Description
An interrupter unit for circuit breakers
5 The present invention rel-ates to circuit breakers, and more
particularly reLates to an interrupter unit for circuit
breakers.
Circuit breakers are mechanical switching devj-ces which make
and break current cj-rcuit and carry nominal as wel-l- as short
circuit current when in closed condition. Circuit breakers
are typically designed to operate in different voltage range,
viz. ultra high voltage, high voltage, medium voltage and l-ow
voltage. Further, circuit breakers are classified as live
tank circuit breaker and dead tank circuit breaker. In live
tank circuit breakers, enclosure which contains an interrupter
unj-t is at line potential while in dead tank circuit
breakers, enclosure is at earth potential.
An exemplary l-ive tank ci-rcuit breaker 100 is lllustrated in
FIG 1. The l-ive tank circuit breaker 100 consists of a high
voltage terminal 101, an operating mechanism 102r do interrupter
unit 106 housed in a jacket 108 (e.g., ait/gas tight
porcelain jacket), operating rod 110, and a post insul-ator
104. The J-nterrupter unj-t 105 comprises a first main contact
It2 connected to a high voltage terminal 101, contact laminations
!L4 arranged in the first main contact LlZ, a second
main contact 7!6, a second arc contact 118, a first .arc Contact
L2O, a guide pin t22, a fork 124 connected to the first
arc contact 720, pist.on L26, valve plate 128 and an insul-ating
member 130 connected to the second arc contact 118.
In the closed condition, the second arc contact 118 and the
first arc contact L20 forms a primary contact. Similarly, the
first main contact !!4 and the second main contact 116 form a
secondary contact. When the operating mechanism L02 receives
a command for open operation, the operating mechanism 702
puIIs the second arc contact 118 and the second main contact
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116 towards the l-eft hand side via a l-ink L32. Consequently,
the secondary contact is opened first while the primdr! con=
tact between the first arc L20 and the second arc contact 118
remains closed.
As thd second arc contact 118 is puIled further, the guide
pin L22 connected to the insulating member 130 moves towards
the left hand side and gets engaged with the fork L24, thereby
rotating the fork 1-24, connected to the first arc contact
!20, in a clockwise direction. The cl-ockwise rotation of the
fork 124 results in movement of the first arc contact 120 on
the right hand side. Accordingly, the primary contact between
the first arc contact L20 and the second arc contact 118
opens, thereby forming an arc. At the same time, the second'
main contact 116 moves towards t.he left hand side an'd compress
quenching gas (SEo or COz) between the piston !26 and
valve group. As a resul-t, the quenching gas is forced, in a
directio.n opposite to the movement of the piston 726 and the
valve plate L28, into the second main contact 116 and through
the gap between the second arc contact 118 and the arc
quenching'nozzLe L34, thus quenching the arc.
It is often desirabl-e that such circuit breakers meet high
requirements in terms of rel-iable opening and closing, consistent
quenching performance with rated and short-circuit
currents, and high performance, reliabl-e, maintenance free
operating mechanj-sms. However, in the existing interrupter
unit 106, a l-ot of wear and tear of mechanical components may
occur due to frequent engaging/disengaging of the mechanical
components such as the guide pin 722 and the fork L24 during
closing and opening operation.
In light of the foregoing, there is a need for an interrupter
unit which provides closing and opening and quick movement
with ease, and requires minimum maintenance.
It is therefore the object of the present invention to provide
an interrupter unit for circuit breakers which provides
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easy closing and opening and quick movement, and requires
minimum maintenance.
The above object of the present inventi-on is achieved by an
interrupter unit comprising a first contact unit connected to
a voltage .terminal and a second contact unit connected to an
operating mechanism. The first contact unit and the second
contact unit are in contact with each other during closed position
of the interrupter unit. Thus, during the closed condition,
current commutates from the first contact unit to the
second contact unj-t. In open condition, the first contact
unit is separated from the second contact unit. During closing
operation, the second contact unit is moved towards the
first'contact unit whereas the second contact unit is moved
away from the first contact unit during the opening operation.
