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Fault (power Engineering)
In an electric power system, a fault is a defect that results in abnormality of electric current. A fault current is any abnormal electric current. For example, a short circuit in which a live wire touches a neutral or ground wire is a fault. An open-circuit fault occurs if a circuit is interrupted by a failure of a current-carrying wire (phase or neutral) or a blown Fuse (electrical), fuse or circuit breaker. In a "ground fault" or "earth fault", current flows into the earth. In Three-phase electric power, three-phase systems, a fault may involve one or more phases and ground, or may occur only between phases. In a polyphase system, a fault may affect all phases equally, which is a "symmetric fault". If only some phases are affected, the resulting "asymmetric fault" becomes more complicated to analyse. The analysis of these types of faults is often simplified by using methods such as symmetrical components. The prospective short-circuit current of a predictable fault can be calcul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Power System
An electric power system is a network of electrical components deployed to supply, transfer, and use electric power. An example of a power system is the electrical grid that provides power to homes and industries within an extended area. The electrical grid can be broadly divided into the Electric generator, generators that supply the power, the electric power transmission, transmission system that carries the power from the generating centers to the Distribution board, load centers, and the electric power distribution, distribution system that feeds the power to nearby homes and industries. Smaller power systems are also found in industry, hospitals, commercial buildings, and homes. A single line diagram helps to represent this whole system. The majority of these systems rely upon three-phase electric power, three-phase AC power—the standard for large-scale power transmission and distribution across the modern world. Specialized power systems that do not always rely upon thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Cable
A power cable is an electrical cable used specifically for transmission of electric energy, electrical power. It is an assembly of one or more electrical conductors, usually held together in a single bundle with an insulator (electricity), insulating sheath, although some power cables are simply rigged as exposed live wire (electricity), live wires. Power cables may be detachable portable cords (typically coupled with adaptors), or installed as permanent electrical wiring, wirings within buildings and non-building structure, structures, underground power line, buried in the ground, submarine power cable, laid underwater or overhead power line, run overhead. Power cables that are bundled inside thermoplastic-sheathed cable, thermoplastic sheathing and that are intended to be run inside a building are known as NM-B (nonmetallic sheathed building cable). Small flexible power cables are used for electrical devices such as computers and peripherals, mobile devices, home appliances, l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Flow Study
In power engineering, a power-flow study (also known as power-flow analysis or load-flow study) is a numerical analysis of the flow of electric power in an interconnected system. A power-flow study usually uses simplified notations such as a one-line diagram and per-unit system, and focuses on various aspects of AC power parameters, such as voltage, voltage angles, real power and reactive power. It analyzes the power systems in normal steady-state operation. Power-flow or load-flow studies are important for planning future expansion of power systems as well as in determining the best operation of existing systems. The principal information obtained from the power-flow study is the magnitude and phase angle of the voltage at each bus, and the real and reactive power flowing in each line. Commercial power systems are usually too complex to allow for hand solution of the power flow. Special-purpose network analyzers were built between 1929 and the early 1960s to provide laboratory-s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software
Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital computers in the mid-20th century. Early programs were written in the machine language specific to the hardware. The introduction of high-level programming languages in 1958 allowed for more human-readable instructions, making software development easier and more portable across different computer architectures. Software in a programming language is run through a compiler or Interpreter (computing), interpreter to execution (computing), execute on the architecture's hardware. Over time, software has become complex, owing to developments in Computer network, networking, operating systems, and databases. Software can generally be categorized into two main types: # operating systems, which manage hardware resources and provide services for applicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arc-fault Circuit Interrupter
An arc-fault circuit interrupter (AFCI) or arc-fault detection device (AFDD) is a circuit breaker that breaks the circuit when it detects the electric arcs that are a signature of loose connections in home wiring. Loose connections, which can develop over time, can sometimes become hot enough to ignite house fires. An AFCI selectively distinguishes between a harmless arc (incidental to normal operation of switches, plugs, and brushed motors), and a potentially dangerous arc (that can occur, for example, in a lamp cord which has a broken conductor). In Canada and the United States, AFCI breakers have been required by the electrical codes for circuits feeding electrical outlets in residential bedrooms since the beginning of the 21st century; the US ''National Electrical Code'' has required them to protect most residential outlets since 2014, and the '' Canadian Electrical Code'' has since 2015. In regions using 230 V, the combination of higher voltage and lower load currents ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Arc
