CircuitBreaker ppt

8/9/2019 CircuitBreaker ppt

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C IRCUIT B REAKER


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WHAT IS A CIRCUIT BREAKER

• A circuit breaker is an equipment that breaks acircuit either manually or automatically underall conditions at no load, full load or shortcircuit.

• "the circuit breaker opens the circuit“ it is infact the electric-arc (arc for short) formedinside the circuit breaker, which interrupts thecircuit current.


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Operating PrincipleTwo contacts called electrode remains closedunder normal operatin conditions. !hen faultoccurs on any part of the system, the trip coil ofthe circuit breaker et ener i ed and contactsare separated.


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Arc Phenomenon

• An arc is struck when contacts are separated. Thecurrent is thus able to continue. Thus the main

duty of a circuit breaker is to distin uish the arc

within the shortest possible time.

• The arc pro#ides the low resistance path to the

current and the current in the circuit remainsuninterrupted.


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The arc resistance depends upon the

following factors. $e ree of ioni ation%en th of the arc&ross 'ection of the arc


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T YPES O F C IRCUIT

B REAKER

OIL

CIRCUIT

BREAKER

AIR BLAST

CIRCUIT

BREAKER

SF6

CIRCUIT

BREAKER

VACCUM

CIRCUIT

BREAKER


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Breaker Used In 132KV GridStation

• il &ircuit reaker

• *acuum &ircuit breaker • '+ &ircuit reaker


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Air

cushion

Bulk Oil Cir uit !reaker


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"o# Oil Cir uit Breaker

&onsists of two parts.

'upportin

&hamber.&ircuit- reakinchamber( consist

of fi ed andmo#in contact )


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$isad%anta&es O' Oil Cir uit Breaker

• t is inflammable and there is a risk of fire.• t may form an e plosi#e mi ture with air.•

t requires maintenance.• Absorbs moisture, so dielectric stren threduces.

• il leaka e problem.• il has to be replaced after some operations

because of the carboni ation of oil.


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Va uu( Cir uit Breaker

• *acuum is used as an arc quenchin medium.• /a#e reatest insulatin stren th.• 01 -2 to 01 -3 pressure is to be maintained.• 4sed in 005* panel in control room of rid

station.


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Va uu( Cir uit Breaker


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Ad%anta&es

• &ompact, reliable and ha#e lon er life.• 6o fire ha ards.•

6o eneration of as durin and afteroperation.• &an interrupt any fault current.

• 6o noise is produced while operatin .• 7equire less power for control operation.


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S)* Cir uit Breaker

0. 'ulphur /e afluoride ('+ ) as is used as an arcquenchin medium.

8. '+ is an electro-ne ati#e as.

9. t has stron tendency to absorb electrons.:. !hen contact are opened in a hi h pressure flow of'+ as, arc produced.

3. +ree electron in the arc are captured by the as.

. !hich build up enou h insulation stren th toe tin uish arc.2. it is much effecti#e for hi h power and hi h

#olta es ser#ices,


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Ad%anta&es

• 'imple construction, less cost.• '+ as is non flammable, non to ic ;

chemical inert as.• 'ame as is recirculated in the circuit.•


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Ad%anta&es O' S)* O%er Oil Cir uit Breakers

• 'hort arcin time• &an interrupt much lar er currents• >i#es noiseless operation due to its closed as circuit• 6o moisture problem• 6o risk of fire• 6o carbon deposits. 'o no trackin and insulation

problems• %ow maintenance cost


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Testing of circuit beake


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Ad%anta&es O' air !last O%er Oil Cir uitBreakers

• The risk of fire is diminished• The arcin time is #ery small due to rapid build up of

dielectric stren th between contacts• The arcin products are completely remo#ed by the

blast whereas oil deteriorates with successi#eoperations


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Testin& o' ir uit !reaker

testin is indispensable in order to assure whether or not a specific breaker will be able to withstand certain operatin conditions.

Type of test of circuit breaker (0) 'hort circuit test (a) $irect test

(b) ndirect test (8)'ynthetic test


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$ire t test and indire t test

• a circuit with only one power source to supplythe necessary current before interruption andthe necessary #olta e after interruption isknown as direct test.

• ndirect test are those which demonstrate thecapabilities for application in three phase

rounded and un rounded system.


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S+nt,eti test

• a circuit in which the necessary current beforeinterruption and the #olta e after interruptionare put to ether by means of different powersources or throu h different paths of the testcircuit.


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Ad%anta&e o' s+nt,eti test

• The breaker can be tested for desired transientreco#ery #olta e.

• oth test current and test #olta e can beindependently #aried. This i#es fle ibility tothe test.

• !ith this method a breaker capacity (


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T/A65' A6? @4=7?

CircuitBreaker ppt

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