The first contact unj-t is provided with a movable contact
component which is coupled to a drive unit. According to the
present invention, the drive unit comprises an elastic member,
a means for biasing the elastic element and a releasing
mechanism. The elastic member may be a spring including but
not l-imited to compression spring and helical spring. The
el-astic member is disposed about the movable contact component.
Therein, the el-astic member is positioned at the end of
the movabl-e contact component. One end of the elastic member
rests agai,nst a fixed member and other end of the el-astic
member rests agaJ-nst the end of the movabLe contact component.
The means of biasing the elastic member comprises an insulating
member. One end of the said means is connected to the releasing
mechanism and the other end of the said means is connected
to the second contact unit. The said means transfers
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the elastic member from uncompressed state to compressed
state and vice versa via the releasing mechanism during the
closing and opening operation of the interrupter unj-t respectively.
This is because said means is connected to the second
contact unit which is moved with respect to the first contact
unit during the closing and opening operation.
Due to the movement of said means, the releasing mechanism
j-nterlocks the biased el-astic member in the cl-osed position
of the interrupter unit and releases the interl-ocking of the
biased elastic member during the opening operation. The interloiking
of the biased el-astic member keeps the biased
el-astic member in the compressed state in the cl-osed posltion.
During the opening operation, release of the interlocking
of the biased elastic member transfers the biased elastic
member from the compressed state to the uncompressed state.
During the transfer from the compressed state to the uncompressed
state, the elastic member exerts a force on the movab1e
contact component which causes t.he movable contact component
to move in opposite direction with respect to the second
contact unit. Consequently, the movabl-e contact component is
separated from the second contact unit. Thus, the drive unit
provides quick and smooth operation of the movabl-e contact
component. ALso, wear and tear associated with the movement
of the movable contact component during opening and closing
operation is significantly reduced as compared to the interrupter
unit in the state of the art. Additionally, with the
usage of the elastic member, number of movi-ng component used
in the interrupter unit is reduced, thereby improving reliability
of the interrupter unit in addition to minima.l- maintenance.
Moreover, energy required by the operating mechanism
to move the movable contact component is minimal aS the movement
of.the movable contact component is provided by the
energy rel-eased by the compressed elastic member. The stroke
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on the movabl-e contact component is reduced as energy is
channelized into the elastic member during opening and closing
operation.
In some embodiments, the separation of the second contact
unit and the movable contact component is performed in a sy+-
chronized manner. For example, the separation of the second
contact unit and the movabl-e contact component may be synchronized
using an electronic control means such as actuating
switch or mechanical- control- means such a linkage. This faci-
Iitates movement of the second contact unit and the movable
contact component of the first contact unit with respect to
each other at a required speed and timing.
Therein, the releasing mechanism comprises a guiding member
with at l-east one guiding means in a longitudinal direction.
For example, the guiding means may be a groove or sl-.ot formed
on the guiding member. The guiding member is disposed about
the f irst arc contact. The rel-easing mechanj-sm f urther comprises
a mechanical- linkage connected to the guiding member
and the first arc contact. The mechanical Iinkage comprises a
sliding el-ement such as a ro1ler disposed in the guiding
means of the guiding member, and a connecting member with a
first end and a second end. The first end of the connecting
member is connected to the sliding element. The mechanical
linkage al-so comprises a first l-ever with a guiding means
such as a groove formed in an axial directj-on, wherein one
end of the first lever is connected to the second end of the
connecting member and other end of the first lever is hinged
at a fixed point. Eurthermore, the mechanical linkage comprises
a second lever having a first end and a second end and
hinged around a center point. The first end of the second
Iever comprises a sliding element such a roll-er disposed in a
vertical guiding means Such aS a groove in the first arc con-
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tact.. The second
ment disposed in
end of lever comprises a
the guiding means of the
second sliding elef
irst l-ever.
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The interrupter unit of the present invention can be employgd
in medium (1 to 72kV) as well as high voltage circuit breakers
(72.5kV or higher). Also, the interrupter unit can operate
at rated as well as short circuit current.
The above-menti-oned and other features of the invention wil-lnow
be addressed with reference to the accompanying drawings
of the present invention. The illustrated embodiments are intended
to illustrate, but not limit the invention.
