See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/322675479
Thermal Performance of The Contacts in Circuit Breakers
Conference Paper · January 2018
CITATIONS
READS
0
317
5 authors, including:
Mohammad Jazini
Tehran Regional Electric Company,Iran,Tehran
1 PUBLICATION 0 CITATIONS
SEE PROFILE
Some of the authors of this publication are also working on these related projects:
ARC AT CIRCUIT BREAKER View project
All content following this page was uploaded by Mohammad Jazini on 24 January 2018.
The user has requested enhancement of the downloaded file.
No. E-15-AAA-0000
Thermal Performance of The Contacts in Circuit
Breakers
Mohammad Jazini
S. M. Mousavi G.
Department of Planning and Research, Tehran Regional
Electricity Company (T.R.E.C), Ministry of Energy,
Tehran, Iran
mohammadjazini@gmail.com
Centre of Excellence for Railway, Iran University of
Science and Technology
Tehran, Iran
Gevork B. Gharehpetian
Department of Electrical Engineering, Amirkabir University
of Technology.
Department of Planning and Research, Tehran Regional
Electricity Company (T.R.E.C), Ministry of Energy,
Tehran, Iran
Mahdi Jazini
Tehran, Iran
Grptian@aut.ac.ir
Mohsen Jazini
Department of Planning and Research, TAVANIR Company, Ministry of Energy,
Tehran, Iran
basis of contacts materials in Circuit Breakers factories,
refineries, power plants, super distribution and transmission
Whereas the conventional alloys with large mesh are not the
characteristics required for such contacts, the various
substations as well as gas and oil installations are mostly
metallurgical methods should be provided the desired alloy
equipped with high tension power. However, charge
.Costs of production, a broad survey of the alloy was
increase and grid development bring some difficulties to the
performed. The results show that the use of Nano scale metal
use of these equipments which in turn make high tension
powders, all the properties required for high power switches to
power designers face more complicated challenges. [9].
provide an incredible boost. In order to achieve this study are
examples of alloys W-Cu is made under various metallurgical
and electrical tests were high and the results showed the
correctness of the theory Tungsten-copper has unique material
properties. A high level of temperature resistance is one of the
most important advantages of tungsten, while the copper
content increases the electrical and thermal conductivity. Show
the relationship between geometric characteristics of the melt
bead and the optical-acoustic emissions from arc flash during
melting in the switching process. The paper summarizes
results of measurements of remelting area geometry, thermal
efficiency and melting efficiency.
keywords Circuit
breaker;
breakdown; Nano-contact;
I.
plasma;
Arc;
electrical
INTRODUCTION
The Nano structures generally are worked longer and
very stronger in electrical devices[1], [2].The nano sructures
was built with the aim of providing Strength electrical
connections are used[3], [4]. The electrical contacts Play an
important role in Circuit Breakers and is very important in
power electirc and electronic[5], [6].The contacts in power
electric mainly affect circuit breaker. If the surface
temperature on electrical contact, exceeds the tolerate is
contacts would melt and eventually led to the explosion is
circuit breaker[7],[8].In order to increase the stability of the
Due to its wide spread, power grid is exposed to
numerous events, the worst of which is short-circuits and
error currents. The closest breaker to error has the
responsibility of error removal by cutting off the faulty part
of the grid immediately. A shorter cut-off time results in
protection and improvement of stability in grid electrical
installations and users power quality. As of yet, this
problem has received different solutions, each of which
involves some certain faults such as: cost increase in
construction and exploitation, increase in equipment
amounts, increase in place of installation, and so on. The
fact that smart grids establishment intensifies the
requirement of industries particularly electricity, oil and
energy industries to faster breakers, adds to the difficulty.
II.
THE IMPORTANCE OF REDUCING THE EFFECTS OF
ARC FLASH ON THE POWER CIRCUIT BREAKER
The negative effect of the electrical arc between the
circuit breaker power posts, the breaker substations are
close to error. Because the closer circuit breaker to the fault
location becomes more intense. Therefore, it should be
tougher to short circuit breaker remote substations and
provide relief in a shorter time. Therefore, should the
necessary calculations to determine the critical time and
time to fix the error by short-circuiting circuit breaker is that
in most cases, be carried out.
