Misalaiya shi ne? | Misalaiya a Circuit Breaker

Idan an yi ƙarin bayani game da kawo arc ko kawo arc a cikin circuit breaker, ya kamata a tafi magana me kana da arc na ɗaya.

Me kana da Arc?

A lokacin da ɗalibai na ɗaya da ɗaya suka fadada a cikin circuit breaker, mutanen ɗaliban suka zama mai mahimmanci sosai saboda haka irin ɗaliba ta gida ta samu loko da ba ɗaya da ɗaya, kuma ɗaliba ta ci gaba a kan wannan loko hata a lokacin da ɗalibai suna fadada. A lokacin da ɗaliba ta haɗa daga ɗaya zuwa ɗaya, loko ta zama mai karfi saboda ɗaliba ta. Wannan shine ina jin arc.

Arc a Cikin Circuit Breaker

Idan ɗalibai na ɗaya da ɗaya suka fadada, akwai arc a cikin circuit breaker, wanda ya faru a kan ɗalibai masu fadada.

Duk da lokacin da arc ya faru a kan ɗalibai, ɗaliba ta ci gaba a cikin circuit breaker saboda arc yana da loko mai ɗaliba. Don haka don ɗaliban ta ƙare, ya kamata a kawo arc a gaba a gaba. Binciken mafi muhimmanci a cikin circuit breaker shine ya ba da tattalin kawo arc a cikin circuit breaker don ya ƙara ɗaliban da kuma ta ƙarfin ƙwarewa. Saboda haka, idan an yi ƙarin bayani game da tattalin kawo arc a cikin circuit breaker, ya kamata a tafi magana me kana da arc da kuma addinin arc a cikin circuit breaker, binkan ɗaya.

Ionization na Gas da Tsarki

Akwai elektron da ƙungiyoyi masu gas a tsari saboda sinarai, rayuwar kosmiki, da kuma radioactivity na duniya. Elektron da ƙungiyoyi waɗanda ake ƙunshi suna fi yawa saboda haka ba za su iya ƙara ɗaliban. Mutanen gas suna haɗa da ƙananan a tsari. Ana samun cewa mutum mai tsari a temperature da 300oK (Tsari) suna haɗa da ƙananan da velocity na 500 mita/sabu da suka haɗa da mutanen ƙananan da suka ƙare 1010 ƙare/sabu.

Mutanen ƙananan waɗanda suka haɗa da ƙananan suna ƙare da ƙananan da suka haɗa da ƙananan, amma kinetic energy da mutanen ƙananan suka da ba su iya ƙare electron daga atom da suka haɗa da ƙananan. Idan temperature ya ƙare, air ya zama mai tsarki saboda haka velocity da mutanen ƙananan ya ƙare. Velocity mai ƙari yana nuna impact mai ƙari a lokacin da mutanen ƙananan suka ƙare. A lokacin da wannan, wasu mutanen ƙananan suna ƙare zuwa atom. Idan temperature na air ya ƙare, abubuwan atom suna laƙe valence electrons da suka ƙare gas da ion. Kafin gas ya ƙare da ion, yana iya ƙara ɗaliban saboda elektron da ke ƙunshi. Hakan yana nufin plasma. Wannan shine ionization na gas da tsarki.

Ionization saboda Electron Collision

Kamar yadda ake magana, akwai elektron da ƙungiyoyi masu gas da air, amma suna fi yawa saboda haka ba za su iya ƙara ɗaliban. Idan elektron da ke ƙunshi suna ƙare electric field, elektron suna haɗa zuwa points da ke da potential mai ƙari a field da suka ƙare velocity mai ƙari. Duka haka, elektron suna haɗa zuwa direction na electric field saboda high potential gradient. A lokacin da suka haɗa, elektron suna ƙare da atoms da molecules na air da gas da suka ƙare valance electrons daga orbit.

Ba a nan da elektron suka ƙare daga parent atoms, elektron suna haɗa zuwa direction na electric field saboda potential gradient. Elektron suna ƙare da atoms da suka ƙare elektron masu ƙaranci. Saboda hakan, number da elektron da ke ƙunshi ya ƙare saboda gas ya ƙara ɗaliban. Wannan shine ionization na gas saboda electron collision.

Deionization na Gas

Idan duka abubuwan da suke ƙare ionization na gas suka ƙare, gas ya ƙare zuwa neutral state saboda recombination da ƙungiyoyi da elektron. Proses na recombination shine deionization. A deionization da diffusion, negative ions ko elektron da ƙungiyoyi masu ƙari suna haɗa zuwa walls saboda concentration gradients da suka ƙare process na recombination.