The present invention is further described hereinafter with
reference to il-l-ustrated embodiments shown in the accompanying
drawj-ngs, in which:
FIG 1
FIG 2
25 FIG 3
FIG 4A
is a cross sectional view of
circuit breaker of the state
is a cross sectional view of
circuit breaker employing an
cording Lo an embodiment of
exemplary live tank
the art;
an exemplary live tank
interrupter unit acthe
present invention;
an
of
is a detailed view showing various components of
the interrupter unit according to an embodiment of
the present invention;
is a diagrammatic view of the interrupter unit of
FIG 3 in a cl-osed condition according to an embodiment
of the present invention;
is a diagrammatj-c view of the interrupter unit of
FIG 3 in an arc condition during opening operation
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FIG 48
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EIG 4C
according to an embodiment of the present
tion;
is a diagrammatic view of the interrupter
FIG 3 in an open position according to an
ment of the present invention; and
rnven-
,rr'ri-t of
embodi-
10
FIG 4D is a diagrammatic view of the interrupter unit of
FIG 3 in an arc position during closing operation
accordj-ng to an embodiment of the present j-nvention.
Various embodiments are described with reference to the drawings,
wherein like reference numerafs are used to refer the
drawings, wherein like reference numeraLs are used to refer
to like elements throughout. In the following description,
for the purpose of explanation, numerous specific details are
set forth in order to provide thorough understanding of one
or more embodiments. It may be evident that such embodiments
may be practiced without these specific details.
EIG 2 is a cross sectional- view of an exemplary lj-ve tank
circuit breaker 200 employj-ng an interrupter unit 202 according
to an embodiment of the present invention. The live tank
circuit breaker 200, which is a double interrupter unit
breaker, comprises two horizontal serially connected interrupter
units 202 which are at live voltage. Each of the interrupter
units 202 is adapted to interrupt current circuit.
Each of the interrupter units 202 is housed in the jacket
206. The jacket 206 is a hollow cylindrical housing made of
porcelain or polymeric composite material. Further, each of
the interrupter units 202 is operated to make or break current
circuit using the operat.ing mechanism 208. Both the in-
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terrupter units 202 are supported by the post insul-ator 2L0.
which insul-ates the interrupter units 202 from groun-d. The
post insulator 210 has one end at high voltage potential- and
other end at ground potential. The high voltage end of the
post ins'ul-ator 270 is mechanically coupled to the interrupter
units 202 by means of top mechanism house 212. The detailed
components of the interrupter unit 202 of EIG 2 are il-l-ustrated
in greater detail- in FIG 3.
Referring to EIG 3, the interrupter unit 202 in a closed condition
is depicted. The interrupter unit 202 incl-udes a first
contact unit 304, and a second contact unit 302. The. first
contact unit 304 mainly consists of a first main contact 3L2,
contact laminations 314, a first arc contact 316, and a drive
unit 322. The first main contact 3L2 is a stationary contact
component connected to the voltage terminal 204. The contact
Iaminations 314 are contact el-ements disposed on the inner
periphery -of the first main contact 372. The first arc contact
316 is a movable contact component which is coaxially
disposed with respect to the first main contact. 312. The
first arc contact 316 is coupled to the drive unit 322 which
facilitate movement of the first arc contact 316 along a l-ongitudinal-
direction durj-ng closing and opening operation. It
should be noted that the term 'coupled' referred herein means
The drive unj-t 322 comprises an el-astic member 320, an insulating
member 303 and a releasing mechanism 321. The elastic
member 320 may consist of a spring such as compression spring
or an extension spring. As depicted, the elastic member 320
is mounted coaxially on the first arc contact 3L6, whereby
one end of the elastic member 320 rests against a fixed member
348 and the other end of the elastic member 320 .rests
against the end of the first arc contact 316. Accordlng to
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the present invention, the elastic member 320 is adapted to
store ,elastj-c potenti-aI energy when the elastic member 320 is
compressed and release the stored energy to move the first
arc contact during the longitudinal direction during expansion
of the elastic member 320. For example, the el-astic member
320 is compressed during the closing operation of the interrupter
unit 202 and is released during the opening operation
of the interrupter unit 202.
