Name: fault coordination with reclosers and fuses
Uploaded: 2024-11-21T14:54:34.000Z
Duration: 1 min 26 s
Channel: JoVE

자동 회로 리클로저는 사전 설정된 순서에 따라 AC 회로를 차단하고 자동으로 다시 닫음으로써 배전 회로를 보호합니다.
머리 위 회로에서 나뭇가지나 야생 동물로 인해 발생하는 일시적인 결함은 리클로저에 의해 제거되어 서비스 중단을 최소화하고 고객 경험을 개선합니다.
그러나 리클로저는 전원이 공급되는 접지 수준 도체와 접촉하는 경우 위험할 수 있습니다.
방사형 배전 회로에서는 퓨즈, 리클로저 및 시간 지연 과전류 계전기의 조합으로 보호가 이루어집니다. 역 특성을 가진 이러한 릴레이는 리클로저 및 T형 퓨즈와 조정됩니다.
릴레이 설정은 릴레이 활성화 전에 오류를 지우기 위해 다시 닫기 작업의 우선 순위를 지정합니다.
오류가 지속되면 recloser가 잠기거나 퓨즈가 다운스트림 오류에 작용합니다. 여러 번 재폐쇄 한 후 시간 지연 과전류 릴레이가 변전소 차단기를 엽니 다.
시간-전류 곡선은 리클로저와 T형 퓨즈 간의 배위를 나타냅니다.
리클로저는 최대 부하 전류보다 높은 최소 정격에서 트립되어 빠르고 지연된 작동을 수행하여 일시적인 결함을 제거하는 동시에 퓨즈가 영구 오류를 해결할 수 있도록 합니다.

재폐쇄기 및 퓨즈

Reclosers and Fuses

자동 회로 재폐쇄기는 사전 설정된 순서에 따라 AC 회로를 차단하고 자동 재폐쇄하여 배전 회로의 보호를 강화합니다. 이는 종종 나무 가지나 야생 동물로 인해 발생하는 가공 배전선의 일시적인 고장을 효과적으로 관리하여 서비스를 잠시 중단하여 전반적인 안정성을 개선합니다. 그러나 재폐쇄기나 지상의 통전된 끊어진 도체와의 접촉은 심각한 위험을 초래할 수 있습니다.

방사형 분배 회로에 대한 포괄적인 보호 체계는 퓨즈, 재폐쇄기 및 시간 지연 과전류 릴레이를 통합합니다. 종종 매우 역방향 시간-전류 곡선을 특징으로 하는 이러한 릴레이는 재폐쇄기 및 유형 T 퓨즈와 조정되도록 설계되었습니다. 릴레이 설정은 릴레이가 작동하기 전에 오류를 제거하기 위해 재폐쇄기 작동을 우선시합니다. 오류가 지속되면 재폐쇄기는 결국 여러 번 시도한 후 잠기므로 퓨즈가 하류 오류를 해결할 수 있습니다. 그런 다음 시간 지연 과전류 릴레이는 여러 번의 재폐쇄기 작동 후 변전소 차단기를 엽니다.

이 조정은 시간-전류 곡선을 사용하여 시각화됩니다. 유형 T 퓨즈는 재폐쇄기와의 적절한 조정을 보장하기 위해 최대 탭 부하에 따라 선택됩니다. 재폐쇄기는 최대 부하 전류에 따라 최소 트립 정격으로 설정되어 저온 부하 픽업을 무시합니다. 일반적으로 두 번의 빠른 작업을 수행한 다음 두 번의 지연된 작업을 수행하여 일시적인 오류가 스스로 해결되고 다운스트림 퓨즈가 영구적인 오류를 해결할 수 있도록 합니다.

방사형 시스템에서 효과적인 보호는 과전류 릴레이의 세심한 조정과 다양한 오류 조건에서 시스템 동작에 대한 철저한 이해에 달려 있습니다. 이러한 조정은 오류가 효율적으로 격리되어 시스템에 미치는 영향을 최소화하고 신뢰성을 유지하도록 합니다. 최신 디지털 재폐쇄기 및 릴레이는 실시간 모니터링, 통신 기능, 정확한 타이밍 조정과 같은 고급 기능을 제공하여 이러한 조정을 더욱 강화하여 전력 시스템의 전반적인 안정성과 보호에 기여합니다.

자동 회로 리클로저는 사전 설정된 순서에 따라 AC 회로를 차단하고 자동으로 다시 닫음으로써 배전 회로를 보호합니다.
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Education

교육

JoVE Core

Electrical Engineering

전기공학

Unit 1

제1단원

System Protection

시스템 보호

KEY TERMS AND CONCEPTS

주요 용어 및 개념

fault coordination with reclosers and fuses

Fault coordination with reclosers and fuses helps protect radial distribution circuits. A recloser is an automatic switch that interrupts AC power and then closes again on a preset schedule. This brief outage can clear temporary faults on overhead lines, such as those caused by tree limbs or wildlife, and it can improve overall reliability.

