Ang Optimal nga Disenyo ug Pagpromosyon ug Aplikasyon sa usa ka Outdoor High-Voltage Vacuum Circuit Breaker

Ang grid ng kuryente usa ka mahamot nga pundasyon ug proteksyon alang sa modernong pagkab-ubo sa ekonomiya ug lipunan. Ang layunin sa pagtukod og matigas ug maayo nga grid sa kuryente mao ang pagtukod og moderno nga sistema sa grid sa kuryente nga lami, makatabang sa kalibutan, epektibo, ug may interaksiyon, aron mapatuman ang siyentipikong pagkab-ubo sa grid sa kuryente, ug isultiha ang grid sa kuryente isip usa ka berde nga plataporma alang sa optimal nga pagbahin sa enerhiya, isip usa ka plataporma sa serbisyo para mohatag sa daghang pangutana sa mga user, ug isip usa ka pundamental nga plataporma alang sa pagprotekta sa pampublikong seguridad sa enerhiya.

Ang high-voltage circuit breakers mao ang pinaka-importante ug kritikal nga mga kontrol ug proteksyon sa sistema sa kuryente. Bisan unsa ang kondisyon sa power line, sama sa walay load, adunay load, o short-circuit fault, kon gikinahanglan nga mogawas, ang circuit breaker kinahanglan mosulay sa handa, kasagaran sa pagbutang o pagbukas sa circuit. Ang iyang mga pangunahon nga tungkulin mao kini:

Ang ZW32-12/630-20 outdoor high-voltage vacuum circuit breaker usa ka gamiton nga komon sa kasagaran sa kasamtangan nga 12 kV distribution network. Giadop niini ang tubo nga three-phase pillar-type, fully-sealed structure, ug may stable ug reliable nga interrupting performance, simple ug concise nga itsura, light weight, small size, ug suitable sa pole-mounted installation. Tungod sa iyang daghang mga abilidad, nahimo kini usa ka popular nga gipili sa mga consumer sa kuryente sukad nito mibuhat sa market. Ang among kompanya usab nagpadayon sa iyang pagbuhat, adunay taas nga mas baya asa 5,000 units kada tuig. Batas sa atong after-sales service sa kataposang mga tuig, miagi mi og teknikal ug teknolohikal nga improvements ug refinements sa mga commonly reported issues sa users, nga nailhan ug gina-apliyar na sa maayo.

1. Design Background and Principles

Ang key focus sa "12th Five-Year Plan" mao ang transformation ug upgrading. Giadvokar nia ang paggamit og high-tech aron bag-o ang tradisyonal nga industriya, pag-improve sa core competitiveness sa produkto pinaagi sa industrial transformation ug upgrading, ug pagpromote sa orderly, healthy, ug rapid nga pagkab-ubo sa electrical engineering industry. Sa iyang 2005 work conference, gi-propone sa State Grid Corporation "promoting standardized construction of the power grid, unifying technical standards for power grid engineering construction at all levels, promoting the application of typical designs, optimizing designs, saving investment, and improving efficiency." Busa, ang pag-atiman sa customers isip ang primary nga atensyon, active response sa customer needs, ug continuous improvement ug upgrading sa product quality in line with standards usa ka urgent nga task alang sa high-voltage switch industry.

Ang design principles mao: safety and reliability, advanced technology, reasonable investment, unified standards, ug efficient operation. Gigihatagan og effort aron ma-achieve ang coordinated unity sa uniformity, reliability, advancement, economy, adaptability, flexibility, timeliness, ug harmony.

2. Content of the Optimal Design

2.1 Design Layout of the Isolator Switch

Sa existing circuit breakers equipped with isolator switches, ang tanang isolator switches gibutang sa outgoing line side. Kini nga arrangement adunay sumala nga drawbacks:

• Drawback 1: Ang isolation blade electrically connected sa outgoing line contact sa current transformer nga gihigdaan sa vacuum circuit breaker. Bisan unsa ang estado sa circuit breaker ug isolator switch, open o closed, ang incoming line end sa circuit breaker adunay live, wala kini makatabang sa inspection ug maintenance sa circuit breaker.

• Drawback 2: Ang proximity sa isolation blade sa current transformer mag-interfere sa installation, wiring, ug daily maintenance sa current transformer, nag-increase sa difficulty sa iyang inspection.

Arong matabangan ang ubang teknikal nga issues, gigamit namo ang sumala nga teknikal nga solusyon, tngn ang Figure 1.

1.Circuit breaker mechanism box 2.Current transformer 3.Insulating post 4.Isolation knife switch 5.Insulating pull rod 6.Post insulator 7.Isolator switch support

2. Content of the Optimal Design

2.1 Design Layout of the Isolator Switch

Ang isolator switch gibutang sa supply side sa circuit breaker, ug gihatag ang reliable mechanical interlock tali sa isolator switch ug circuit breaker.

• Advantage 1: Kon ang circuit breaker ug isolator switch parehas open, obvious nga isolation gap ang maka-form tali sila. Kasagaran, ang installation, maintenance, ug inspection sa circuit breaker mahimo na confident, nag-reduce sa difficulty sa maintenance sa circuit breaker.

