in FIG. 2 of a series loop cap that contains the
electrically insulating composition encasing two end windings,
according to an aspect of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0009] One or more specific aspects/embodiments of the present
invention will be described below. In an effort to provide a
concise description of these aspects/embodiments, all features of
an actual implementation may not be described in the specification.
It should be appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation-specific decisions must be made to achieve the
developers' specific goals, such as compliance with machine-related
and system-related constraints, which may vary from one
implementation to another. Moreover, it should be appreciated that
such a development effort might be complex and time consuming, but
would nevertheless be a routine undertaking of design, fabrication,
and manufacture for those of ordinary skill having the benefit of
this disclosure.
[0010] When introducing elements of various embodiments of the
present invention, the articles "a," "an," and "the" are intended
to mean that there are one or more of the elements. The terms
"comprising," "including," and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements. Any examples of operating parameters and/or
environmental conditions are not exclusive of other
parameters/conditions of the disclosed embodiments. Additionally,
it should be understood that references to "one embodiment", "one
aspect" or "an embodiment" or "an aspect" of the present invention
are not intended to be interpreted as excluding the existence of
additional embodiments or aspects that also incorporate the recited
features.
[0011] Cooling, ventilation and insulation are prime considerations
in the design of dynamoelectric machines, such as generator and
motors. Many of the benefits associated with improved reliability
and increased power capability can be traced directly to improved
thermal and insulation design. In a once-through ventilated
hydrogen-cooled generator, the cooling gas from the ventilating fan
is distributed into four branches: the gas gap between the rotor
and stator, the rotor subslot, the outside space block, and through
the end-winding (see FIG. 1). To cool the ends of armature
bars/coils near the series loop caps, the cooling gas passes
through the gap between the edges of armature bars/coils and the
tip of the gas shell. Thus, in order to achieve a relatively
uniform temperature distribution and to minimize ventilating
windage losses, the cooling flow path must be properly configured.
Series loop caps cover the joint between two end windings. The
series loop caps also insulate one series loop from a neighboring
series loop, as adjacent series loops may be at vastly different
voltages.
[0012] FIG. 2 illustrates a cross-sectional view of a series loop
cap 200 that contains an electrically insulating composition 210
encasing two end windings 222, 224, according to an aspect of the
present invention. FIG. 3 illustrates a cross-sectional top view
along section line 3-3 in FIG. 2 of a series loop cap 200 that
contains an electrically insulating composition 210 encasing two
end windings 222, 224, according to an aspect of the present
invention. The end windings 222, 224 may be brazed together to form
an electrical connection between the two end windings. The
electrically insulating composition 210, which may be in the form
of a putty when installed, encases and electrically insulates the
series loop connection of the end windings. The cap 200 serves as a
container for, or hard shell over, the electrically insulating
composition 210. The electrically insulating composition 210 has a
medium to high viscosity when installed, but then hardens to a
rigid and solid mass after curing. The resulting rigidity provides
structural support for inter-cap blocking. For example, rigid
blocks (not shown) may be placed between adjacent caps 200, and
then wrapped and frapped to secure the blocking. Therefore, the
electrically insulating composition 210 needs to be rigid and hard
to support the inter-cap blocking. The end windings 222, 224 have a
primary insulating layer 226 formed thereon, which is comprised of
multiple layers of paper, felt, glass fabric/tape and/or other
insulating layers. The electrically insulating composition 210
functions as a secondary insulation layer. However, the
electrically insulating composition 210 is also thermally
conductive to help transfer heat out of the windings 222, 224.
[0013] The electrically insulating composition 210 is comprised of
filler materials and a resin, and this will be used with a
catalytic hardener and accelerator (or any other suitable curing
agent). The filler materials may comprise about 25 to 55 percent by
weight of the composition, while the resin makes up the balance,
which is about 45 to 75 percent by weight. The electrically
insulating composition 210 will have a thermal conductivity of
about 0.2 to about 1.3 W/m-K when measured at 130.degree. C. These
levels of thermal conductivity will facilitate heat removal from
the end windings encased in the series loop caps.
[0014] The filler materials may include glass, boron nitride and
fumed silica. The glass is preferably silane-treated glass, and the
fumed silica is also preferably silane-treated. The silane
treatment is used to promote adhesion by creating a hydrophobic
surface, and it also improves the mechanical and workability
characteristics of the glass and silica. The fumed silica, which
may also be referred to as pyrogenic silica, is typically produced
in a flame and consists of microscopic droplets of amorphous silica
fused into branched, chainlike secondary particles which
agglomerate into tertiary particles. The resulting powder has a
very low bulk density and high surface area. The three dimensional
structure of the fumed silica results in a viscosity increasing,
thixotropic behavior when used as a thickener or filler.