Reclosers and their ground-level hazards also matter. Contact with a recloser or with a broken energized conductor on the ground can be dangerous. That is why protection in distribution systems must be planned so faults are isolated quickly and safely.

A full protection scheme uses fuses, reclosers, and time-delay overcurrent relays. A time-delay overcurrent relay is a relay that waits longer to trip when the fault current is smaller. These relays often use an extremely inverse time-current curve. They are set to let the recloser act first, while still protecting the substation breaker if the fault remains.

Coordination is shown with time-current curves. Type T fuses are chosen from the maximum tap load so they work properly with reclosers. Reclosers are set with minimum trip ratings based on the maximum load current, which helps them override cold load pickup. In many cases, they make two fast operations and then two delayed ones. This gives temporary faults a chance to clear and lets downstream fuses clear permanent faults. If the fault still does not clear, the recloser locks out after several tries, and the overcurrent relay opens the substation breaker after the recloser operations.

Fault Coordination with Reclosers and Fuses

fault-coordination-with-reclosers-and-fuses

instrument transformers

Voltage and Current Sensing in Power Grids

Instrument transformers help power substations measure voltage and current safely. They create isolated replicas of electrical signals for measurement and protection. These devices support protective relays and other monitoring equipment that keep power systems stable and reliable. The two main types are voltage transformers, or VTs, and current transformers, or CTs. A voltage transformer reduces the primary voltage to a lower level that relays and measuring devices can use. A current...

overcurrent relays

Relay Settings for Circuit Fault Protection

Overcurrent relays protect circuits by sensing excess current through the secondary side of a current transformer. They are an important part of circuit protection and help keep power systems stable when a fault occurs. Two main relay types are used here: instantaneous and time-delay overcurrent relays. An instantaneous relay trips right away when current rises above the pickup current, which is the preset level that starts the relay. It then energizes the circuit breaker trip coil at once,...

radial system protection

Breaker Coordination in Radial Systems

Breaker coordination in radial systems uses time-delay overcurrent relays to limit load interruption. When a fault happens, the nearest breaker should open first. Upstream breakers stay closed because they are set with longer delays. This lets the fault be isolated while the rest of the system keeps running. If a fault is downstream of the third breaker, only the third breaker should trip. That removes power from the load beyond the fault. The second breaker keeps a longer delay setting, so...

reclosers and fuses

Fault coordination with reclosers and fuses helps protect radial distribution circuits. A recloser is an automatic switch that interrupts AC power and then closes again on a preset schedule. This brief outage can clear temporary faults on overhead lines, such as those caused by tree limbs or wildlife, and it can improve overall reliability. Reclosers and their ground-level hazards also matter. Contact with a recloser or with a broken energized conductor on the ground can be dangerous. That is...

directional relays

Directional Relays in Power System Protection

Directional relays help protect power systems by telling forward faults from reverse faults. They are used when fault current flows mainly in one direction on a line. This makes the relay useful for safe and efficient fault clearing. On a protected line, a fault downstream, or to the right of the current transformer, usually makes the fault current lag the bus voltage by about 90 degrees. This is called the forward direction. A fault upstream, or to the left, may make the fault current lead...

zones of protection

Power System Protection Zones

Power system protection zones divide the network into sections so faults can be isolated quickly. These zones can include generators, transformers, buses, transmission lines, distribution lines, and motors. Each zone is shown with closed dashed lines and contains one or more components. Circuit breakers are placed at the borders where protection zones meet. If a fault happens in one zone, the related breakers open and disconnect only that section. A fault in one area, such as a kitchen in the...

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Impedance Relays for Fault Detection

Impedance relays help protect power lines by watching the voltage-to-current ratio on a line. They measure the apparent impedance, which is the electrical opposition the relay sees at that point in the system. This makes them useful when time-delay overcurrent relays are hard to coordinate in complex radial systems and when directional overcurrent relays are difficult to use in multi-source transmission loops. These relays respond strongly during a fault. As current rises and voltage falls,...

differential relays

Differential Relay Protection in Power Systems

Differential relays protect generators, buses, and transformers by comparing currents at different points in a power system. When the currents do not match, the relay detects the difference and opens the circuit breaker. Under normal conditions, the current entering a generator, i1, equals the current leaving it, i2. If a fault occurs, these currents become unequal, and the difference current flows through the relay operating coil to trip the relay. An electromechanical differential relay is...

pilot and numeric relaying

Pilot Relays and Digital Protection

Pilot relays and numeric relays help protect power systems. Pilot relaying is a form of differential protection, which compares electrical quantities at equipment terminals through a communication channel instead of a direct relay link. It is especially useful for transmission lines with terminals far apart, often up to 80 km on 69 to 115 kV lines. Pilot relaying can use several communication channels. Pilot wires are separate electrical circuits that operate at DC, 50 to 60 Hz, or audio...

key terms and concepts

Learn how reclosers, type T fuses, and time-delay overcurrent relays coordinate to clear temporary faults, lock out persistent faults, and protect distribution circuits.

Fault Coordination with Reclosers and Fuses | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

Fault Coordination with Reclosers and Fuses

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