• Advantage 2: Ang isolator switch ug current transformer gibutang sa incoming ug outgoing line sides sa circuit breaker, dili sila mag-interfere bisan unsa ang estado sa maintenance, nag-facilitate sa inspection sa current transformer ug isolator switch.

2.2 Flexible Selection of the Current Transformer Ratio

Kasagaran, ang current transformers sa outdoor pole-mounted high-voltage vacuum circuit breakers adunay duha ka installation structures: internal ug external. Tungod sa space limitations, ang most current transformers adunay single-winding design, wala kini makatabang sa users nga adjust ang ratio batas sa load sa hinatud. Nag-increase kini sa investment ug waste of resources.

Arong matabangan kini, gi-adto namo og daghang innovations ug designs sa terms sa structure ug process technology.

• Solution 1: Dual-winding current transformers gihatag alang sa protection ug metering, satisfying the needs of different power users.

• Solution 2: Multi-tap current transformers gihatag alang sa over-current protection. For example, current transformers with ratios of 200/5, 400/5, and 600/5 are configured. A control box is set on the left side of the box shell, and a CT ratio conversion switch is designed at the bottom of the control box. This greatly facilitates users to adjust the ratio on-site according to the actual load, as shown in Figures 2, 3, and 4.

2.3 Increasing the External Insulation Creepage Distance

Ang creepage distance (leakage distance) refers to the shortest distance along the insulating surface between two conductors. From the perspective of product reliability, air insulation is the most reliable. As long as the net insulation distances between conductors of different phases and between conductors and the ground are ensured, the insulation can be guaranteed.

Outdoor products operate under relatively harsh conditions and are exposed to various climatic conditions throughout the year. This makes them prone to mechanical or electrical problems, which directly affect the reliability and safety of power supply and normal production. Therefore, this factor should be fully considered in design and manufacturing to ensure the product's reliability in various environments.

In response to the above-mentioned situation, for all insulating parts of the outdoor switch directly exposed to the external environment, including bushings, current transformers, insulating pull rods, and post insulators, we have increased the density of the shed skirts. As a result, the creepage distance has reached 372 mm (as shown in Figure 1). This improvement enhances the overall structural insulation performance, expands the usage environment and locations of this type of vacuum circuit breaker, allowing it to be used in environments with high dust, high humidity, and heavy salt spray, and eliminates potential short-circuit risks caused by insulation issues.

1.CT ratio conversion switch 2.Control box Front elevation view of the improved circuit breaker (Figure 2)

Figure 3 Schematic diagram of the CT ratio conversion switchNote: The "0" position indicates no protection and short circuit.

Upgrading to an Intelligent Circuit Breaker

With the continuous expansion of the automation field in the power system, distribution network automation products have ushered in new development opportunities. Based on the ZW32-12/630-20 model, our company has independently developed a new product: the outdoor intelligent high-voltage vacuum circuit breaker. It is mainly composed of four major parts: the vacuum circuit breaker body, a three-phase integrated zero-sequence current transformer, an FDK-type controller, and an external voltage transformer, as shown in Figure 5.

This intelligent circuit breaker is widely used in 10 kV urban and rural overhead loop network lines. It can serve as a sectional isolating switch and a tie switch, and is an automated switching device that enables the automatic allocation of load in the loop network lines. In the branch lines supplying large users, it can be used as a boundary switch (commonly known as a "watchdog"). In the overhead feeder distribution network, it can function as a recloser and a sectionizer.

The boundary circuit breaker features a remote management mode, protection control functions, and communication functions. It can reliably detect and judge zero-sequence currents in the milliampere range and phase-to-phase short-circuit fault currents within its boundary. It can automatically cut off single-phase grounding faults and phase-to-phase short-circuit faults, ensuring the stable and reliable operation of the power grid.

Main Functions

• Function 1: Single-phase Grounding Fault Handling
  When a single-phase grounding fault occurs in the user's branch line, the intelligent circuit breaker automatically trips. Other branch users in the substation and on the feeder are not affected by the fault.

• Function 2: Inter-phase Short-circuit Fault Isolation
  In case of an inter-phase short-circuit fault in the user's branch line, the intelligent circuit breaker trips before the outgoing line protection switch of the substation, automatically isolating the faulty line without causing power outages for other branch users on the feeder.

• Function 3: Rapid Fault Location
  After the intelligent circuit breaker trips due to a fault in the user's branch line, only the responsible user experiences a power outage. The user actively reports the fault information, enabling the power supply department to quickly dispatch personnel to the site for troubleshooting.

• Function 4: User Load Monitoring
  The intelligent circuit breaker can be equipped with wired or wireless communication accessories to transmit monitoring data to the power monitoring and management center, enabling remote real-time data monitoring of the user's load. The intelligent circuit breaker can be tripped via SMS or a computer-based back-end system.

Conclusion

Outdoor high-voltage vacuum circuit breakers use overhead connections for both incoming and outgoing lines. They offer advantages such as small footprint, clear layout, convenient operation and maintenance, fewer structures, and fast construction and installation. During the design and manufacturing processes, continuous improvement and optimization of various performance aspects should be carried out to achieve excellence, ensuring the safe and reliable operation of the product.