Paper Title
30th Power System Conference - 2015 Tehran, Iran
Therefore, taking into account the delay of the circuit
breaker off the arc flash, to be reached faster than the time
error handling is critical.
According to Table I if the generator is going to remain
stable, the error should be removed in an angle less than
critical one; otherwise, the generator will lose its stability.
Thus, as to jitter, the breaker function time should be less
than critical time for error removal so that system does not
lose its opportunity to reach stability. Generally, breaker
function time is the span between receive time of
telecommunication command to cut off and electrical
extinguishing. Moreover, this time should not be more than
two or three cycle (less than 60 seconds in 50(HZ)
frequency).
The review of the research team, on the events of recent
decades that cells containing circuit breakers for electricity
distribution and transmission posts, within the Tehran
Regional Electricity Company, did, it was found that 93%
of the events leading up to the arc flash and hit It had been
due to severe mechanical. Of this number, 72% in the arc
electrical due to an explosion just as circuit breakers and is
not suitable conductivity breaker blades, and increases the
critical time breaker performance resulting in the possibility
of problems and even explosion. The critical time is
increased because of the rise of the electrical arc. It is
essential to remember that critical time when to remain
stable power grid and global uncertainty it is necessary.
The circuit breaker is the only tool for switching electric
power supply networks can be used. Another important task
circuit breaker, cut area has a short circuit. Short circuit of
the electrical network in the area is said to electrical energy
in a way inappropriate, flow and if the circuit breaker is not
cut short. Electric energy in path, destroy electrical
equipment.
III.
THE FUNCTION OF HIGH VOLTAGE BREAKERS
In comparison to remote substation breakers, plant
substation breakers are more affected since they should
remove more intense short-circuits during a shorter time.
Therefore, it is necessary to calculate the enough critical
time to remove the error which is mostly a short-circuit
one[8].
Fig. 1 . The relationship between Arcing Gap (mm) and The length of
Arc(ms) About temperature arc flash in Fiders1 of Substation.
In all this time and heat tolerance electrical connection
should be enough so that the dough does not start and will
not end up melting.
Power plant breaker should operate within allowed
delay range Fig.1 at the error occurrence moment and
breaker function time should be less than tcr.
TABLE I. THE TIMING OF BREAKER FUNCTION AT ERROR MOMENT
tcr = receive + tarc
Sequence of events
tcr:
critical time of error removal.
receive: receive time of telecommunication command to cut
off from DCS and PMU devices .
tarc:
time delay from electric are extinguishing or
breaker function time.
1.
error time
2.
relay recognition
3.
sending cut-off command to breaker
4.
start and end of electrical arc flash
5.
breaker function
6.
allowed delay
7.
critical time
8.
generator instability
Thus, considering delay from electrical arc
extinguishing, breaker function should be faster than critical
time for error removal [9].
1
Fider is a kind of cell for feeding power grid that contains the circuit
breaker in the substation.
2
Paper Title
30th Power System Conference - 2015 Tehran, Iran
IV.
heat, for although Nano metals are small, they have more
stability [10].
ELECTRICAL ARC FLASH FEATURES
Electrical arc features are classified according to breaker
type and extinguishers inside the arc flash suffocating
chamber, shown at Table II.
4.
If conductivity of breaker s contacts is increased, the
electrical arc is more quickly established and finished. On
the other hand, since in Nano materials the contact area of
material is enhanced, the cross section to transfer power is
added, too. And it is known that because of skin effect,
electric current tends to flow on conductive areas.
TABLE II..ELECTRICAL ARC FEATURES IN KINDS OF CIRCUIT BREAKER
Electrical arc Feature
Arc Speed
Arc Time Period
6000 (m/s)
Oil circuit breaker with
quenching the arc flash by oil
10 ( s)
Gas circuit breaker (GIS) with
quenching the arc flash by SF6
gas and vacuum
0.4 ( s)
Air circuit breaker (AIS)
without quenching device
some seconds
Arc flashTemperature
20000
Nano Silver Alloys in circuit Breaker s Contacts
Since silver has the highest electrical and thermal
conductivity of all elements, it is the most common metal
used in construction of relay contacts, power circuit
breakers and conductorsz. Meantime, its high malleability
as well as its severe tendency to show reaction with Sulfur
and then production of Sulfide layer has made it the most
suitable cover for other metals and alloys[11].. Applying
silver in construction of gas circuit circuit breakers (GIS)
with arc flash extinguishing by SF6 gas is very productive,
for this gas is a combination of sulfur and fluorine, is 6
times heavier than air and its isolation property is 3 times
more than that of air [12], [13] .
