Name: relay settings for circuit fault protection
Uploaded: 2024-11-21T14:54:34.000Z
Duration: 1 min 26 s
Channel: JoVE

변류기의 2차 전류에 연결된 과전류 계전기는 회로를 보호하는 데 중요합니다.
순간 및 시간 지연 과전류 릴레이의 두 가지 유형이 있습니다.
순간 과전류 릴레이는 입력 전류가 사전 설정된 값인 픽업 전류를 초과하자마자 반응합니다. 이 동작은 회로 차단기 트립 코일에 즉시 전원을 공급합니다.
시간 지연 과전류 릴레이도 입력 전류에 응답하지만 입력 전류의 크기에 따라 달라지는 의도적인 지연을 포함합니다.
예를 들어, 변전소를 생각해 보십시오. 오류가 발생하여 전류 서지가 발생하면 순간 릴레이가 즉시 트립됩니다.
대조적으로, 시간 지연 릴레이는 트리핑 없이 경미한 서지를 허용하지만 더 큰 결함에 대해서는 여전히 빠르게 작동합니다.
이 릴레이에는 현재 탭과 시간 다이얼의 두 가지 설정이 있습니다.
릴레이의 선택과 설정은 소스, 라인 및 부하에 따라 다릅니다. 다른 릴레이는 더 높은 고장 전류에서 더 빠르게 작동합니다.
전기 기계 시간 지연 과전류 계전기는 입력 전류에 의해 유도된 자기장 아래에서 회전하는 전도성 알루미늄 디스크를 사용하여 작동합니다. 입력 전류가 클수록 접점 닫힘 속도가 빨라집니다.

과전류 릴레이

Overcurrent Relays

회로 보호에 필수적인 과전류 릴레이는 전류 변압기의 2차 전류에 연결됩니다. 과전류 릴레이에는 순시 및 시간 지연의 두 가지 주요 유형이 있습니다.

순간 과전류 릴레이는 입력 전류가 픽업 전류라고 알려진 미리 정해진 값을 초과하면 즉시 작동하여 회로 차단기 트립 코일에 즉시 전원을 공급합니다. 이러한 빠른 대응은 심각한 오류를 신속하게 해결하는 데 필수적입니다.

반면 시간 지연 과전류 릴레이는 입력 전류의 크기에 따라 달라지는 의도적인 응답 지연을 포함합니다. 예를 들어, 변전소에서 순간 릴레이는 픽업 전류 이상의 고장 유도 전류 서지를 감지하자마자 즉시 트립합니다. 반면 시간 지연 릴레이는 사소한 서지가 트립되지 않고 통과하도록 허용하지만 중대한 고장에는 신속하게 대응합니다.

이러한 릴레이는 전류 탭과 시간 다이얼이라는 두 가지 기본 설정을 사용하여 구성됩니다. 릴레이 유형과 설정의 적절한 선택은 시스템의 소스, 라인 및 부하의 특정 특성에 영향을 받습니다. 특히 시간 지연 릴레이는 더 높은 고장 전류에서 더 빠르게 작동하도록 설계되어 맞춤형 보호를 제공합니다.

전기기계식 시간 지연 과전류 계전기는 입력 전류에 의해 생성된 자기장 내에서 회전하는 전도성 알루미늄 디스크를 통해 작동합니다. 디스크의 회전 속도는 입력 전류의 크기에 비례하여 릴레이 접점이 더 큰 전류로 더 빨리 닫힙니다. 이 메커니즘은 전력 시스템의 다양한 오류 조건에 대한 안정적이고 조절 가능한 보호를 보장합니다.

이러한 릴레이는 보호 장치의 정확한 작동에 필수적이며 전력 시스템의 안전하고 안정적인 작동을 보장합니다. 과전류 릴레이는 고장 전류를 효과적으로 관리함으로써 시스템 안정성을 유지하고 장비 손상을 방지하는 데 도움이 됩니다.

변류기의 2차 전류에 연결된 과전류 계전기는 회로를 보호하는 데 중요합니다.
두 가지 유형이 있습니다 : 순간 ...

Education

교육

JoVE Core

Electrical Engineering

전기공학

Unit 1

제1단원

System Protection

시스템 보호

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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, which is useful for severe faults that need very fast action.

A time-delay overcurrent relay works differently. It adds a planned delay, and that delay depends on how large the input current is. In a power substation, it can let small surges pass without tripping, but it still responds quickly to major fault currents.

These relays are adjusted with two main settings: the current tap and the time dial. The best relay type and settings depend on the sources, lines, and loads in the system. Time-delay relays are also designed to act faster when fault current is higher.

An electromechanical time-delay relay uses a conducting aluminum disc that turns in a magnetic field created by the input current. The disc spins faster as the current increases, so the relay contacts close sooner during larger faults. This adjustable action helps protect equipment and supports reliable operation of power systems.

Relay Settings for Circuit Fault Protection

relay-settings-for-circuit-fault-protection

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

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

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...

line protection with impedance relays

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 instantaneous and time-delay overcurrent relays protect circuits, use pickup current and time dial settings, and respond to fault currents.

Relay Settings for Circuit Fault Protection | 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

Relay Settings for Circuit Fault Protection

Description

Transcript

Tags