Vacuum da Air Circuit Breakers: Muhimman Farko

Babban Farko da Kafin Kirkiya na Kirkiya mai Aira ta Tsakiyar Zafi a Filayu na Kirkiya mai Vacuum: Kudanci, Nauyin Yadda Ake Amfani Da Su

Kirkiyoyi mai aira ta tsakiyar zafi, ko kuma kirkiyoyi mai karfi ko molded frame circuit breakers (MCCBs), suna gina don voltages na AC daga 380/690V zuwa DC voltages zuwa 1500V, tare da currents na rating daga 400A zuwa 6300A ko hatta 7500A. Wannan kirkiyoyi sun amfani da aira a matsayin medium da ake iya yin tsakiya. An yi tsakiya a kan arc elongation, splitting, da cooling tare da arc chute (arc runner). Wannan kirkiyoyi suka iya yin tsakiya a kan short-circuit currents daga 50kA, 80kA, 100kA, ko hatta 150kA.

Abubuwan Dukku da Tushen Sune

• Mechanism na Operation: Yana nan a mafi girman kirkiya, tana ba aikin da ya shafi don separation da closure da ke kusa. Motion na contact na biyu tana taimaka wajen stretch da kuma cool arc, tare da taimaka a kawo tsakiya.

• Intelligent Trip Unit: Yana nan a mafi girman mechanism na operation, wannan shine "brain" na low-voltage circuit breaker. Tana samun signals daga current da voltage tare da sensors, tana kula electrical parameters, tare da kuma koyar da su da LSIG protection settings:

• L: Long-time delay (overload protection)

• S: Short-time delay (short-circuit protection)

• I: Instantaneous (instant trip)

• G: Ground fault protection
  Based on these settings, the trip unit signals the mechanism to open the breaker under overloads or short circuits, providing comprehensive protection.

• Arc Chamber and Terminals: Located at the rear, the arc chamber contains the contacts and arc chute. The lower three-phase outgoing terminals are equipped with:

• Electronic current sensors (for signal input to the trip unit)

• Electromagnetic current transformers (CTs) (to supply operating power to the trip unit)

Mechanism na operation tana da mechanical life na less than 10,000 operations.

Yadda Ake Yi Tsarin Daga Aira zuwa Vacuum Interruption

Tarihin, an samu medium-voltage air circuit breakers amma suna cikin fadada, suna da breaking capacity na kadan, da kuma sun yi arc flash (non-zero arc) da take, wanda yake sauti da yake bukatar.

Amma, vacuum circuit breakers (VCBs) suna da layout na mafi girman sama: mechanism na operation a mafi girman, tare da interrupter a bakin. Amma, interrupter yana amfani da vacuum interrupter (ko "vacuum bottle"), wanda yana da structure na incandescent light bulb — sealed glass ko ceramic envelope evacuated zuwa high vacuum.

A cikin vacuum:

• An bukata small contact gap don insulation da withstand voltage requirements.

• Arc an yi tsakiya rapidly due to the absence of ionizable medium and the efficient diffusion of metal vapor.

Yadda Ake Amfani Da Vacuum Circuit Breakers

Vacuum circuit breakers sun ci gaba da yawa da ake amfani da su a cikin systems na low-voltage, medium-voltage, da high-voltage:

• Low-Voltage VCBs: Typically rated at 1.14kV, with rated currents up to 6300A and short-circuit breaking capacity up to 100kA.

• Medium-Voltage VCBs: Most common in the 3.6–40.5kV range, with currents up to 6300A and breaking capacity up to 63kA. Over 95% of medium-voltage switchgear now uses vacuum interruption.

• High-Voltage VCBs: Single-pole interrupters have reached 252kV, and 550kV vacuum circuit breakers have been achieved through series-connected interrupters.

Farkon Tsarin Dukku

Unlike air circuit breakers that use contact springs, vacuum circuit breakers require the operating mechanism to:

• Provide sufficient opening and closing speed

• Ensure adequate contact pressure

Contact pressure must remain sufficient even after up to 3mm of contact wear, to reliably carry the rated current and withstand the peak short-time current during faults.

Abubuwan Dalilai na Vacuum Circuit Breakers

• High reliability and safety

• Immune to environmental conditions (dust, humidity, altitude)

• Zero arc flash (no external arcing)

• Compact size and long maintenance intervals

These advantages make vacuum breakers ideal for use in hazardous environments such as chemical plants, coal mines, oil & gas facilities, where explosion risks and fire safety are critical.

Real-World Case Study: Vacuum vs. Air Breaker Performance Under Fault

A large chemical plant installed two circuit breakers — one air circuit breaker and one vacuum circuit breaker — in identical circuit configurations and subjected them to the same fault conditions.

The circuit was a tie configuration, where the power sources on either side of the breaker were out of synchronization. This resulted in a transient voltage across the contact gap approaching twice the rated voltage, leading to breaker failure.

Results:

• Air Circuit Breaker:
  Suffered complete destruction. The breaker unit’s enclosure ruptured, and adjacent switchgear on both sides was severely damaged. Extensive reconstruction and replacement were required.

• Vacuum Circuit Breaker:
  The failure was significantly less violent. After replacing the vacuum interrupter and cleaning the arc by-products (soot) from the breaker and compartment, the switchgear was restored to service quickly.

Conclusion

Vacuum circuit breakers demonstrate superior fault containment, safety, and reliability compared to air breakers, especially under severe transient overvoltages. Their sealed vacuum interrupters prevent arc propagation, minimizing damage and downtime.

In explosive or flammable environments such as chemical plants and coal mines, the arc-free operation and robust performance of vacuum circuit breakers provide a clear technological and safety advantage.