In comparison between silver-copper alloy (Ag-Cu) and
silver-palladium alloy (Ag-Pd), copper is the most resistant
metal against corrosion. Moreover, cadmium in silvercadmium alloy (Ag-Cd) is an environmental pollutant for
which environmental limitations have been regarded.
Instead, silver-lithium-lanthanum alloy (Ag-Li-La) can be
replaced which has more properties, as well.
However, the usage of Nano silver would have positive
effects on improvement of following items:
1. The increase of cross section to transmit power
with faster pass of electrical arc because of higher
conductivity of Nano silver.
°C
Electrical arc suppressing is crucial for grid and
industrial installations; therefore, numerous technical
techniques have been suggested.
Electrical Arc Extinguishing Methods
These methods include [9]:
1. Lengthening the distance between two contacts.
2. Quenching the electrical arc by oil, gas and
vacuum.
3. Adding multiple electrical arc extinguishing
chambers.
4. Employing Nano metal alloys in breakers blades .
V.
USAGE OF NANO METALS IN IMPROVING THE
FUNCTION OF HIGH VOLTAGE BREAKERS.
Usage of Nano Metals duo to Improve the Function of High
Voltage Breakers.there are several solousion for this.
1.
Reducing the extinguishing time of electrical arc:
2.
The increase of electrical arc heat transmission and
the decrease of arc flash period by cooling it faster
[14], [15].
Cooling of equipments is of great importance, especially
in crucial places and underground spaces in urban, like:
common tunnel of energy installations and gas lines (GIL)
[16].
Decreasing the distance between two contacts:
The distance between breakers blades (breakers which
cut off the grid and error current) and sectionners (breakers
which separate the grid without charge and error) can be
decreased by lessening the electrical arc length using Nano
alloys.
Nevertheless, regarding the usage of Nano metals the
attention should not be given to investment on cooling
methods of electric installations but it ought to be drawn to
not producing heat and electrical arc which is the sthece of
heat production [17], [18].
2.
Quenching the electrialc arc without any loss of oil,
gas and vacuum in breaker:
Each time an electrical arc is produced, the amount of oil,
gas or vacuum of the breaker is reduced, too. Decreasing the
electrical arc slows this process which in turn decreases the
reduction of electrical arc extinguishing materials[9].
VI.
EVALUATION OF THE EFFECT OF TEMPERATURE ON
THE ELECTRICAL ARC
Plasma conducts electricity. The arc creation cycle is
continuous as long as there is energy in the contact and
plasma maintain contact with the material being cut to
establish an electric circuit[19], [20].
3.
Preventing from contact corrosion:
Each on-and-off in breaker makes the contacts
corrosive, burns breaker s particles and increases its heat
which finally result in longer-period arc. Nano alloys
applied in breaker s contacts prevent from corrosion and
In general, arc contacts exhibit significantly less stability
than do filament lamps because the gas plasma is inherently
3
Paper Title
30th Power System Conference - 2015 Tehran, Iran
unstable and can be affected both by magnetic fields and
erosion of the contact tips[21].
Tungsten-copper has unique material properties. A high
level of temperature resistance is one of the most important
advantages of tungsten, while the copper content increases
the electrical and thermal conductivity.
Tungsten copper composites have been used in
manufacture of electric contact .The manufacturing method
of the W-Cu composite material thin board characterized by
mixing the end of copper powder, and tungsten powder, and
having the first process for thermal spraying of carrying out
powder production, and the second process of carrying out
plasma spray coating of the above-mentioned powder for
thermal spraying to a substrate, and forming a thin board in
the manufacturing method of a metal base composite
material[26]..
During plasma arcing, tungsten-copper powder is melted
in a plasma arc and then propelled at high speed against the
workpiece that is to be coated. In this way, it is possible to
deposit impermeable, adherent layers on tools and various
equipment components. When switching occurs, the Arcing
contacts and contacts have to withstand temporary
°
temperatures of more than 10,000 C. Fig .2.
