No. 15-E-AAA-0000
The Nano-Contacts in Improving the Performance
of Circuit Breakers
Mohammad Jazini
S. M. Mousavi G.
Department of Electrical Engineering, Damavand Branch,
Islamic Azad University(IAU)
Damavand, Iran
mohammadjazini@gmail.com
Centre of Excellence for Railway, Iran University of
Science and Technology
Tehran, Iran
sm_mousavi@iust.ac.ir
Gevork B. Gharehpetian
Department of Electrical Engineering, Amirkabir University of Technology.
Tehran, Iran
Grptian@aut.ac.ir
the main contacts because the arc interruption takes place
between the arcing contacts.
Abstract—Nowadays, Nanoengineers hope to use nanopowders
as the basis of building materials for Electrical equipment
factories, refineries, power plants, super distribution and
transmission substations as well as gas and oil installations are
mostly equipped with high tension power. However, charge
increase and grid development bring some difficulties to the
use of these equipments which in turn make high tension
power designers face more complicated challenges. 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.
However, reduction in breaker operation does not have to do
with its mechanical, pneumatical or hydraulical on-and-off
system but with not extinguishing an electric arc caused during
the separation of contacts in order to cut the electric current.
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.
Keywords—nanopowder; Arc ;electrical breakdown;
NANO Contact;
I.
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.
The arcing contacts are enclosed in something called an arc
chute that extends and separates the arc until it is
extinguished when the circuit breaker opens. When the arc
chutes are contaminated with dirt or high humidity or
interrupt very high loads or fault currents, the arc chutes
take a beating. Whether you’re talking about Square D
circuit breakers, Cutler Hammer circuit breakers, Siemens,
Westinghouse or GE General Electric circuit breakers,
molded case circuit breakers, power circuit breakers, or
medium voltage air circuit breakers, the function of the arc
chutes is the same, take a beating to protect the main
breakers.
MAINTENANCE TOOL DEVELOPMENT STRATEGY
When discussing circuit breakers, 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
Fig. 1.Electrical Contacts
The attached image shows the damage to the stationary
and movable arcing contacts and to the arc runner that
1
The Nano-Contacts in Improving the Performance of Circuit Breakers
The 3nd Nano Technology Conference in Power and Energy - 2015 Tehran, Iran
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.
Tungsten copper (WCu) materials are used for arcing
contacts in SF6 circuit breakers for high and medium
voltage applications:
At the heart of the switching chamber, WCu arcing contacts
are exposed to extreme mechanical and thermal stresses,
with (temperatures ≥ 20,000 K) being reached during
arcing.
Fig. 3 .The location of 400(kv) Contact in Curcuit Breaker
The arc erosion behavior of tungsten-copper is also
affected by the grain size of the tungsten, depending on
whether it is used as the cathode (C) or anode (A) and in an
SF6 or air atmosphere.Fig.1.

Fig. 4. The arc measurements of nano Contact with tester
Fig. 2. The arc erosion behavior of tungsten-copper
II.
Fig. 5 .The Cheking Rate of Short Circuits for Fider in Substation
WCu contact materials for use in vacuum.
a)Nanostructured W-20% Cu electrical contact materials was prepared by mechanical alloying and hot press
sintering process.The hardness of nanostructured W-Cu
contact materials is higher than that of conventional W-Cu
alloy, but the electric conductivity is similar.
b) The electrical breakdown voltage of nanostructured
W-Cu material does not depend on breakdown numbers,
showing an excellent electrical arc stability.
The nanostractured bulk of W-Cu contact material
was fabricated by hot press sintering in an electrical
vaccum furnace.The microstructure, electric conductivity,
hardness and break down voltage of NS W- Cu alloys
were measured and compared to those of conventional WCu alloys prepared by powder metallurgy.The experimental
results show that microstructural refinement and uniformity
can improve the breakdown behavior and the electric arc
stability of nanostractured W- Cu contacts materials. Also,
the nanostructured W-Cu contact material shows the
characteristic of spreading electric arcs, which is of benefit
to electric arc erosion.
c) Nanostructured W-Cu material shows the characteristic of spreading electric arcs, which is of benefit to
electrical arc erosion.
Error occurrence in one part of a power transmission
grid always leads to intensive disorders in other parts.
Hence, employing such intelligent devices as Smartgrid
Blackbox and breakers, and exploiting DCS and PMU
system, the smart power grid detects the fault condition with
a determined and calculated speed and finally separates it.
But, function optimization of circuit cut-off devices and
grid separators call for new and effective materials. This
article investigates the role of Nano technology in
development of short-circuit breakers and error occurrence
2
The Nano-Contacts in Improving the Performance of Circuit Breakers
The 3nd Nano Technology Conference in Power and Energy - 2015 Tehran, Iran
lose its opportunity to reach stability. Generally, breaker
function time is the span between receive time of
telecommunication command to cut off and electric arc
extinguishing. Moreover, this time should not be more than
two or three cycle (less than 60 seconds in HZ-50
frequency).
in power grid and emphasizes its effect on power grid
reliability and dynamic stability.
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. However, reduction
in breaker operation does not have to do with its
mechanical, pneumatical or hydraulical on-and-off system
but with not extinguishing an electric arc caused during the
separation of contacts in order to cut the electric current. 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.
III.
TABLE I.
Sequence of events
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].
IV.