1q The releasing mechanism 321 connects the end of the .first arc
contact 3L6, against which other end of the el-astic member
320 rests, and the means for biasing the el-astic member 320.
The releasing mechanism 321 consists of a guiding member 318
and a mechanical linkage 323 coupled to the guiding member
15 318 and the end of the first arc contact 316. The guiding
member 318 may be a cj-rcul-ar or rectangul-ar hol1ow member
wj-th one or more guiding means such as grooves formed in a
longitudinal direction. The guiding member 318 is disposed
about the first arc contact 316. The front end of the guidlng
20 member 318 is connected to a means 303 for biasing the efastic
member 320 as shown in FIG 3. In an exemplary implementation,
the means 303 for biasing the elastic member 320 comprises
an insul-ating member which prevents current to commutate
from the first contact unit 304 to the second contact
25 unit 302 in open condition in addition to biasing the elastic
member 320 via the releasing mechanism 321.
The mechanical- linkage 323 comprises at least one slider
crank mechanism whose one end is disposed 1n respective guiding
member 324 and other end is connected to the end of the
first arc contact 316. As shown, the i-nterrupter unit 202 employs
two slider-crank mechanisms, each on either side of the
guiding member 318. Each of the sl-ider crank mechanisms consist
of .a sliding el-ement 326, a connecting member 328, a
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first Iever 330, and a second lever 338. The first lever 330
comprises a guiding means 336 such as groove formed in an
axial direction and is hinged at point 334. The other end of
the first lever 330 is connected to the second end 332 of the
connecting member 328. The first end 331 of the connecting
member 328 is connected t.o the sliding element 326. The sliding
el-ement 326 is disposed in the guiding means 324. In o.:
exemplary implementation, the sliding element 326 comprises a
roller adapted to slide within the guiding means 324 during
opening and closing operation.
The second lever 338 consists of the first end and the second
end. The second lever 338 is hinged to a frame 342 around the
center point 344. The first end of the second lever 338 consists
of a sliding el-ement 341 which is disposed in a vertical
guiding means 343 at the end of the first arc contact 316..
The second end of the second lever 338 consists of a sliding
element 340 which is disposed in the guiding means 336 of the
first lever 330. The sliding elements 341 and 340 can be
rollers adapted to sl-ide within the guiding means 343 and 336
respectively during the opening and closing operation.
The second contact unit 302 mainly consists of a second arc
contact 306, a second main contact 308. The second arc contact
306 is connected to the operating mechanism 208 via an
operating rod (not shown) . The second main contact 308 is
disposed about the second arc contact 306. The second main
contact 308 and the second arc contact 306 are moved in a
longitudinal direction usi-ng the operating mechanisro 208 during
closing and opening operation to make or break the current
circuit.
During the closing operation, the first arc contact 316 and
the second arc contact 306 makes arcing contact couple fol,-
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lowed by the second main contact 308 making main contact
couple with the first main contact 3L2. The arcing contact
couple is achieved by moving the first arc contact 316 and
the second arc contact 306 towards each other in longitudinal
direction whereas the main contact couple is achieved by moving
the second main contact 308, along with the second arc
contact 306, towards the first maj-n contact 3L2 in longitudinal
direction. During the opening operation, the first main
contact 312 and the second main contact 308 are separated
first followed by separation of the first arc contact 316 and
the second arc contact 306. The separation of the arcing contact
is achieved by moving the first arc contact 316 and the
second arc contact 306 in opposite direction in a synchronized
manner. The movement of the second arc contact 306 is
achieved using the operating mechanism 208 while the movement
of the first arc contact 316 is achieved via the drive unit'
322 as explained in greater detail below'
The opening and closing operations of the interrupter unit
202 are illustrated in FIGs 4A to 4D. FIG 4A il-Iustrates the
interrupter unit 202 in a closed condition. Referring to FIG
4A, in the closed condition, current from the voltage termina}
204 commutates from the first main contact 312 to the
second main contact 308 and from the first arc contact 316 to
the second arc contact 306. It can be seen that, during the
closed conditi-on, the elastic member 320 disposed at the end
of the first arc contact 316 remains in compressed state.