An electric arc (or arc discharge) is an electrical breakdown of a gas that produces a prolonged electrical discharge. The electric current, current through a normally Electrical conductance, nonconductive medium such as air produces a plasma (physics), plasma, which may produce visible light. An arc discharge is initiated either by thermionic emission or by field emission. After initiation, the arc relies on thermionic emission of electrons from the electrodes supporting the arc. An arc discharge is characterized by a lower voltage than a glow discharge. An archaic term is voltaic arc, as used in the phrase "voltaic arc lamp". Techniques for arc suppression can be used to reduce the duration or likelihood of arc formation. In the late 19th century, Arc lamp, electric arc lighting was in wide use for Street light#Arc lamps, public lighting. Some low-pressure electric arcs are used in many applications. For example, fluorescent lamp, fluorescent tubes, mercury, sodium, and met ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ground Fault Interrupter
A residual-current device (RCD), residual-current circuit breaker (RCCB) or ground fault circuit interrupter (GFCI) is an electrical safety device, more specifically a form of Earth-leakage circuit breaker, that interrupts an electrical circuit when the current passing through and neutral conductors of a circuit is not equal (the term ''residual'' relating to the imbalance), therefore indicating current leaking to ground, or to an unintended path that bypasses the protective device. The device's purpose is to reduce the severity of injury caused by an electric shock. This type of circuit interrupter cannot protect a person who touches both circuit conductors at the same time, since it then cannot distinguish normal current from that passing through a person. A residual-current circuit breaker with integrated overcurrent protection (RCBO) combines RCD protection with additional overcurrent protection into the same device. These devices are designed to quickly interrupt the pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overvoltage
In electrical engineering, overvoltage is the raising of voltage beyond the design limit of a circuit or circuit element. The conditions may be hazardous. Depending on its duration, the overvoltage event can be transient—a voltage spike—or permanent, leading to a power surge. Explanation Electronic and electrical devices are designed to operate at a certain maximum supply voltage, and considerable damage can be caused by voltage that is higher than that for which the devices are rated. For example, an electric light bulb has a wire in it that at the given rated voltage will carry a current just large enough for the wire to get very hot (giving off light and heat), but not hot enough for it to melt. The amount of current in a circuit depends on the voltage supplied: if the voltage is too high, then the wire may melt and the light bulb burn out. Similarly other electrical devices may stop working, or may even burst into flames if an overvoltage is delivered to the circ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overcurrent
In an electric power system, overcurrent or excess current is a situation where a larger than intended electric current exists through a conductor, leading to excessive generation of heat, and the risk of fire or damage to equipment. Possible causes for overcurrent include short circuits, excessive load, incorrect design, an arc fault, or a ground fault. Fuses, circuit breakers, and current limiters are commonly used overcurrent protection (OCP) mechanisms to control the risks. Circuit breakers, relays, and fuses protect circuit wiring from damage caused by overcurrent. Overcurrent in an electrical grid Overcurrent capabilities of electrical generators are essential for the power system operations. Lack of overcurrent capability (low short circuit ratio) of a weak grid creates a multitude of problems, including: * transients during the large load changes will cause large variations of the grid voltage, causing problems with the loads (e.g., some motors might not be able to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insulation Monitoring Device
An insulation monitoring device monitors the ungrounded system between an active phase conductor and earth. It is intended to give an alert (light and sound) or disconnect the power supply when the resistance between the two conductors drops below a set value, usually 50 k Ω (sample of IEC standard for medical applications). The main advantage is that the ungrounded or floating system allows a continuous operation of important consumers such as medical, chemical, military, etc. Some manufacturers of monitors for these systems are capable of handling VFDs ( Variable Frequency (Speed) Drives). Most, however are not due to issues with the DC-portions of the VFDs. Most monitors work by injecting low level DC on the line and detecting. Some manufacturers use a patented AMP-monitoring principle (Adapted Measuring Pulse) Insulation Monitoring Devices (IMD) according to IEC 61557-8 This part of IEC 61557 specifies requirements for insulation monitoring devices (IMD), which permanent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Storm
A storm is any disturbed state of the natural environment or the atmosphere of an astronomical body. It may be marked by significant disruptions to normal conditions such as strong wind, tornadoes, hail, thunder and lightning (a thunderstorm), heavy precipitation ( snowstorm, rainstorm), heavy freezing rain ( ice storm), strong winds (tropical cyclone, windstorm), wind transporting some substance through the atmosphere such as in a dust storm, among other forms of severe weather. Storms have the potential to harm lives and property via storm surge, heavy rain or snow causing flooding or road impassibility, lightning, wildfires, and vertical and horizontal wind shear. Systems with significant rainfall and duration help alleviate drought in places they move through. Heavy snowfall can allow special recreational activities to take place which would not be possible otherwise, such as skiing and snowmobiling. The English word comes from Proto-Germanic ''*sturmaz'' meaning "n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