That is a challenge that the tungsten-copper contacts can
easily rise to. Using back-casting techniques, we are able to
achieve particularly reliable tungsten-copper bonds. The
contacts ensure optimum heat transfer and are able to
withstand even the most extreme mechanical stresses[22]..
Considerable knowledge exists on processing tungsten
powders over a broad particle size range. Published data and
processing models have been combined for tungsten
powders ranging from 100 nm to 100 m to build a
response model for press-sinter processing. The model
predicts apparent density, green density, green strength,
sintered density, sintered grain size, and product properties
such as strength, hardness, and wear resistance. Green
strength is a term used to describe a molded or cast products
ability to withstand handling, mold ejection, and machining
before it is completely cured or hardened. This physical
characteristic is a critical criterion in the productivity levels
processes such as injection molding and powder
metallurgy[27].
The quicker cast or molded products can be removed or
ejected from the mold and handled the higher the process
turnover becomes. This process must not, of course, damage
or alter the finished product so a high green strength rating
in any product is a desirable characteristic. The mechanical
strength which a compacted powder must have in order to
withstand mechanical operations to which it is subjected
after pressing and before sintering, without damaging its
fine details and sharp edges [28]. Good green strength
values play a vital role in many areas including the
ceramics, thermoplastic, and metal powder molding
industries. Further, the model isolates several problems as
particle size decreases that will require changes in how
tungsten powders are handled, compacted, and sintered.
Maps of strength versus processing conditions are generated
from the model to direct future efforts toward improved
properties using Nanoscale tungsten powders. From these
findings, new opportunities become evident for press-sinter
consolidation of Nanoscale powders.
Fig.2.Temperature of Plasma Arcing Between Contacts in Circuit Breaker
VII.
EVALUATION OF THE EFFECT OFTHE ARC FLASH
PROCESS IN THE CIRCUIT BREAKER
In the arc flash process in the circuit breaker, the melt is
produced by the extreme heat of an electrical arc drawn
between an contact and the workpiece, or in some cases,
between two contact s. Melts are made with or without the
application of pressure and with or without filler metals.
The plasma is a state of matter consisting of
free electrons and ionized atomsinteracting with each other
with a high electromagnetic conduction and high energy
density, normally maintained by elevated temperatures over
°
30,000 C. In the center of this channel, there is a negatively
charged contact[23].. When applying electricity to the
negative contact and touch the tip of the metal, the
connection creates a circuit. A powerful arc is generated
between the contact and the metal. Fig.2.
Composite tungsten-copper mainly as electrical contact
materials in harsh working conditions such as currents and
high voltages in electrical arcs severe mechanical wear,
surface melting, and so locate Therefore, optimization of
physical properties - mechanical and longevity of these
composites in this study process powder metallurgy is used
for the preparation of Nano-contacts. Powder metallurgy
(PM) is a term covering a wide range of ways in which
materials or components are made from metal powders. PM
processes can avoid, or greatly reduce, the need to use metal
removal processes, thereby drastically reducing yield losses
in manufacture and often resulting in lower costs [29].
The SF6 gas that passes through the electrical arc at high
speeds, will ionize conforming a very hot plasma flow
°
directly at 6 km per second with over 16,000 C [24].
In plasma, the energy begins to break down the gas
molecules and the atoms which begin to separate from
their electrons, which move quickly and causing the
4
Paper Title
30th Power System Conference - 2015 Tehran, Iran
collision with other electrons and ions, releasing a vast
amounts of energy[25].
VIII.
TABLE III. THE APPLICATION OF ELECTRICAL CONTACTS ON THE
APPLICATION AND THE LEVEL OF HEAT TOLERANCE
Energy of Arcing
Arcing Flash
Mechanical
Ultrasonic
Friction
Explosion
Chemical
Radiant
Gas
Thermit
Laser beam
Electron beam
Electro slag
Resistance
Resistance spot
Fig. 3 shows the Position of the 400 (kV) Moving Contact in Circuit
Breaker.
Resistance butt
Gas tungsten arc
Plasma arc
Electrical Arc
Gas metal arc
Shielded metal arc
Submerged arc
Detailed descriptions of the various processes may be
found in, we like to have good images to show the
difference between the main contacts and the arcing
contacts. When a circuit breaker opens, the main contacts
should open partially first before the arcing contacts start to
open. There should be no arcing damage to the main
contacts because the arc interruption takes place between
the arcing contacts. Table III.
