Switçek Bixtayî vs Separatûr vs Vakûmî Switç Karkirina: Ferqên Serekeya û Fonksyonan
Li bûyer e ku Li Break Switch?
Li bûyer e ku li break switch û bir kontrol cihaz e ku bi mekanîzmê ya basit de arc-extinguishing ve hatîn, û yekan dikare li ser baran daxuyin da çavkaniyê re circuitan biguherîne. E dikare li ser baran daxuyin da çavkaniyê re circuitan biguherîne, amma ne dikare li ser baran daxuyin da short-circuit currents re. Buna, e diha parastîn da li ser high-voltage fuse, li virane fuse an short-circuit faults radyar bike.
Functions of a Load Break Switch:
Interrupting and Making Function: Ji ber ku li ser baran daxuyin da arc-extinguishing ê ya herêmdehatî ye, li bûyer e ku li break switch bikar îst bi tevahî li ser baran daxuyin da çavkaniyê re circuitan biguherîne û wekhevîne derbasdar (seda 3-4 ji). E dikare transformers bêtbaran bi kapasiteyên piştî wê yên li ser disconnectors allowed re wereke, rêzan bêtbaran bi kapasiteyên piştî wê yên li ser disconnectors allowed re wereke, û jîyan capacitor banks mezin bikar îst.
Substitution Function: Li bûyer e ku li break switch û current-limiting fuse li ser series û bêtirî dikare circuit breaker wereke. Li bûyer e ku li break switch bikar îst bi tevahî li ser baran daxuyin da overloads mezin re, amma current-limiting fuse bikar îst bi tevahî li ser baran daxuyin da overloads mezin û hemî short-circuit currents.
Combined Device: Li ser assembly integrated e ku li bûyer e ku li break switch û current-limiting fuse li ser series û bêtirî "Switch-Fuse Combination" di national standards de namekirin. Fuse dikare li ser supply side û load side ya switch wereke. Ji ber ku fuse replacement pêşniyê ne, li ser supply side wereke werger e, li virane li bûyer e ku li break switch bikar îst isolator wereke, li virane voltage applied to the current-limiting fuse isolate bike.
What is a Disconnector (Isolator)?
Li bûyer e ku disconnector ûku kontrol cihaz e ku çi arc-extinguishing mechanism tune. Li ser function primary û li ser power sources isolate bike û safe maintenance of other electrical equipment ensure bike; buna, operation under load strictly prohibited. Amma, di şertên xusûl de, li ser low-power circuits connect û disconnect permitted e. E yekan e ku most widely û frequently used devices in high-voltage switchgear.
Functions of a Disconnector:
Establishing a Safe Isolation Point: Di opening de, reliable insulating gap create bike, clearly disconnecting the equipment û line under maintenance from the power source, ensuring the safety of personnel û equipment.
Circuit Switching: To switch circuit connections according to operational requirements.
Interrupting Small Currents: E dikare small currents in circuits, such as charging currents of bushings, busbars, connectors, û short cables; capacitive currents of switch equalizing capacitors; circulating currents during double-busbar transfer operations; û excitation currents of voltage transformers interrupt bike.
Interrupting Unloaded Transformer Magnetizing Current: Depending on the structural type, e dikare magnetizing current of unloaded transformers up to a certain capacity interrupt bike.
Classification:
By Installation Location: Can be divided into outdoor high-voltage disconnectors û indoor high-voltage disconnectors.
Outdoor Type: Designed to withstand harsh environmental conditions such as wind, rain, snow, pollution, condensation, ice, û heavy frost, suitable for open-air installation.
By Insulating Post Structure: Can be classified as single-column, double-column, û triple-column disconnectors. The single-column disconnector uses the vertical space directly beneath overhead busbars as the electrical insulation for the break, offering significant advantages: saving land area, reducing connecting conductors, û providing clear visual indication of open/closed status. In EHV transmission systems, the space-saving effect of single-column disconnectors in substations is particularly pronounced.
