Bạn đang xem: Circuit breaker là gì
Chức năng cơ bản của nó là ngắt chiếc năng lượng điện sau khi phân phát hiện tại lỗi. Không y như cầu chì, vận động một lượt cùng sau đó đề xuất được sửa chữa, một cỗ ngắt mạch rất có thể được đóng góp lại (bằng tay hoặc từ động) để thường xuyên hoạt động bình thường. Bộ ngắt mạch được sản xuất với những form size khác nhau, tự các đồ vật ngắt mạch nhỏ đảm bảo mạch điện trong những hộ mái ấm gia đình đến các thứ ngắt mạch béo đảm bảo những mạch năng lượng điện mang lại nhà máy, nhà máy với tổng thể quần thể cư dân. Chức năng bình thường của bộ ngắt điện hoặc cầu chì hệt như một phương tiện đi lại tự động sa thải nguồn điện áp xuất phát từ một hệ thống bị lỗi với hay được viết tắt là ADS (Automatic Disconnection of Supply).The circuit breaker is an absolutely essential device in the modern world, và one of the most important safety mechanisms in your home. Whenever electrical wiring in a building has too much current flowing through it, these simple machines cut the power until somebody toàn thân can fix the problem. Without circuit breakers (or the alternative sầu,fuses), household electrithành phố would be impractical because of the potential for fires & other mayhem resulting from simple wiring problems và equipment failures.In this article, we'll find out how circuit breakers và fuses monitor electrical current and how they cut off the power when current levels get too high. As we'll see, the circuit breaker is an incredibly simple solution to a potentially deadly problem.
Electricityis defined by three major attributes:VoltageCurrentResistanceVoltageis the "pressure" that makes an electric charge move.Currentis the charge's "flow" -- the rate at which the charge moves through the conductor, measured at any particular point. The conductor offers a certain amount ofresistancelớn this flow, which varies depending on the conductor's composition & kích cỡ.Voltage, current & resistanceare all interrelated -- you can't change one without changing another. Current is equal to lớn voltage divided by resistance (commonly written asI = v / r). This makes intuitive sầu sense: If you increase the pressure working on electric charge or decrease the resistance, more charge will flow. If you decrease pressure or increase resistance, less charge will flow. To learn more, kiểm tra outHow Electrithành phố Works.So how does all of this come together in your home? Let's find out.Circuit Breaker: At Work in Your HomeThepower distribution griddelivers electricity from a power plant khổng lồ your house. Inside your house, the electric charge moves in a large circuit, which is composed of many smaller circuits. One end of the circuit, thehot wire, leads to lớn the power plant. The other over, called theneutral wire, leads toground. Because the hot wire connects lớn a high energy source, & the neutral wire connects to an electrically neutral source (the earth), there is a voltage across the circuit -- charge moves whenever the circuit is closed. The current is said to lớn bealternating current, because it rapidly changes direction. (SeeHow Power Distribution Grids Workfor more information.)The power distribution grid delivers electriđô thị at a consistent voltage (1đôi mươi và 240 volts in the United States), but resistance (và therefore current) varies in a house. All of the differentlight bulbs& electrical appliances offer a certain amount of resistance, also described as theload. This resistance is what makes the appliance work. A light bulb, for example, has a filament inside that is very resistant lớn flowing charge. The charge has to work hard lớn move sầu along, which heats up the filament, causing it lớn glow.In building wiring, the hot wire and the neutral wire never touch directly. The charge running through the circuit always passes through an appliance, which acts as a resistor. In this way, the electrical resistance in appliances limits how much charge can flow through a circuit (with a constant voltage & a constant resistance, the current must also be constant). Appliances are designed to keep current at a relatively low cấp độ for safety purposes. Too much charge flowing through a circuit at a particular time would heat the appliance's wires và the building's wiring to lớn unsafe levels, possibly causing a fire.This keeps the electrical system running smoothly most of the time. But occasionally, something will connect the hot wire directly to lớn the neutral wire or something else leading to lớn ground. For example, a fanmotormight overheat và melt, fusing the hot and neutral wires together. Or someone mightdrive sầu a nail into the wall, accidentally puncturing one of the power lines. When the hot wire is connected directly lớn ground, there is minimal resistance in the circuit, so the voltage pushes a huge amount of charge through the wire. If this continues, the wires can overheat & start a fire.The circuit breaker's job is to cut off the circuit whenever the current jumps above sầu a safe cấp độ. In the following sections, we'll find out how it does this.The simplest circuit protection device is thefuse. A fuse is just a thin wire, enclosed in a casing, that plugs inkhổng lồ the circuit. When a circuit is closed, all charge flows through the fuse wire -- the fuse experiences the same current as any other point along the circuit. The fuse is designed todisintegratewhen it heats up above sầu a certain màn chơi -- if the current climbs too high, it burns up the wire. Destroying the fuse opens the circuit before the excess current can damage the building wiring.
