LTB vs DTB vs GIS: Pagpili sa HV Circuit Breaker

Ang basic nga kahulugan sa usa ka high-voltage circuit breaker, simple ra gisulti, mao kini ang paggamit aron magbukas (interrupt, trip) ug magtutok (make, reclose) sa mga circuits, feeders, o partikular nga loads— sama sa mga konektado sa transformers o capacitor banks. Sa panahon sa fault sa power system, ang protective relays mogamit sa circuit breaker aron maputli ang load current o short-circuit current, pinaagi niining siguraduhon ang safe operation sa power system. 

Ang high-voltage circuit breaker mao ang usa ka tipo sa high-voltage switching device—mas dili kasagaran gitawag og “high-voltage switch”—ug usa sa key pieces of equipment sa substation. Apan, tungod sa stringent nga safety requirements sa high-voltage substations, ang mga personnel dili kasagaran makapasok sa substation aron makadako o fisikal nga makatouch sa mga devices. Sa daily life, kasagaran lang makita ang mga high-voltage transmission lines gikan sa layo ug dili kasagaran makakita o makatouch sa mga switches.

Pila man, unsa nga ang katuyuan nga hitsura sa usa ka high-voltage circuit breaker? Karon, atong ipailubon ang common classifications ug structural types sa circuit breakers. Hinumdumi sa low-voltage switches nga makita nato sa daily life—kasagaran gamiton ang air lamang isip arc-quenching medium—ang high-voltage circuit breakers nagkinahanglan og extremely high performance sa terms sa insulation ug arc interruption, kung diin kinahanglan special arc-quenching media aron masiguro ang electrical safety, insulation integrity, ug effective arc extinction. (Para sa daghan pang detalye bahin sa insulating media, pakisulay ang among upcoming articles.)

Duha ang main classification methods alang sa high-voltage circuit breakers:

1. Classification batas sa arc-quenching medium:

(1) Oil Circuit Breakers: Mas nahimong subdivided sa bulk-oil ug minimum-oil types. Sa duha, ang contacts magbukas ug magtutok sa oil, gamiton ang transformer oil isip arc-quenching medium. Tungod sa limited performance, ang mga tipos na mao naga-phase out na.

(2) SF₆ or Eco-friendly Gas Circuit Breakers: Gamiton ang sulfur hexafluoride (SF₆) o uban pang eco-friendly gases isip both insulating ug arc-quenching media.

(3) Vacuum Circuit Breakers: Ang contacts magbukas ug magtutok sa vacuum, diin ang arc extinction mahimo sa vacuum conditions.

(4) Solid-Quench Circuit Breakers: Gamiton ang solid arc-quenching materials nga mogamot sa high temperature sa arc, produci ng gas aron maputli ang arc.

(5) Compressed-Air Circuit Breakers: Gamiton ang high-pressure compressed air aron maputli ang arc.

(6) Magnetic-Blow Circuit Breakers: Gamiton ang magnetic field sa air aron i-drive ang arc sa arc chute, diin gi-stretch, gipalambo, ug maputli.

Karon, ang high-voltage circuit breakers primarily gamiton ang gases— sama sa SF₆ o eco-friendly alternatives—isip both insulation ug arc-quenching media. Sa medium-voltage range, ang vacuum circuit breakers dominant sa market. Ang vacuum technology gipadayon sa 66 kV ug 110 kV voltage levels, diin ang vacuum circuit breakers na gipalihok ug deployed.

2. Classification batas sa installation location:

Indoor-type ug outdoor-type.

Gidaghanon, batas sa insulation method relative sa ground, ang high-voltage circuit breakers mahimong icategorize sa tulo ka structural types:

1) Live-Tank Circuit Breaker (LTB):
Usa usab kini gigamiton og LTB. Sa definition, mao kini ang circuit breaker diin ang interrupter chamber adunay enclosure insulated from earth. Structurally, adunay post-type insulator design. Ang interrupter adunay high potential, enclosed sa porcelain o composite insulator, ug insulated from ground pinaagi sa support insulators.

Key advantages: Higher voltage ratings mahimo sa pagconnect sa multiple interrupter units in series ug pag-increase sa height sa support insulators. Kasagaran usab niya low-cost.

Equipment based on LTB forms Air-Insulated Switchgear (AIS), ug ang substations gihatag sa AIS gitawag og AIS substations. Kini offer low investment ug simple maintenance apan kinahanglan og large land areas ug frequent upkeep. Kini well-suited sa rural o mountainous regions diin abundant ang space, favorable ang environmental conditions, ug limited ang budgets.

2) Dead-Tank Circuit Breaker (DTB):
Usa usab kini gigamiton og DTB. Defined as a circuit breaker diin ang interrupter chamber adunay grounded metal tank. Ang conductive path led out through bushings.

Crucially, ang fundamental difference between LTB ug DTB mahimong matangganan sa grounding: sa DTB, ang tank adunay earth potential.

Advantages include the ability to integrate current transformers (CTs) directly onto the bushings, compact structure, significantly reduced footprint compared to LTB, better environmental resilience (suitable for harsh conditions), ug lower center of gravity—resulting in superior seismic performance. Ang primary disadvantage mao ang higher cost.

Switchgear based on DTB known as Hybrid Gas-Insulated Switchgear (HGIS), ug ang resulting substation gitawag og HGIS substation.

3) Fully Enclosed Combined Structure – Gas-Insulated Metal-Enclosed Switchgear, commonly referred to as GIS (Gas-Insulated Switchgear) sa high-voltage applications. Kini broadly covers such equipment. Ang circuit breaker component itself may also be specifically called a GCB (Gas-Insulated Circuit Breaker).

While similar sa DTB diin ang interrupter adunay enclosure, ang GIS different diin integrated not just the circuit breaker apan usab other essential substation components— including disconnectors, earthing switches, instrument transformers, surge arresters, ug busbars—all sealed within a grounded metal enclosure filled with pressurized SF₆ (or alternative insulating gas). Connections to external overhead lines made via bushings or dedicated gas compartments.

Substations built this way known as GIS substations (or Gas-Insulated Substations per IEE-Business standards). GIS ideal for urban areas diin expensive ang land, o for critical facilities like large hydropower or nuclear plants nga demand ultra-high reliability.

By now, clear na ang distinctions among high-voltage circuit breaker types—LTB, DTB, GCB—and the corresponding substation configurations—AIS, HGIS, GIS.