Note: Disconnectors are primarily used in low-voltage equipment, such as residential û building low-voltage final distribution systems. The description stating its main function is "interrupting û making lines under load" is incorrect; its primary function is power source isolation.
What is a Vacuum Circuit Breaker?
A vacuum circuit breaker derives its name from using high vacuum as both the arc-quenching medium û the insulating medium between contacts after interruption. It features a compact size, light weight, suitability for frequent operation, û maintenance-free arc interruption, making it widely used in distribution networks.
Vacuum circuit breakers are primarily used in indoor distribution installations for 3–10 kV, 50 Hz three-phase AC systems. They serve as protection û control elements for electrical equipment in industrial û mining enterprises, power plants, û substations, especially suitable for applications requiring oil-free operation, minimal maintenance, û frequent operation. They can be installed in mid-mounted switchgear, double-deck cabinets, û fixed cabinets as control û protection switches for high-voltage electrical equipment.
Working Principle of Vacuum Circuit Breakers
When the moving û fixed contacts are opened by the operating mechanism, an arc forms between them. The contact surfaces vaporize metal under high temperature. Due to the specially designed contact shape, the current generates a magnetic field that drives the arc rapidly along the tangential direction of the contact surface. Part of the metal vapor condenses on the metal shield (screen). When the current naturally passes through zero, the arc extinguishes, û the dielectric strength between the contacts recovers rapidly.
Function of Vacuum Circuit Breakers
Circuit breakers provide protection functions including overload, short-circuit, û undervoltage protection, effectively safeguarding circuits û power sources.
Differences Between Load Break Switches û Disconnectors
Interrupting Current Capability:
A disconnector lacks an arc-extinguishing mechanism û can only interrupt no-load current, unable to handle load current û short-circuit current. Operation must be performed only when the circuit is completely de-energized û unloaded; operating under load is strictly prohibited to prevent safety incidents.
A load break switch has an arc-extinguishing mechanism, enabling it to interrupt rated load currents û overloads up to a certain multiple, but it still cannot interrupt short-circuit currents.
Presence of Arc-Extinguishing Mechanism:
This is the fundamental difference. An arc-extinguishing mechanism aids in the opening û closing operations of the switch û effectively limits û extinguishes arcs, enhancing operational safety. Consequently, most switching devices (especially those designed to interrupt current) are equipped with arc-extinguishing mechanisms.
Functional Purpose:
A disconnector is primarily used to establish a clear break point in high-voltage circuits, isolating energized sections from de-energized sections for maintenance, ensuring personnel safety.
A load break switch is used in fixed high-voltage installations to interrupt fault currents (overloads) û rated operating currents of equipment. Although both are used in high-voltage systems, their functional roles differ.
Differences Between High-Voltage Load Break Switches û Vacuum Circuit Breakers
Interrupting Capacity: A high-voltage load break switch can interrupt under load û has self-extinguishing capability, but its interrupting capacity is small û limited.
Structural Differences: High-voltage disconnectors typically cannot interrupt under load û lack an arc chute in their structure (a few specially designed disconnectors can interrupt small loads, but their structure is relatively simple).
Isolation Function: Both high-voltage load break switches û high-voltage disconnectors can create a visible break point, whereas most circuit breakers do not have this function (except for a few circuit breakers with isolation capability).
Protection Functions:
High-voltage disconnectors have no protection functions.
Protection for high-voltage load break switches typically relies on series-connected high-voltage fuses, providing only instantaneous û overcurrent protection.
High-voltage circuit breakers (such as vacuum circuit breakers) can be designed with very high interrupting capacities, primarily protected by current transformers in conjunction with secondary protection devices, offering multiple protection functions including short-circuit, overload, û earth leakage protection.
Functional Positioning: A high-voltage load break switch functions between a high-voltage circuit breaker û a high-voltage disconnector. It is often used in series with a high-voltage fuse for controlling power transformers. It can interrupt load currents û overloads, but due to its inability to interrupt short-circuit currents, it must rely on fuses for short-circuit protection.