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The problem with fuses is they only work once. Every time you blow a fuse, you have to lớn replace it with a new one. A circuit breaker does the same thing as a fuse -- it opens a circuit as soon as current climbs khổng lồ unsafe levels -- but you can use it over & over again.The basic circuit breaker consists of a simpleswitch, connected lớn either a bimetallic strip or anelectromagnet. The diagram below shows a typical electromagnet thiết kế.The hot wire in the circuit connects to lớn the two ends of the switch. When the switch is flipped khổng lồ the on position, electrithành phố can flow from the bottom terminal, through the electromagnet, up lớn the moving contact, across lớn the stationary contact và out khổng lồ the upper terminal.The electricitymagnetizesthe electromagnet (SeeHow Electromagnets Worklớn find out why). Increasing current boosts the electromagnet's magnetic force, & decreasing current lowers the magnetism. When the current jumps to lớn unsafe levels, the electromagnet is strong enough to lớn pull down a metal lever connected khổng lồ the switch linkage. The entire linkage shifts, tilting the moving liên hệ away from the stationary tương tác to break the circuit. The electricity shuts off.Cliông xã on the circuit breaker khổng lồ release the switch.Abimetallic stripthiết kế works on the same principle, except that instead of energizing an electromagnet, the high current bends a thin strip to move sầu the linkage. Some circuit breakers use anexplosive chargekhổng lồ throw the switch. When current rises above sầu a certain level, it ignites explosive material, which drives a piston khổng lồ open the switch.Breaker Design: AdvancedMore advanced circuit breakers useelectroniccomponents (semiconductordevices) lớn monitor current levels rather than simple electrical devices. These elements are a lot more precise, & they shut down the circuit more quickly, but they are also a lot more expensive. For this reason, most houses still use conventional electric circuit breakers.One of the newer circuit breaker devices is theground fault circuit interrupter, orGFCI. These sophisticated breakers are designed to protect people from electrical shock, rather than prevent damage lớn a building's wiring. The GFCI constantly monitors the current in a circuit's neutral wire và hot wire. When everything is working correctly, the current in both wires should be exactly the same. As soon as the hot wire connects directly lớn ground (if somebody toàn thân accidentally touches the hot wire, for example), the current màn chơi surges in the hot wire, but not in the neutral wire. The GFCI breaks the circuit as soon as this happens, preventing electrocution. Since it doesn't have sầu to lớn wait for current to climb to unsafe levels, the GFCI reacts much more quickly than a conventional breaker.All the wiring in a house runs through acentral circuit breaker panel(or fuse box panel), usually in the basement or a closet. A typical central panel includes about a dozen circuit breaker switches leading lớn various circuits in the house. One circuit might include all of the outlets in the living room, and another might include all of the downstairs lighting. Larger appliances, such as a centralair conditioningsystem or arefrigerator, are typically on their own circuit.