Thus, in the compressed state, the elastic member 320 stores
elastic potential energy which can be used to move the first
arc contact 316 away from the second arc contact 306 during
opening operation.
when the operating mechanism 208 receives a command to open
the current circuj-t, the operating mechanism 208 pulls the
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second contact unit 302 towards a Left hand side via a link
(not shown). Due to this, the second arc contact 306 and the
second main contact 308 moves in a longitudinal direction towards
the left hand side. Consequently, the second main contact
308 is separated from the first main contact 312 and
hence the main contact couple is broken. However, the arcing
contact couple between the second arc contact 306 and the
first arc contact 316 remains intact. As a result, current
continue t,o commutate from the first arc contact 316 to the
second arc contact 306 as depicted in FIG 48.
As the second contact unit 302 is pulled to open the current
circuit, the insulating member 303 moves j-n a longitudinaldirectj-
on towards the left hand side. As a result, t-h. insulating
member 303 pulls the guiding member 318 towards the
l-eft hand side. Due to this, the guiding member 318 moves in
the dire.ction of the movement of the insul-ating member 303.
The movement of the guiding member 318 causes the sliding
member 326 to sl-ide inside the guiding means 324 in the direction
of movement of the guiding member 318. Due to this,
the first l-ever 330 turns in anticlockwise direction and the
sliding means 340 slides in the guiding means 336. At a certain
point, the sliding member 326 is locked against the
guiding means 324 due to the force exerted by the el-astic
member 320 on the end of the first arc contact 316.
As the insulating member 303 putls the gulding member 318
further,- the free end of the elastic member 320 begins to expand.
As a result, the elastic member 320 releases the stored
energy by _virtue of expansj-on, leading to movement of the
first arc contact 316 in longitudinal- direction towards the
right hand side, i.e., the direction opposite to the movement
of the second contact unit 302. Due to this, the sliding el-ement
341 sl-ides within the vertical guiding means 343 in the
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first arc contact 316. Consequently, the second lever 338 rotates
about the fixed hinge point 344 which j-n turn pauses
the first lever 330 to rotate in the anticlockwise direction
by virtue of the sliding motion of the sliding e1ement 340 of
the seco.nd lever 338 in the guiding means 335. Due to movement
of the first lever 330, the connecting member 328 moves
towards the l-eft hand side. Since there is no opposing force
for restricting the moment of the free end of the elastic
member 320, the stiding element 326 continues to move towards
the l-eft hand side followed by the movement of the guiding
element 318 by virtue of expansion of the elastj-c member 320 '
Due to this, the free end of the el-astic member 320 moves the
first arc contact 316 towards the teft hand side, L.e', the
direction opposite to the movement of the second arc contact
306. Consequently, the arcing contact couple between the
first arc contact 316 and the second arc contact 306 is separated
as ill-ustrated in EIG 4C'
on the other hand, when the operating mechanism 208 receives
a command to close the current circuit, the operating mechanism
208 pushes the second main contact 308 and the second arc
contact 306 in a longitudinal- direction towards the right
hand side. Due to t.his, the insulating member 303 and the
guiding member 318 moves in the longitudinal- direction towards
the right hand side. Consequently, the sliding member
326 siides in the guiding means 324 and the connecting member
32g moves towards the right hand side. Accordingly, the first
lever 330 rotates in the clockwise direction and the sliding
member 340 slides in the guiding means 336. This results in
rotation of the second lever 338 about the hinged point 344
in the anticl0ckwise direction which causes the first arc
contact 316 to move in the Iongitudinal direction towards the
Ieft hand side. simultaneously, the second arc contact 306
moves in the longitudinal- direction towards the right hand
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side as explained earlier. As a result, the first arc contact
316 and the second arc contact 306 makes an arcing contact
couple as depicted in EIG 4D. Due to this the current commutates
from the first arc contact 316 to the second arc contact
306. AIso, the movement of the first arc contact 316 towards
the -left hand side during the closing opelatj-on causes
the elastic member 320 to compress elastically. Due to the
compression, the elastj-c member 320 stores el-astic potential
energy during the closi-ng operation. ]t is understood that,
if the elastic member 320 is an extension spring, the elastic
member 320 to extend elastically during the closing ,oPeration,
thereby storing the elastic potential energy.
