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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] |
Arc Fault Circuit Interrupter
Arc may refer to: Mathematics * Arc (geometry), a segment of a differentiable curve ** Circular arc, a segment of a circle * Arc (topology), a segment of a path * Arc length, the distance between two points along a section of a curve * Arc (projective geometry), a particular type of set of points of a projective plane * arc (function prefix) (arcus), a prefix for inverse trigonometric functions * Directed arc, a directed edge in graph theory * Minute and second of arc, a unit of angular measurement equal to 1/60 of one degree. *Wild arc, a concept from geometric topology Science and technology Geology * Arc, in geology a mountain chain configured as an arc due to a common orogeny along a plate margin or the effect of back-arc extension ** Hellenic arc, the arc of islands positioned over the Hellenic Trench in the Aegean Sea off Greece * Back-arc basin, a subsided region caused by back-arc extension * Back-arc region, the region created by back-arc extension, containing all the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Residual-current Device
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Power Systems Components
Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others. The presence of either a positive or negative electric charge produces an electric field. The motion of electric charges is an electric current and produces a magnetic field. In most applications, Coulomb's law determines the force acting on an electric charge. Electric potential is the work done to move an electric charge from one point to another within an electric field, typically measured in volts. Electricity plays a central role in many modern technologies, serving in electric power where electric current is used to energise equipment, and in electronics dealing with electrica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Underwriters Laboratory
The UL enterprise is a global private safety company headquartered in Northbrook, Illinois, composed of three organizations, UL Research Institutes, UL Standards & Engagement and UL Solutions. Established in 1894, the UL enterprise was founded as the Underwriters' Electrical Bureau (a bureau of the National Board of Fire Underwriters), and was known throughout the 20th century as Underwriters Laboratories. On January 1, 2012, Underwriters Laboratories became the parent company of a for-profit company in the U.S. named UL LLC, a limited liability company, which took over the product testing and certification business. On June 26, 2022, the companies rebranded into three distinct organizations that make up the UL enterprise. The company is one of several companies approved to perform safety testing by the U.S. federal agency Occupational Safety and Health Administration (OSHA). OSHA maintains a list of approved testing laboratories, which are known as Nationally Recognized Testin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Line Communication
Power-line communication (PLC) is the carrying of data on a conductor (the ''power-line carrier'') that is also used simultaneously for AC electric power transmission or electric power distribution to consumers. A wide range of power-line communication technologies are needed for different applications, ranging from home automation to Internet access, which is often called broadband over power lines (BPL). Most PLC technologies limit themselves to one type of wires (such as premises wiring within a single building), but some can cross between two levels (for example, both the distribution network and premises wiring). Typically transformers prevent propagating the signal, which requires multiple technologies to form very large networks. Various data rates and frequencies are used in different situations. A number of difficult technical problems are common between wireless and power-line communication, notably those of spread spectrum radio signals operating in a crowded envi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromechanical Relay
A relay Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts An automotive-style miniature relay with the dust cover taken off A relay is an electrically operated switch. It has a set of input terminals for one or more control signals, and a set of operating contact terminals. The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof. Relays are used to control a circuit by an independent low-power signal and to control several circuits by one signal. They were first used in long-distance telegraph circuits as signal repeaters that transmit a refreshed copy of the incoming signal onto another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations. The traditional electromechanical relay uses an electromagnet to close or open the contacts, but relays using other operatin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Split Phase
A split-phase or single-phase three-wire system is a type of single-phase electric power distribution. It is the alternating current (AC) equivalent of the original Edison Machine Works three-wire direct-current system. Its primary advantage is that, for a given capacity of a distribution system, it saves conductor material over a single-ended single-phase system. The system is common in North America for residential and light commercial applications. Two AC lines are supplied to the premises that are out of phase by 180 degrees with each other (when both measured with respect to the neutral), along with a common neutral. The neutral conductor is connected to ground at the transformer center tap. Circuits for lighting and small appliance power outlets use circuits connected between one line and neutral. High-demand applications, such as ovens, are often powered using AC circuits—these are connected between the two AC lines. These loads are either hard-wired or use outlet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Resistance Connection
A high-resistance connection (HRC) is a hazard that results from loose or poor connections in traditional electrical accessories and switchgear which can cause heat to develop, capable of starting a fire. Glowing connections occur when relatively high current exists in a relatively large resistance object. Heat comes from power dissipation. This energy, when dissipated in a small junction area, can generate temperatures above 1000 °C (1800 °F) and can ignite most flammable materials. An example extract from the National Union of Teachers (NUT) Fire Safety Brief: :* Electrical equipment should be regularly maintained by competent people. Machines should not be allowed to overheat. Care should be taken not to cover machines while they are switched on as this is particularly likely to cause overheating. Trailing cables should be regularly checked for damage. Loose or poor connections in traditional electrical accessories and switchgear can cause heat to develop capa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citizens Band Radio
Citizens band radio (CB radio) is a land mobile radio system, a system allowing short-distance one-to-many bidirectional voice communication among individuals, using two-way radios operating near 27 MHz (or the 11-m wavelength) in the high frequency or shortwave band. Citizens band is distinct from other personal radio service allocations such as FRS, GMRS, MURS, UHF CB and the Amateur Radio Service ( "ham" radio). In many countries, CB operation does not require a license and may be used for business or personal communications. Like many other land mobile radio services, multiple radios in a local area share a single frequency channel, but only one can transmit at a time. The radio is normally in receive mode to receive transmissions of other radios on the channel; when users want to communicate they press a "push to talk" button on their radio, which turns on their transmitter. Users on a channel must take turns transmitting. In the US and Canada, and in the EU and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amateur Radio
Amateur radio, also known as ham radio, is the use of the radio frequency radio spectrum, spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency, emergency communications. The term ''"radio amateur"'' is used to specify ''"a duly authorized person interested in radioelectric practice with a purely personal aim and without wikt:pecuniary, pecuniary interest"'' (either direct monetary or other similar reward); and to differentiate it from commercial broadcasting, public safety (police and fire), or two-way radio professional services (maritime, aviation, taxis, etc.). The amateur radio service (''amateur service'' and ''amateur-satellite service'') is established by the International Telecommunication Union (ITU) through their recommended radio regulations. National governments regulate technical and operational characteristics of transmissions and issue individual station li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shortwave Radio
Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the High frequency, high frequency band (HF), which extends from 3 to 30 MHz (approximately 100 to 10 metres in wavelength). It lies between the Medium frequency, medium frequency band (MF) and the bottom of the Very high frequency, VHF band. Radio waves in the shortwave band can be reflected or refracted from a layer of electrically charged atoms in the atmosphere called the ionosphere. Therefore, short waves directed at an angle into the sky can be reflected back to Earth at great distances, beyond the horizon. This is called skywave or "skip" radio propagation, propagation. Thus shortwave radio can be used for communication over very long distances, in contrast to radio waves of higher frequency, which travel in straight lines (line-of-sight propagation) and are generally limited by the visual horizon, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