Fig . 4. The Arc position & Nano-contact
This protects the current carrying surfaces of the main
contacts so there is minimum contact resistance at the main
contacts. Good contact surface means no overheating. For
the same reason, when the circuit breaker closes, the arcing
contacts close first, suffering any arcing damage. After the
arcing contacts are closed, the main contacts close. All this
keeps the main contacts in good condition.
At the heart of the switching chamber, W-Cu arcing
contacts are exposed to extreme mechanical and thermal
°
stresses, with (temperatures 20,000 K) being reached during
arcing. The attached image shows the damage to the
stationary and movable arcing contacts and to the arc runner
that extends into the arc chutes to extend and divide the arc
until it is extinguished. The main contacts, the 16 curved
segments across the middle of the image, are in good shape.
No arcing damage what so ever. This image is from a
medium voltage air circuit breaker.
Contact the extreme mechanical and thermal stress
during switching voltage by the power circuit breaker. For a
fraction of a second, the temperature is Several thousand
degrees resulting from the arc, increases. Temperature of
electrical arc, will rise several thousand. Fig. 3.
IX.
FABRICATION OF W 20WT% CU COMPOSITE
NANOPOWDER
Fabrication of W Cu 20wt% composite Nanopowder
and sintered alloy with high thermal conductivity. Fig. 4.
Tungsten-copper (W-Cu) materials are used for arcing
contacts in circuit breakers for high and medium voltage
applications:
5
1.
The mechanical energy is used for producing
metallic bond in friction, ultrasonic and
explosion switching.
2.
The highest heat generation is at the positive
pole: The heat of the arc in the first place leads
Paper Title
30th Power System Conference - 2015 Tehran, Iran
to the melting of the metal. At the same time
the heat makes the gas better ionized;
conductivity is improved. In case of gas metal
arc switching and submerged arc switching the
arc starts with a simple short circuit. Some
momentary short-circuits lead to arcing. These
results in ionization of the gas that becomes
conductive and a switching arc can be formed.
Fig. 4. In this regard, heat and mechanical
damage due to abrasion possible profile and
localized high density arc simulation and
simulation point-to-point movement of the
movable contacts to the fixed contact, the
contact resistance variation is calculated.
3.
X.
The estimates also makes a major contribution
to faster and cheaper access to the arc contacts,
and an estimated remaining life of the power
circuit breaker can also make
Fig. 5 shows the effect of an electrical Contact point on the electrical arc
and heat distribution.
Whatever the angle of the contact tip increases, the level
of contacts increases and Surface contact with electrical arc
reduces and .in Fig.6, the greater angle has level 1 that And
causes the electrical arc is focused on the tip of contacts
then is eroding faster tip contacts on small part of tip. and
more heat-tolerant material will eventually be processed. As
a result, about level 7 to design the electrical connection is
more suitable because it is the minimum angle.
EVALUATION OF THE EFFECT OF THE ANGLE OF THE
TIP OF THE ELECTRICAL CONNECTION
sample A, well-known geometric deviation is the out of
line positioning of the pieces. It's commonly called highlow. The deviation is usually caused by the skills of the
melter. In addition, In Fig. 5 to demonstrate graphically how
the conical selection will affect the size of the melt bead and
the amount of penetration, below is a drawing that shows
typical representations of the electrical arc shape and
resultant melt profile for different conical. Table IV.
In case of gas metal. the electrical arc switching and
submerged arc switching the electrical arc starts with a
simple short circuit. Some momentary short-circuits lead to
electrical arcing. These results in ionization of the gas that
becomes conductive and a switching arc can be formed.
Table IV
Sharper Contacts
Nano-contacts
Easy electrical arc starting
Usually harder to start the
electrical arc
Handle less amperage
Handle more amperage
electrical
arc shape
Narrower electrical arc shape
Good electrical arc stability
Potential for more electrical
arc wander
Less melt penetration
Better melt penetration
Shorter contact life
Longer contact life
Wider
In Fig7 you see differences between angle of contacts
0
( ) in the melt also the effect of current intensity and
electrical arc scanning velocity on geometrical parameters
of remelting.
