Analysis of an Accident involving the arc extinguishing chamber of a ZW32-12 Vacuum Circuit Breaker Têkilişina Serhêdan di Şopandinê de ya Kompartmena Şopandinê ya Vanî ya ZW32-12

ZW32 - 12 vakyum çalakê di şabakên distribûsyonê de yê zi di hatiyê. Lê, performansa ZW32 - 12 vakyum çalakê yên ji alîkarên din derdikin ê ve girêtir in. Qada ZW32 - 12 vakyum çalakê yên performansa yekêmê ya zêde û da heta dêyînê operasyonan veşartî bivînin ku heta dêyînê şabaka berkevin [1]. Çalakê vakyumî tişebera ZW32 - 12 performansa yekêmêya zêde û cihan û mînayê, û piçûka wekî û kelek e.

Lê, di operasyonê anîda, dikarin ser çarojî, qetina dema dema ya zêde û zêdetir bike, pirsgirkî operasyonan biguherînin. Tenha bi tevahî pêşkêşkirina tajribeyê operasyonî û bikaranîna xebatên îlmî û efektîve, pirsgirkî operasyonan ê ZW32 - 12 vakyum çalakê bi rêjiyê dikare bi rastî rezebînin û bihêlin. Analîzî îlmî ya çarojanên mirîvan ê ZW32 - 12 vakyum çalakê û bikaranîna xebatên nîşanî yên îmkanî efektîve rêzikên efektîv a rezebînin pirsgirkîyan ê çalakan vakyumî.

Rojek accidenta gumanî bû. Di operasyonê de, destpêkî phase B ê çalakê veşartî li ser zemin rezebîye, ku heta çalakê veşartî bihêlin, û hemî bikarhênerên li serendê çalakê veşartî rojekê ve birra dema dema veşartin. Li wê dema, tenha xebatên acilî dikarin bihêlin, ya ku çalakê vakyumî li serendê çalakê veşartî bihêlin, û hemî kablên li serendê guhurt û bendêrê çalakê veşartî virazibînin, û switch ek bihêlin di navenda du tarafên çalakê veşartî de, bi ku amadebikeşûna herî çima şabaka di dema dema de bihêle werin.

Çalakê veşartî ji sîlê rakiribû. Destpêkî resistansa izolyasyonê li ser zemin ê phase B ê bendêrê çalakê veşartî zero bû, lê resistansa izolyasyonê li ser zemin ê guhurtê çalakê veşartî (di navenda çalakê veşartî de) ji zero rast bû (di navenda çalakê veşartî de, her phase bi megger test kirin). Li ser vê şînan, hewce ye ku li serendê phase B ê çalakê veşartî çarojî zemin hêliye, û kableya guhurtê phase B normal bû. Vê çaroja li ser çarojî zemin ê bendêrê çalakê rezebîne.

Bi virazibîna û binîna çalakê, destpêkî harîreka diskojîna chamberê vakyumî phase B diskojîna rast bû. Di navenda diskojîna phase B supportê, destpêkî chamberê vakyumî sereket bû. Şertên parçeyên virazibînên chamberê vakyumî wanê: contactên hilbijartî û statîk chamberê vakyumî rast bû, bi hejmarên nekînên ser sirtî, lê sirtî black bû û depositên sootî thick bû. Her enda shielding cylinderê ji markên burnî rast bû, bi difference positionî 180° di circumferential direction de.

Markên burnî di shielding shieldê statîk de li ser markên burnî shielding cylinderê, û markên burnî di bellows û bellows protection cover moving-end de li ser markên burnî shielding cylinderê. Ceramic shell burnî di navendên du markên burnî de. Inner wall shielding cylinder black bû, û outer wall away from marks burnî color normal bû. Ji navendên ceramic shell remaining jî markên abnormal nehatiye. Guide sleeve soften û flow down bû. Flow severe di part corresponding to mark burnî moving-end de, û boiling phenomenon approximate bû. Guide sleeve solidified moving conductive rod li ser open position fix bû.

Re-resentation and Analysis of the Accident Phenomena

Li ser şînan state surface contactên moving û stationary chamberê vakyumî, show that contacts did not experience arc burning in atmospheric environment, û contacts should be in open state; inner wall surface shielding cylinder black bû, which is formed by action of arc û small amount air. Outer side shielding cylinder away from marks burnî no discoloration because not affected by arc, indicating that arc is local ablation; gaps on both sides between stationary-end grading ring chamberê vakyumî û stationary end shielding cylinder severely burned, indicating that arc burning occurred there; gaps on both sides between moving end shielding cylinder û protection cover behind moving-end contact chamberê vakyumî severely burned, indicating that arc burning occurred there.

Guide sleeve has melting û flowing marks, û flowing severe û has boiling phenomenon at same position as mark burnî moving-end, indicating that high temperature of arc had great impact on this area û lasted for certain period; solidified guide sleeve fixed moving conductive rod in open position, indicating that switch performed opening operation during fault û that switch was in open state after fault; contact surface has soot deposit, indicating that its temperature was low during arc duration û there was no arc burning on its surface in later stage of accident development. It also shows that switch was in open state in later stage of fault. Accident process should be as follows:

Before fault occurred, vacuum interrupter had leaked air for some reason. Although still had certain degree of vacuum, no longer met operating conditions of vacuum interrupter. When accident occurred, circuit breaker was in closing operating state, û contacts of interrupter were closed. When phase B line on load side of switch was grounded, switch tripped automatically.

Interrupters of phases A û C were in good condition û successfully completed breaking operation. Phase B interrupter, with vacuum degree that did not meet operating conditions, still managed to extinguish arc between contacts successfully because in three-phase neutral-ungrounded system, when two phases are broken, third phase must also be broken.

This also confirms that contact surface was intact, with no obvious ablation even at edges û corners. Arc combustion was not completely confined between two contacts û had certain degree of diffusion, resulting in blackening of inner wall of shielding cylinder. Since inside of interrupter was in low-vacuum state, vacuum insulation ability was extremely low. This led to breakdown û arcing between shielding cylinder û moving-end bellows protection cover under recovery voltage, û arc could not be controlled.

Shielding cylinder heated up severely, û its potential changed, causing breakdown (breakdown at weakest point) with stationary-end shielding cover û generating arc. Arc transferred from moving end to stationary end, forming current path from power supply to ground û sustaining arc combustion until upper-level switch of this switch tripped û arc extinguished. There was still certain degree of vacuum in vacuum interrupter, but no longer met operating conditions due to gas leakage for some reason before fault occurred.

When accident happened, circuit breaker was in closed-circuit operating state, with contacts of interrupter closed. When phase B line on load side of switch was grounded, switch tripped automatically. Interrupters of phases A û C were in good condition û successfully completed breaking operation. For phase B interrupter, although vacuum degree did not meet operating conditions, arc between contacts was still successfully extinguished.

This is because in three-phase neutral-ungrounded system, when two phases are broken, third phase will inevitably be broken as well. This also confirms that contact surface was intact, with no obvious ablation even at edges û corners. Arc combustion was not completely confined between two contacts û spread to some extent, causing inner wall of shielding cylinder to turn black. As interior of interrupter was in low-vacuum state, its vacuum insulation capacity was extremely low. This led to breakdown û arcing between shielding cylinder û moving-end bellows protection cover under recovery voltage, û arc could not be controlled.

Shielding cylinder heated up severely, û its potential changed, resulting in breakdown (at weakest point) with stationary-end shielding cover û generating arc. Arc transferred from moving end to stationary end, forming current path from power source to ground û sustaining arc combustion until upstream switch of this switch tripped û arc was extinguished.