Further.movement of the second main contact 308 in the 10ngitudinal
direction towards the right hand side causes the
secondmaincontact30stomakeamaj.ncontactcouplewith
the first main contact 312 via the contact laminations 314 '
As are result, current commutates from the first main Contact
3t2tothesecondmaincontact30saSdepictedinElG4A.
when the main contact coupre is formed, the erastic member
320 is completely compressed due to which elastic potential '
energy is stored in the elastic member 320. Advantag-eousIy,
theelasticpotentialenergystoredintheelasticmember320
isutilizedforgeneratingcountermovementtothefirstarc
contact -316 and moving the mechanical linkage 32t independent}
yduringtheopeningoperationaSdescribedabove.
Although the present invention is described in greater detail
withrespecttothelivetankcircuitbreaker200,one
skilled in the art can envision that the interrupter unit 202
of the present invention can be employed in other type of
circuitbreakerssuchasdeadtankcircuitbreakers.Further,
it can be noted that the interrupter unit 202 according
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to the present invention can be used in medium voltage as
welI as high voltage circuit breakers.
1rrlhile the present invention has been described in detail with
reference.to certain embodiments, it should be appreciated
that the present invention is not limited to those embodiments.
In view of the present disclosure, many modifications
and variations woul-d be present themselves, to those skil-1ed
in the art without departing from the scope of the various
embodiments of the present invention, as described h'erein'
The scope of the present invention is, therefore, indicated
by the following claj-ms rather than by the foregoing description.
AIl changes, modifications, and variations coming within
the meaning and range of equivalency of the claims are to
be considered within their scoPe'
We Claim
1. An interrupter unit (202)
a first contact unit (304)
comprising:
connected to a voltage t.erminalclaim
3, wherein
guiding means
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(204); and
a second contact unit (302) connected to an operating mechanism
(208), wherein the first contact unit (304) is provided
with a movable contact component (316) which is coupled
to a drive unit (322), characterized j-n that the drive unit
(322) comprises:
an el-ast.ic member (320); and
a means (303) for biasing the elastic member (320).
2. The j-nterrupter unj-t (202) accordi-ng to claim 1, wherein
the drive unit (322) further comprises a rel-easing means
(321) which interl-ocks the biased el-astic member (320) in
closed position of the interrupter unit (202) and rel-eases
the interlocking of the biased elastic member (320) 'during
opening operatj-on of the interrupter unit (202) .
3. The interrupter unj-t (202) according to claim 2, wherein
the releasing means (327) comprises:
a guiding member (318) with at least one guiding means
(324) in a longitudinal direction, wherein the gulding member
(318) is disposed about the movable contact component (316);
and
a mechanj-cal linkage (323) connected to the guiding member
(318) and the movable contact component (316)
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4. The interrupter unit (202) according to
the mechanical linkage (323) comprises:
a sliding element (326) disposed in the
(324) ;
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L1
a connecting member (328) with a first end (331) and a
second end (332), the first end (331) of the connecting member
(328) is connected to the sliding element (326);
a first lever (330) with a guiding means (336) in an axial
direction, one end of the first lever (330) is connected to
the second end of the connecting member (328) and other end
of the first lever (330) is hinged at a fixed point (334);
and.
a second lever (338) having a first end and a second end
and. hinged around its center point (344), the first end of
the second lever (338) comprises a first sliding element
(343) disposed in a vertical guiding means (341) in the movab1e
contact component (316) and the second end of the second
Lever (338) comprises a second stiding element (340) disposed
in the guiding means (336) of the first ]ever (330).
5. The interrupter unit (202) according to claims t, wherein
the elastic member (320) is disposed about the movable contact
component (316).
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6. The interruPter
wherein one end of
fixed member (348)
rests against. the
unit (202) according to claim 1 or 5,
t.he elastic member (320) rests against a
and other end of the elastic member (316)
end of the movabl-e contact component (316)
7. The interrupter unit (2921 according to claim 1 or 2,
wherein the said means (303) comprises an insulating member'
8. The interrupter unit (202) according to cl-aim 7, wherein
one end'of said means (303) for is connected to the releasing
mechanism (321) and the other end of said means is connected
to the second contact unit (302).