The Nanostructured W-20wt%Cu electrical contact
materials was prepared by mechanical alloying and hot
press sintering process.The hardness of Nanostructured WCu contact materials is higher than that of conventional WCu alloy, but the electric conductivity is similar.
a)
The electrical breakdown voltage of Nanostructured
W-Cu material does not depend on breakdown
numbers, showing an excellent electrical arc stability.
c) Nanostructured W-Cu material shows the characteristic
of spreading electrical arcs, which is of benefit to
electrical arc erosion.
d) Whatever The smaller the particle size of the metal
powder used in the electrical connection of electrical
contacts uniform heat distribution and faster and
negative effects of electrical arc is reduced.
6
Paper Title
30th Power System Conference - 2015 Tehran, Iran
XI.
[7]
Nano Today Journal. Map points to stable nanostructured metals.
Nano Today, Volume 7, Issue 6, December 2012, Pages 482-483.
[8] Longhua Guo, Joshua A. Jackman, Huang-Hao Yang, Peng Chen,
Nam-Joon Cho, Dong-Hwan Kim. Solvothermal synthesis of
metal nanocrystals and their applications. Nano Today, Volume
10, Issue 2, April 2015, Pages 213-239.
[9] Chunli Bai, Minghua Liu.Implantation of nanomaterials and
nanostructures on surface and their applications. Nano Today,
Volume 7, Issue 4, August 2012, Pages 258-281.
[1] Mohammad Jazini, S. M. Mousavi G., G. B. Gharehpetian and
Mohssen Rafie.Increasing of Contact Strength with Nano-materials in
Electrical Breakdown. 2nd Regional CIRED Conference and
Exhibition on Electricity Distribution, Tehran, Iran,
CONCLUSION
Power equipment design with technological approach
towards Nano materials and their application in power
industry remove many problems in the area of power and
energy. One of these equipments is circuit breaker, the very
cut-off circuit breakers in short-circuits and circuit breakers
of error currents. Nanotechnology is very productive
regarding oil and the contacts between two sides of the
breakers. Following items are improvements which can be
reached through this process:
1.
Considerable reduction in circuit breakers size.
2.
The increase of lifetime and the decrease of
protection and repair service (P.M.).
3.
Considerable saving in amount of power substation
installations.
4.
Considerable saving in place of power substation
construction.
[2]
[3]
[4]
Reaching reliability is of great significance for which
measurement should be carried out through simulators and
accuracy should be evaluated by experimental tests. Of
course, these two factors have to be accompanied by
considering the sensitivity of substations and passive
defense. Afterwards, these equipments can be utilized in
development of substations.
[5]
Applications of Nano metals improve the performance
of high voltage circuit breakers:
[8]
[6]
[7]
[19]
1. Reduce the destruction of circuit breaker contacts and
fixed by the electrical arc.
2. Homogeneous distribution of heat in surface contact.
[20]
3. Decentralization electrical arc on the tip of the electrical
contact.
In general, Nano thecnology is very useful for power
electric.
XII.
[21]
REFERENCES
[1]
Kui-Qing Penga, Xin Wanga, Li Lia, Ya Hua, Shuit-Tong Leeb.
Silicon nanowires for advanced energy conversion and storage.
Nano Today, Volume 8, Issue 1, February 2013, Pages 75 97
[2]
Nano Today Journal .Heating up at the point of contact. Nano Today,
[22]
[23]
Volume 2, Issue 3, June 2007, Page 55.
[3] Longhua Guo, Joshua A. Jackman, Huang-Hao Yang, Peng Chen,
Nam-Joon Cho, Dong-Hwan Kim. Solvothermal synthesis of
metal nanocrystals and their applications. Nano Today, Volume
10, Issue 2, April 2015, Pages 213-239.
[4] Wei Wang, Wentao Duan, Suzanne Ahmed, Thomas E. Mallouk,
Ayusman Sen. Small power: Autonomous nano- and micromotors
propelled by self-generated gradients. Nano Today, Volume 8,
Issue 5, October 2013, Pages 531-554.
[5] B. He, Y. Yang, M.F. Yuen, X.F. Chen, C.S. Lee, W.J. Zhang.
Vertical nanostructure arrays by plasma etching for applications in
biology, energy, and electronics. Nano Today, Volume 8, Issue 3,
June 2013, Pages 265-289.
