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Study SF6Thermal Plasma generated
during/after power interruption
Final Project for Introduction to Plasma Processing
Instructor: Prof. Kasra temadi
ST!"#T:
$osny% &hmed &.
EE403/503, Fall 2005
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'utline
Introduction
Plasma characteristics
&d(antages and "isad(antages of SF6
)esidual SF6plasma species
*as Insulated Switchgear +*IS,
-onclusion
Future wor
)eferences
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hat is -ircuit 0reaer +-0,1
-0is one of the most essential
safety mechanisms in electric
networs.Interrupt short circuit currents
+2 63&% low pf 2 3.4,.Fault clearance time is (ery
important for power system
sta5ility and a(oid euipment
damage for itself and the rest of
the networ.-0can 5e characteri7ed 5y%
short circuit current% )ated
(oltage% 8
Figure 4: & schematic of -ircuit0reaer -onditions
Electric
Sub-
circuit
A
Circuit
Breaker
(CB)
ON/Off
Electric
Sub-
circuit
B
V,
V,
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Plasma lements8
++
+
+
+
+
+
+
+
!"ul#e V$lta%e,
&ra'#ie't ec$er*
V$lta%e (&V)
C$u"li'%
+a# ( SF)
Break$.'
a'!ae
la#!a#
E1ti'%ui#
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Figure 9: & plot shows plasma elements.
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Plasma Parameters8
eb*e e'%t
e
eD
n
T= 69 [m]
00 020 022 02406 00 02 04 0 06
05
02 04 0
04
0
3
02
0
00
0-
A)er
a%eElectr$'E'er%*,
7eV8
Electr$' Nu!ber e'#it*, 7c!-38
&er!$'uclear
la#!a#
Electr$'
Bea!
+l$.
i#car%eArc
i#car%e
S$li
9
+e'erat$r$'$#"ere
S$lar
C$r$'a
'ter#tellar
+a#
+a#e$u#Nebulae
5c
!
5!
5
!
5:
5'
!
5!!
P=100Hz
P=10KHz
P=1MHz
P=100MHz
P=10GHz
P=1THz
la#!a Fre;ue'c*
ep n= 97.8
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Plasma 8 Power Source
Transient )eco(ery oltage +T), T) is the (oltage that 5uilds up
across
a circuit 5reaer after the interruption of
a fault current.
It consists of oscillations of lumped
elements and of tra(eling wa(es. It stresses the circuit 5reaer
contacts
and depends on the type and location of
the fault in addition to the -0 it self.
Lc
tL
RttEe
tEidtcdt
di
LRi
r
1
cos2
expcos
cos
1
0
0
=
=
=++
Figure ;:+a, Single
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&rc ?uenching @echanism
Figure A: & Schematic representation of the puffer
interrupterindicating some important physical processes. =9>
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SF6has a dielectric strength of a5out two to three
times that of air.
It is nontoBic.
It is nonflamma5le.
It is noncorrosi(eC it doesnDt react with other
materials 5ecause it is inert gas. $owe(er% when it
is heated to E333- it decomposes and its
decomposition products react with other
materials.
It eBhi5its eBcellent properties for arc uenching.
So% it used as an interrupting medium in circuit
5reaers instead of air or oil.
Pros -ons of SF6
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SF6-ircuit 0reaer
Figure 6:SF6 -ircuit 5reaer%;6% A333&% S- E3&.
=49>Figure E: & plot of the thermal
conducti(ity of SF6and #9=44>
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)esidual SF6 Plasma Species
Ioni7ation
&ssociati(e detachment
"issociati(e attachment
eeSSe
eeFFe
+++
+++
+
+
eSFSF
eFFF
++
++
2
SFeSF
FFeF
++
++
2
Ta5le 4: Particle densities ofresidual SF6plasma at ;333 K%
43EPa =4>
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lectron elocity "istri5ution Function
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#ormali7ation Factor
nergy loss due to collisions-ollision freuency
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&d(antages of *as
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-onclusion
The primary -ause of high transient o(er
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Future or
Further study on calculation of T) and
post
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)eferences
4. H.". an% @.T.-. Fang and ?.S. Jiu% "ielectric 0readown of a
)esidualSF6 Plasma at ;333K under "iatomic uili5riumL% I
Transaction on
"ielectrics and lectrical Insulation% ol. A #o.4% Fe5ruary
4MMG.
9. ".. Shimmin and et al% Transient Pressure ariations in SF6
Puffer
-ircuit 5reaersL% &pplied Physics% 9; +4MM3, pp. E;;
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)eferences +-ont.,
G. )ichard @orrow% Theory of Positive Corona in SF6 %ue to a
&oltageImpulseL% I Transaction on Plasma Science% ol. 4M% #o.
9% &pril4MM4.
N. H. ". an% @. T. -. Fang and ?. S. Jiu% %ielectric Breakdown
of a'esidual SF6 Plasma at ())) * under %iatomic +,uili"riumL%
I
Transaction on "ielectrics and lectric Insulation% ol. A% #3.
4%Fe5ruary 4MMG.
M. *erd "uning and @anfred Jindmayer%L Plasma %ensity %ecay
of&acuum %ischarge After Current -eroL% I Transaction on
PlasmaScience% ol. 9G% #o. A% &ugust 4MMM.
43. @a7en &5del