Rolin da Arc Ya Yi a Cikin Circuit Breaker

Idan ɗalibai na ɗaya da ɗaya suka fadada, arc ta faru a kan contact gap saboda ɗaliba ta samu loko da ba ɗaya da ɗaya, saboda haka ba za su ƙare ɗaliban a bangaren lokacin. Saboda ba a nan da ƙarfin ɗaliban ba a yi ƙare, ba za su ƙare voltage mai ƙarami a system. Idan i shine ɗaliba da ke haɗa daga ɗalibai idan suka fadada, L shine system inductance, switching over voltage during opening of contacts, may be expressed as V = L.(di/dt) where di/dt rate of change of current with respect to time during opening of the contacts. In the case of alternating current arc is monetarily extinguished at every current zero. After crossing every current zero the media between separated contacts gets ionized again during next cycle of current and the arc in circuit breaker is reestablished. To make the interruption complete and successful, this re-ionization in between separated contacts to be prevented after a current zero.

Idan arc a cikin circuit breaker ba a yi a lokacin da ɗalibai suka fadada, za a ƙare ɗaliban a bangaren lokacin, wanda yake ƙara voltage mai ƙarami saboda insulation na system. Amma, arc ta ba da transition mai kyau da ƙari daga ɗaliban zuwa breaking states na ɗalibai.

Arc Interruption ko Arc Quenching ko Arc Extinction Theory

Characteristics na Arc Column

A tsari mai ƙari, charged particles a cikin gas suna haɗa da ƙananan, amma ba a nan da electric field, ba a yi net motion. Idan an yi electric field a cikin gas, charged particles suna ƙare drift velocity superimposed a cikin thermal motion. Drift velocity shine proportional zuwa voltage gradient na field da particle mobility. Particle mobility depends upon mass na particle, heavier particles, lower the mobility. Mobility ta depend upon mean free paths available a cikin gas. Duk da lokacin da particle ta ƙare, ta laƙe directed velocity kuma ya zama da ita a haɗa zuwa direction na electric field. Saboda haka, net mobility na particles ya ƙare. Idan pressure na gas ya ƙare, gas ya ƙare denser, saboda haka, gas molecules suna haɗa da ƙananan, saboda haka ƙare ta ƙari, wanda ya ƙare mobility. Total current by charged particles shine proportional zuwa mobility. Saboda haka, mobility na charged particles depends upon temperature, pressure na gas, da nature na gas. Again, mobility na gas particles determines degree ionization na gas.

Saboda haka, ionization process na gas depends upon nature na gas (heavier or lighter gas particles), pressure na gas, da temperature na gas. Kamar yadda ake magana, intensity na arc column depends upon presence na ionized media between separated electrical contacts, hence, special attention should be given in reducing ionization or increasing deionization of media between contacts. That is why the main designing feature of circuit breaker is to provide different pressure control methods, cooling methods for different arc media in between circuit breaker contacts.

Heat loss from an Arc

Heat loss from an arc in circuit breaker takes place through conduction, convection as well as radiation. In circuit breaker with plain break arc in oil, arc in chutes or narrow slots nearly all the heat loss due to conduction. In air blast circuit breaker or in breaker where a gas flow is present between the electrical contacts, the heat loss of arc plasma occurs due to convection process. At normal pressure the radiation is not a significant factor but at higher pressure the radiation may become a very important factor of heat dissipation from arc plasma. During opening of electrical contacts, the arc in circuit breaker is produced and it is extinguished at every zero crossing of the current and then it is again reestablished during next cycle. The final arc extinction or arc quenching in circuit breaker is achieved by rapid increase of the dielectric strength in the medium between the contacts so that reestablishment of arc after zero crossing cannot be possible. This rapid increase of dielectric strength in between circuit breaker contacts is achieved either by deionization of gas in the arc media or by replacing ionized gas by cool and fresh gas.
There are various deionization processes applied for arc extinction in circuit breaker, let us discussed in brief.

Deionization na Gas saboda Increasing Pressure

Idan pressure na arc path ya ƙare, density na ionized gas ya ƙare, wanda yana nufin, particles a cikin gas suna haɗa da ƙananan, saboda haka mean free path na particles ya ƙare. Wannan ya ƙare ƙaranci, kamar yadda ake magana, a lokacin ƙaranci, charged particles suka laƙe directed velocity along electric field kuma suka haɗa zuwa field. Yana iya ce overall mobility na charged particles ya ƙare, saboda haka voltage required to maintain the arc is increased. Another effect of the increased density of particles is a higher rate of deionization of gas due to the recombination of oppositely charged particles.

Deionization na Gas saboda Decreasing Temperature

Rate na ionization na gas depends upon intensity na ƙaranci a lokacin ƙaranci. Intensity na ƙaranci a lokacin ƙaranci depends upon velocity na random motions na particles. Random motion na particle da velocity ta ƙare da ƙare temperature na gas. Saboda haka, ita ce if temperature na gas ya ƙare, ionization process na gas ya ƙare, da kuma opposite statement is also true, that is if the temperature is decreased, the rate of ionization of gas is decreased means deionization of gas is increased. Therefore, more voltage required to maintain arc plasma with a decreased temperature. Finally, it can be said that the cooling effectively increases the resistance of the arc.
Different types of circuit breakers employ different cooling techniques which we will discuss later in the course of circuit breakers.

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