[6] Hui Wu, Yi Cui. Designing nanostructured Si anodes for high energy
lithium ion batteries. Nano Today, Volume 7, Issue 5, October
2012, Pages 414-429.
[24]
[25]
[26]
7
G. Eason, B. Noble, and I.N. Sneddon.On certain integrals of
Lipschitz-Hankel type involving products of Bessel functions. Phil.
Trans. Roy. Soc. London, vol. A247, pp. 529-551, April 1955.
(references)
J. Clerk Maxwell, A Treatise on Electricity and Magnetism, 3rd ed.,
vol. 2. Oxford: Clarendon, 1892, pp.68-73.
I.S. Jacobs and C.P. Bean.Fine particles, thin films and exchange
anisotropy. in Magnetism, vol. III, G.T. Rado and H. Suhl, Eds. New
York: Academic, 1963, pp. 271-350.
Junbo.Electrical Breakdown Characteristic of Nanostructured WCu Contacts Materials. Abbrev., in press.
K. Elissa, Title of paper if known, unpublished.
WANG.
Y. Yorozu, M. Hirano, K. Oka, and Y. Tagawa.Electron spectroscopy
studies on magneto-optical media and plastic substrate
interface.IEEE Transl. J. Magn. Japan, vol. 2, pp. 740-741, August
1987 [Digests 9th Annual Conf. Magnetics Japan, p. 301, 1982].
M. Young, The Technical Writer s Handbook. Mill Valley, CA:
University Science, 1989.
L J Kecskes, M D Trexler, B R Klotz, et ol. Densification
and Structural Change of Mechanically Alloyed W-Cu Composites [ J ]. Metallurgical and Materials Transactions A,
2001, 32A (11) : 2885-2893
B Thomas, K V Walter, M Roland, K E Sacegr. On the Application of W/Cu Materials in the Fields of Power Engineering and Plasma Technology[ J ]. IEEE Transactions, 1991,14
(1):8-13
C S Xiong, Y H Xiong, H Zhu, T F Sun, et al. Synthesis
and Structural Studies of the Cu-W Alloys Prepared by Mechanical Alloying[J]. Nanostructured Materials, 1995,5(5) :
425.
J C Kim, S S Ryu, Y D Kim and I H Moon. Densificatiun
Behavior of Mechanically Alloyed W-Cu Composite Powders
by the Double Rearrangement Process[J]. Scripta Materialia,
1998,39(6) : 669
Jin-Chun Kim, Sung-soo Ryu and In-Hyung Moon. Nanostructural Characteristics mad Sintering Behavior of W-Cu
Composite Powder Prepared by Mechanical Alloying [ J ].
Jthenal of Advanced Materials, 1999,31(4) : 37-44
D Y Ying and D L Zhang. Effect of High Energy Ball Milling
on Solid State Reactions in A1-25at. % Ni Powders[ J]. Materials Science and Technology, 2001,17(7): 815-822
J C Kim and I H Moon. Sintering of Nanostructured W-Cu
Alloys Prepared by Mechanical Alloying [ J ]. Nanostructured
Materials, 1998,10(2) : 283
J Kaczmar. Effect of Production Engineering Parameters on
Structure and Proerties of Cu-W Composite Powders [ J].
Powder Metall, 1989,32(3) : 171
Paper Title
30th Power System Conference - 2015 Tehran, Iran
[27]
B Ding, Z Yang and X Wang. Influence of Microstructure on
Dielectric Strength of CuCr Contact Materials in a Vacuum
[J]. IEEE Trans. On CPMT, 1996,19(1): 76-91
[28] H Zhang, Z Yang and B J Ding. Characteristic of W-ThO2
Thennionic Cathode Activated with Nanoscale Oxide [ J ].
IEEE Trans. On CPT Part A,1999,22(3): 455-459
[27] Y Wang and B J Ding. The Preparation and Properties of Microcrystalline and Nanocrystalline CuCr Contact Materials[J].
IEEE Trans. On CPT Part A, 1999,22(3): 467-472
[28] http://encyclopedia2.thefreedictionary.com/green+strength
[29] https://en.wikipedia.org/wiki/Powder_metallurgy
8
This document was created with Win2PDF available at http://www.daneprairie.com.
The unregistered version of Win2PDF is for evaluation or non-commercial use only.
View publication stats