[0015] Boron nitride is added to increase thermal conductivity. The
boron nitride may be a mix of spherical boron nitride or PTX60
(e.g., Momentive PTX60) and flake boron nitride or PT110 (e.g.,
Momentive PT110)). PTX60 and PT110 may be obtained from Momentive
Performance Materials Inc., Waterford, NY. Spherical boron nitride
or PTX60 is typically a powder having a spherical agglomerate
structure, mean particle size of about 55 to 65 micrometers, a
surface area of about 7 m.sup.2/gram, a tap density of about 0.4
g/cm.sup.3, an oxygen percent of about 0.3, carbon percent of about
0.05 and soluble borate percentage of about 0.1. Flake boron
nitride or PT110 typically has a single-crystal platelet or flake
structure, a mean particle size of about 45 micrometers, a surface
area of about 0.6 m.sup.2/gram, a tap density of about 0.7
g/cm.sup.3, an oxygen percent of about 0.3, carbon percent of about
0.03 and soluble borate percentage of about 0.05.
[0016] The resin may be a bisphenol A (BpA) resin, which is an
organic synthetic compound with a chemical formula (CH3)2C(C6H4OH)2
belonging to the group of diphenylmethane derivatives and
bisphenols with two hydroxyphenyl groups. The resin may also
include a bisphenol F (BpF) resin, which has a lower viscosity than
a BpA resin. The two types of resins may also be combined, for
example, the composition may have a mix of about 80 percent BpA
resin and about 20 percent BpF resin. Alternatively, a single resin
may be used (e.g., 100 percent BpA resin). In addition, a pigment
may also be added to the composition to differentiate different
mixtures by adding a specific color, (e.g., red, green, blue,
etc.).
[0017] As non-limiting examples only, some example electrically
insulating compositions will now be described. A first composition
may have about 15 to about 25 percent by weight of glass, 0 to
about 1.5 percent by weight of fumed silica and 0 to about 30
percent by weight of boron nitride, with the balance of the
percentage being resin. The total percentage will be equal to or
less than 100 percent. The glass and fumed silica is preferably
silane-treated. In this example the resin may be 100 percent BpA,
or a mixture of about 80 percent BpA and about 20 percent BpF. The
boron nitride may also be a mixture of about 80 percent spherical
boron nitride or PTX60 and about 20 percent flake boron nitride or
PT110. The term about, when referring to percentages, may be
defined as giving the stated values a tolerance of approximately
2.5 percent to 10 percent, or any subrange therebetween. An
optional pigment may also be added to this composition (e.g., about
0.1 to about 0.5 percent or more, depending on pigment
characteristics). The pigment percentage is primarily defined by
the desired color and intensity. The thermal conductivity of such
an electrically insulating composition will be about 0.2 to about
1.3, or 0.6 to 1.0, W/m-K when measured at 130.degree. C.
[0018] A second example for the electrically insulating composition
210 is, about 20 percent silane-treated glass, 0 to about 0.2
percent silane-treated fumed silica, about 22.5 percent boron
nitride, about 0.1 percent pigment and the balance being resin,
which in this case would be about 57.3 percent. In this example the
resin is 100 percent BpA, or a mixture of about 80 percent BpA and
about 20 percent BpF. The boron nitride is a mixture of about 80
percent spherical boron nitride or PTX60 and about 20 percent flake
boron nitride or PT110. The thermal conductivity of such an
electrically insulating composition is about 0.97 W/m-K when
measured at 130.degree. C.
[0019] A third example for the electrically insulating composition
210 is, about 25 percent silane-treated glass, about 0.2 percent
silane-treated fumed silica, about 15 percent boron nitride, and
the balance being resin, which in this case would be about 59.8
percent. In this example the resin is 100 percent BpA, or a mixture
of about 80 percent BpA and about 20 percent BpF. The boron nitride
is a mixture of about 80 percent spherical boron nitride or PTX60
and about 20 percent flake boron nitride or PT110. The thermal
conductivity of such an electrically insulating composition is
about 0.64 W/m-K when measured at 130.degree. C.
[0020] New electrically insulating compositions with high thermal
conductivity filler added have to have handling, application and
electrical, mechanical and thermal capability performances equal to
or better than present series loop capping compound materials.
Simply adding only a thermally conductive filler (e.g., boron
nitride) would not achieve the desired result as the desired
electrical and mechanical properties would be lacking. The present
invention uses a balance of materials to achieve the overall
properties mentioned above (e.g., mechanical, thermal, electrical,
etc.). Furthermore, the present invention may be used with bar to
bar connections, coil to coil connections, series loop connections
or joints between connection rings.
[0021] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *