Breaker sa Air Blast: Operasyon, mga Advantages, ug Mga Tipo

Ang breaker sa air blast gamit ang compressed air o gas isip medium sa pag-interrupt sa arc. Ang compressed air gitipon sa usa ka tank ug kapag kinahanglan, girelease kini pinaagi sa usa ka nozzle aron mobuo og high-velocity jet. Kini nga jet importante kaayo sa pag-extinguish sa arc nga mubo kon ang circuit breaker mogamit sa pag-interrupt sa electrical current.

Ang air blast circuit breakers kasagaran gigamit para sa indoor applications sa medium-high voltage range uban medium rupturing capacities. Kasagaran, sila ang appropriate para sa voltages hangtod sa 15 kV ug rupturing capacities nga 2500 MVA. Usa pa, kasagaran gigamit kini sa high-voltage outdoor switchyards para sa 220 kV lines.

Kon hain ang iba pang mga gas sama sa carbon dioxide, nitrogen, freon, o hydrogen mahimong gamiton isip arc-interrupting media, ang compressed air ang naging preferred choice alang sa gas blast circuit breakers. Adunay daghang compelling reasons para niini:

• Nitrogen: Ang iyang circuit-breaking capabilities comparable sa compressed air, walay significant advantage sa performance.

• Carbon Dioxide: Usa sa iyang major drawbacks mao ang difficulty sa pag-control sa iyang flow. Kini may tendensya mosulob sa valves ug uban pang narrow passages, nga makapadisrupt sa proper functioning sa circuit breaker.

• Freon: Kon hain adunay high dielectric strength ug excellent arc-extinguishing properties, pero adunay hefty price tag. Padayon pa, kon exposed sa arc, kini mag-disintegrate ngadto sa acid-forming elements, nga nagdala og risks sa equipment ug sa surrounding environment.

Ang air blast circuit breakers naghatag og daghang desirable features:

• High-Speed Operation: Sa dako nga interconnected electrical networks, importanto ang maintenance sa system stability. Ang air blast circuit breakers excel dinhi tungod sa extremely short time interval tali sa discharge sa triggering impulse ug ang separation sa contacts. Kini nga rapid response makatabang minimo ang impact sa faults sa overall electrical grid.

• Suitability for Frequent Operation: Hinungdan sa circuit breakers nga gamitang oil, mas rapido matubdan ug degrade kon repeated switching, ang air blast circuit breakers makasulti sa frequent operation. Ang wala na sa oil naghulagway og minimal wear and tear sa current-carrying contact surfaces. Pero essential gyud ang continuous ug sufficient supply sa compressed air kon expected ang frequent switching.

• Negligible Maintenance: Ang ability sa handle repeated switching kasinat-on translate sa reduced maintenance requirements. Kini nakapagtubag sa savings sa maintenance costs ug enhance usab ang reliability ug availability sa circuit breaker.

• Elimination of Fire Hazard: Tungod kay wala na sa oil ang air blast circuit breakers, ang risk sa fire nga associated sa oil-filled circuit breakers totally eliminated, making them a safer option sa electrical installations.

• Reduced Size: Ang rapid growth sa dielectric strength sa air blast circuit breakers allows for a much smaller final gap required for arc extinction. Kini nga compact design resulta sa smaller-sized devices, nga mas easy ma-integrate sa electrical systems ug occupy less space.

Principle sa Arc Extinction

Ang air blast circuit breaker dependent sa additional compressed air system aron mopasabot ug air sa air receiver. Kon ang circuit breaker nanginahanglan mohibalo, ang compressed air gidirekta sa arc extinction chamber. Kini nga high-pressure air nag-exert og force sa moving contacts, causing them to separate. Kon ang contacts mag-separate, ang air blast nag-sweep away sa ionized gas nga nabuo sa arc, effectively extinguishing it.

Ang arc typically extinguished within one or more cycles. Pasabot sa arc extinction, ang arc chamber filled with high-pressure air, nga makatabang prevent restrikes. Ang air blast circuit breakers fall under the category sa external extinguishing energy type. Ang energy used for quenching the arc derived from the high-pressure air, independent sa current being interrupted.