THE TIMING OF BREAKER FUNCTION AT ERROR MOMENT
1.
error time
2.
relay recognition
3.
sending cut-off command to breaker
4.
start and end of electric arc
5.
breaker function
6.
allowed delay
7.
critical time
8.
generator instability
Thus, considering delay from electric arc extinguishing,
breaker function should be faster than critical time for error
removal[12].
V.
Electric Arc Features
Electric arc features are classified according to breaker
type and extinguishers inside the arc suffocating chamber,
shown at table 1.
Calculation of Electric Arc Effect on Function of
Substation Plant Breaker
TABLE II.
Since plant breakers should cut off more intense shortcircuit currents in a shorter time, they are considered as the
most intensive breakers in power grid. So, the produced
breakers should be measured and tested in their
manufacturing factory and their test results gained in the
high tension laboratory ought to be elicited as statistics in
order to obtain the required time for short-circuit removal
using the following formula. Finally, its effect on a
substation plant breaker connected to a generator can be
examined. Critical time for error removal can be calculated
by the below formula:
ELECTRIC ARC FEATURES
Electric Arc Feature
Arc Speed
Arc
Time
Period
Oil breaker with quenching the arc by oil
Gas breaker (GIS) with quenching the arc by
SF6 gas and vacuum
Air breaker (AIS) without quenching device
Arc Temperature
6000 (m/s)
10 (μs)
0.4 (μs)
some seconds
c
6000
Electric arc suppressing is crucial for grid and industrial
installations; therefore, numerous technical techniques have
been suggested.
Power plant breaker should operate within allowed
delay range (Fig. 4) at the error occurrence moment and
breaker function time should be less than tcr.
VI. Electric Arc Extinguishing Methods
These methods include [3]:
1. Lengthening the distance between two contacts.
2. Quenching the electric arc by oil, gas and vacuum.
3. Adding multiple electric arc extinguishing
chambers.
4. Employing Nano metal alloys in breakers’
blades[13].
tcr = treceive + tarc
tcr:
critical time of error removal.
treceive : receive time of telecommunication command to
cut off from DCS and PMU devices [1].
tarc:
time delay from electric are extinguishing or
breaker function time.
According to Fig. 4 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
VII. Usage of Nano Metals in Improving the Function of
High Voltage Breakers.
1.
3
Decreasing the distance between two contacts:
The Nano-Contacts in Improving the Performance of Circuit Breakers
The 3nd Nano Technology Conference in Power and Energy - 2015 Tehran, Iran
production of Sulfide layer has made it the most suitable
cover for other metals and alloys. Applying silver in
construction of gas breakers (GIS) with arc 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 [4], [10] .
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 electric arc length using Nano
alloys[14].
TABLE III.
Tungsten Nanopowder / Nanoparticles (W)
Purity: 99.95+% (metal basis)
APS: 40-60 nm
SSA: ~25 m2/g
Color: black
Morphology: spherical
Bulk Density: ~3.5 g/cm3
Nanoparticles True Density: 19.3 g/cm3
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 electric arc because of higher
conductivity of Nano silver.
2.
Quenching the electric arc without any loss of oil,
gas and vacuum in breaker:
Each time an electric arc is produced, the amount of oil, gas
or vacuum of the breaker is reduced, too. Decreasing the
electric arc slows this process which in turn decreases the
reduction of electric arc extinguishing materials.
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
heat, for although Nano metals are small, they have more
stability [2], [9].
4.
2.
The increase of electric arc heat transmission and
the decrease of arc period by cooling it faster[6],
[7].
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)
[9].
Reducing the extinguishing time of electric arc:
If conductivity of breaker’s contacts is increased, the
electric 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.

SILVER HIGH CONSUMPTION ALLOYS[11]
Nevertheless, regarding the
attention should not be given
methods of electric installations
not producing heat and electric
heat production.
Nano Silver Alloys in Breaker’s Contacts
usage of Nano metals the
to investment on cooling
but it ought to be drawn to
arc which is the source of
Conclusion
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 breakers and
conductors. Meantime, its high malleability as well as its
severe tendency to show reaction with Sulfur and then
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[15], [16]. One of these equipments is breaker, the
4
The Nano-Contacts in Improving the Performance of Circuit Breakers
The 3nd Nano Technology Conference in Power and Energy - 2015 Tehran, Iran
very cut-off keys 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.
2.
3.
4.
[10]
Considerable reduction in breakers’ size
The increase of lifetime and the decrease of
protection and repair service (P.M.)
Considerable saving in amount of power substation
installations[17].
Considerable saving in place of power substation
construction[18].
[11]
[12]
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. [19] Afterwards, these equipments can be utilized
in development of substations.
[13]
[14]
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[15]
Mohammad Jazini, S. M. Mousavi G., G. B. Gharehpetian and
Mohssen Rafie, "Increasing of Contact Strength with Nanomaterials in Electrical Breakdown", 2nd Regional CIRED
Conference and Exhibition on Electricity Distribution, Tehran, Iran,
[16]
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
W-Cu 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 Com-
[17]
[18]
[19]
5
posites [ 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 ].
Journal 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
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-$1
H Zhang, Z Yang and B J Ding. Characteristic of W-ThO2
Thennionic Cathode Activated with Nanoscale Oxide [ J ].
IEEE Trar~. On CPT Part A,1999,22(3): 455-459
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