Vikabati vya Vakuum vs Vikabati vya Hewa: Tofauti Kuu

Tumia Circuit Breakers ya Mfumo wa Hewa chini ya Umbo la Kawaida vs. Circuit Breakers ya Vacuum: Muundo, Ufanisi na Matumizi

Circuit breakers ya mfumo wa hewa chini ya umbo la kawaida, ambayo pia inatafsiriwa kama circuit breakers za mfululizo au za mwamba (MCCBs), zimeundwa kwa majukumu ya umbo la AC 380/690V na DC hadi 1500V, na mafanikio ya umbo unaoweza kuwa kutoka 400A hadi 6300A au hata 7500A. Circuit breakers hizi hutumia hewa kama medium ya kupinda mkondo. Mkondo unapindika kupitia uzalishaji, upunguzi, na uchoma kwa arc chute (arc runner). Circuit breakers hizi zinaweza kusababisha current za short-circuit za 50kA, 80kA, 100kA, au hadi 150kA.

Mashala Makuu na Fanya Kazi

• Mbinu ya Kufanya Kazi: Iliyoko mbele ya circuit breaker, inatoa ubora wa kasi kwa ajili ya separation na closure ya contacts. Haraka ya mzunguko wa contacts inasaidia kuongeza na kuchoma mkondo, kusaidia kupinda.

• Kitengo cha Trip Chanya: Kilichoungwa pembeni ya mbinu ya kufanya kazi, ni "akili" ya circuit breaker wa umbo la chini. Inapokea signals za umbo na voltage kupitia sensors, huhesabu paramaters za umeme, na huilianza na mapema za protection za LSIG:

• L: Delay wa muda mrefu (protection ya overload)

• S: Delay wa muda fupi (protection ya short-circuit)

• I: Instantaneous (trip instant)

• G: Protection ya ground fault
  Kulingana na mapema hii, kitengo cha trip chanya hutoa ishara kwa mbinu ya kufunga circuit breaker wakati wa overloads au short circuits, kutoa protection kamili.

• Arc Chamber na Terminals: Iliyoko nyuma, arc chamber ina contacts na arc chute. Outgoing terminals za phase tatu chini zimezinduliwa na:

• Electronic current sensors (kwa ajili ya signal input kwenye kitengo cha trip chanya)

• Electromagnetic current transformers (CTs) (kutoa nguvu za kufanya kazi kwenye kitengo cha trip chanya)

Mbinu ya kufanya kazi mara nyingi ina umri wa kiwango chache tu wa 10,000 vipeo.

Maendeleo kutoka Hewa hadi Vacuum Interruption

Historically, medium-voltage air circuit breakers existed but were bulky, had limited breaking capacity, and produced significant arc flash (non-zero arc), making them unsafe and impractical.

Ingawa, vacuum circuit breakers (VCBs) yana muundo wa juu wa kawaida: mbinu ya kufanya kazi iko mbele, na interrupter iko nyuma. Lakini, interrupter hutumia vacuum interrupter (au "vacuum bottle"), ambayo ni structurally similar to an incandescent light bulb — a sealed glass or ceramic envelope evacuated to a high vacuum.

Katika vacuum:

• Gap ndogo tu ya contacts inahitajika kutoa maagizo ya insulation na withstand voltage.

• Mkondo unapindika haraka kwa sababu ya ukosefu wa ionizable medium na diffusion efficient ya metal vapor.

Matumizi ya Vacuum Circuit Breakers

Vacuum circuit breakers yamekuwa yanendelea haraka na sasa yamekuwa yamepandishwa sana katika systems za umbo la chini, medium, na juu:

• Low-Voltage VCBs: Mara nyingi rated at 1.14kV, na mafanikio ya umbo hadi 6300A na short-circuit breaking capacity hadi 100kA.

• Medium-Voltage VCBs: Zinazozingatwa zaidi katika range ya 3.6–40.5kV, na currents hadi 6300A na breaking capacity hadi 63kA. Over 95% of medium-voltage switchgear sasa hivi hutumia vacuum interruption.

• High-Voltage VCBs: Interrupters single-pole yamefika 252kV, na 550kV vacuum circuit breakers yamefikia kupitia interrupters za series-connected.

Tofauti Kubwa za Design

Kutokana na air circuit breakers ambazo hutumia contact springs, vacuum circuit breakers hutoa mbinu ya kufanya kazi:

• Kutoa ubora wa kasi wa opening na closing

• Kuhakikisha pressure ya contacts inapatikaniana

Pressure hii ya contacts inapaswa kuwa inapatikaniana hata baada ya wear ya contacts hadi 3mm, ili kurekebisha mafanikio ya umbo na kuweka mali ya peak short-time current wakati wa faults.

Faida za Vacuum Circuit Breakers

• Uaminifu na usalama wa juu

• Immuned kwa masharti ya mazingira (dust, humidity, altitude)

• Zero arc flash (no external arcing)

• Size ndogo na maintenance intervals mbalimbali

Faida hizi zinaweza kufanya vacuum breakers zisite bora kwa matumizi katika mazingira ya hatari kama vile plants za kimikia, coal mines, oil & gas facilities, ambako risks za explosion na usalama wa moto ni muhimu.

Case Study ya Dunia Halisi: Performance ya Vacuum vs. Air Breaker Under Fault

Chemical plant kubwa ilianzisha circuit breakers watano — moja air circuit breaker na moja vacuum circuit breaker — katika circuit configurations sawa na walipata same fault conditions.

Circuit ilikuwa tie configuration, ambayo power sources upande wa pili wa breaker walikuwa out of synchronization. Hii ilifanya transient voltage across the contact gap ikarudi mara mbili ya rated voltage, kusababisha failure ya breaker.

Matokeo:

• Air Circuit Breaker:
  Alipata destruction kamili. Enclosure ya unit ya breaker ilirupt, na adjacent switchgear upande wa pili alikuwa amebadilika sana. Reconstruction na replacement zilionekana.

• Vacuum Circuit Breaker:
  Failure ilikuwa duni sana. Baada ya kurudisha vacuum interrupter na kusafisha arc by-products (soot) kutoka breaker na compartment, switchgear ilirekebishwa kwa haraka.

Malizia

Vacuum circuit breakers huonyesha containment ya fault, usalama, na uaminifu wa juu kuliko air breakers, hasa under severe transient overvoltages. Interrupters zao za vacuum sealed zinapunguza propagation ya arc, kukidhibiti damage na downtime.

Katika mazingira ya explosive au flammable kama vile chemical plants na coal mines, operation ya arc-free na performance robust ya vacuum circuit breakers hunatoa advantage teknolojia na usalama.