Types sa Air Blast Circuit Breakers

Tanang air blast circuit breakers operate sa principle sa separating their contacts sa arc-forming airflow created sa pag-open sa blast valve. Ang arc nga nabuo quick centered through a nozzle, where it is maintained at a fixed length ug subjected sa maximum force sa air flow. Based sa direction sa compressed air blast around the contacts, ang air blast circuit breakers can be classified into three types:

• Axial Blast Air Circuit Breaker: Sa kini nga tipo, ang air flow parallel sa arc, flowing longitudinally along its length. Ang axial blast air circuit breakers can be further categorized as single-blast o double-blast. Ang uban nga double-blast arrangements, kon ang air blast flows radially sa nozzle o sa space between the contacts, sometimes referred to as radial blast circuit breakers, despite the primary axial-flow design concept.

Ang fundamental structure ug operasyon sa air blast circuit breaker illustrated sa diagram above. Sa normal operating conditions, ang fixed ug moving contacts remain sa closed state, held together by the force exerted by springs. An air reservoir tank linked sa arc chamber pinaagi sa air valve. Kini nga valve activated sa triple impulse mechanism, kon triggers its opening kon fault o need to interrupt the current arises.

Kon fault occurs sa electrical system, ang tripping impulse serves as the catalyst for action. Kini nga impulse activates the air valve nga connects the air reservoir sa arcing chamber, causing it to open. As high-pressure air from the reservoir rushes into the arc chamber, it exerts a significant force on the moving contacts. Once the air pressure surpasses the resistance provided by the spring force that normally holds the contacts closed, the moving contacts begin to separate, initiating the process of interrupting the electrical current and extinguishing the arc.

Kon ang contacts separate due sa pressure sa high-velocity air, an arc forms between them. The air, flowing at a high speed axially along the length of the arc, effectively removes heat from the arc's periphery. As the current approaches zero, this continuous heat extraction causes the arc's diameter to shrink significantly. At the moment when the current reaches zero, the arc is successfully interrupted. Subsequently, fresh air, streaming through the nozzle, fills the space between the contacts. This flow of fresh air clears away the hot, ionized gases that were present in the contact space, rapidly restoring the dielectric strength between the contacts and preventing any potential re-ignition of the arc.

Cross Blast Air Circuit Breaker

Sa cross blast air circuit breaker, ang arc-extinguishing mechanism operates differently. Hini, ang arc blast directed perpendicular sa arc itself. Ang figure below provides a schematic illustration sa cross blast principle employed sa kini nga tipo sa circuit breaker. Kon ang moving contact arm actuated sa confined space, an arc generated. Immediately, a transverse blast sa air propels this arc towards the splitter plates. The splitter plates fragment the arc into smaller segments, dissipating its energy. Kini nga process effectively weakens the arc to the extent that, after the current passes through zero, it lacks the energy to restrike, ensuring the successful interruption sa electrical circuit.

Resistance Switching ug Drawbacks sa Air Blast Circuit Breakers

Resistance Switching

Typically, resistance switching isn't an absolute necessity sa air blast circuit breakers. Kon ang arc quenched, it inherently creates some resistance, which helps to regulate the transient restriking voltage. Pero kon additional resistance deemed beneficial for specific applications, it can be incorporated sa pag-connect sa resistor across the arc splitter section. Kini nga added resistance provides an extra layer of control over the voltage transient, enhancing the circuit breaker's performance under certain conditions.

Drawbacks sa Air Blast Circuit Breakers

Usa sa major limitations sa air blast circuit breakers mao ang strict requirement sa continuous supply sa compressed air sa precise pressure. Aron ensure kini nga availability, large-scale installations often needed, typically featuring two or more compressors. Maintaining kini nga complex compression plant no small task; it demands regular upkeep to keep the compressors running efficiently ug address any mechanical issues that may arise.

Moreover, air leakage sa pipe fittings persistent problem. Even minor leaks can gradually deplete the air pressure, compromising the circuit breaker's performance. Detecting ug rectifying these leaks can be time-consuming ug labor-intensive. These maintenance challenges, combined sa need sa sophisticated air supply system, contribute sa higher operational costs.

Kon compared sa oil or other types sa air-break circuit breakers, air blast circuit breakers particularly expensive for low-voltage applications. The extensive infrastructure required sa compressed air generation ug associated maintenance expenses make them less cost-effective sa scenarios where lower voltages involved, limiting their widespread use sa such contexts.