Earth-leakage Circuit Breaker
An earth-leakage circuit breaker (ELCB) is a safety device used in electrical installations to prevent shock. It consists of either a Electric current, current sensing mechanism, or a voltage sensing mechanism. Such a protection mechanism may be found in the form of distribution board modules, standalone devices, and special AC_power_plugs_and_sockets, sockets (aka ''receptacles''). Voltage-operated ELCBs can still be found in the wild, though these largely fell out of favour after the invention of the current-sensing based Residual-current_device, RCD (aka GFCI) technology. History Early ELCBs, first introduced about sixty years ago, were voltage operated devices (VO-ELCBs), detecting a voltage rise between installation metalwork and an external electrode. If the wrong type was used on an installation, the level of protection given could be substantially less than that intended, in particular the voltage operated type can only protect against faults or shocks to metalwork co ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
Current Transformer
A current transformer (CT) is a type of transformer that reduces or multiplies alternating current (AC), producing a current in its secondary which is proportional to the current in its primary. Current transformers, along with voltage or potential transformers, are instrument transformers, which scale the large values of voltage or current to small, standardized values that are easy to handle for measuring instruments and protective relays. Instrument transformers isolate measurement or protection circuits from the high voltage of the primary system. A current transformer presents a negligible load to the primary circuit.Donald G. Fink, H. Wayne Beatty (ed), ''Standard Handbook for Electrical Engineers, Eleventh Edition'', Mc-Graw Hill,1978, 0-07-020974-X, pp. 10-51 - 10-57 Current transformers are the current-sensing units of the power system and are used at generating stations, electrical substations, and in industrial and commercial electric power distribution. Function ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
Electric Power Distribution
Electric power distribution is the final stage in the Power delivery, delivery of electricity. Electricity is carried from the Electric power transmission, transmission system to individual consumers. Distribution Electrical substation, substations connect to the transmission system and lower the transmission voltage to medium voltage ranging between and with the use of transformers. ''Primary'' distribution lines carry this medium voltage power to distribution transformers located near the customer's premises. Distribution transformers again lower the voltage to the utilization voltage used by lighting, industrial equipment and household appliances. Often several customers are supplied from one transformer through ''secondary'' distribution lines. Commercial and residential customers are connected to the secondary distribution lines through service drops. Customers demanding a much larger amount of power may be connected directly to the primary distribution level or the subtrans ... [...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]   |
|
Nuisance
Nuisance (from archaic ''nocence'', through Fr. ''noisance'', ''nuisance'', from Lat. ''nocere'', "to hurt") is a common law tort. It means something which causes offence, annoyance, trouble or injury. A nuisance can be either public (also "common") or private. A public nuisance was defined by English scholar Sir James Fitzjames Stephen as, "an act not warranted by law, or an omission to discharge a legal duty, which act or omission obstructs or causes inconvenience or damage to the public in the exercise of rights common to all Her Majesty's subjects". ''Private nuisance'' is the interference with the right of specific people. Nuisance is one of the oldest causes of action known to the common law, with cases framed in nuisance going back almost to the beginning of recorded case law. Nuisance signifies that the "right of quiet enjoyment" is being disrupted to such a degree that a tort is being committed . Definition Under the common law, persons in possession of real prope ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
Lightning
Lightning is a natural phenomenon consisting of electrostatic discharges occurring through the atmosphere between two electrically charged regions. One or both regions are within the atmosphere, with the second region sometimes occurring on the land, ground. Following the lightning, the regions become partially or wholly electrically neutralized. Lightning involves a near-instantaneous release of energy on a scale averaging between 200 megajoules and 7 gigajoules. The air around the lightning flash rapidly heats to temperatures of about . There is an emission of electromagnetic radiation across a wide range of wavelengths, some visible as a bright flash. Lightning also causes thunder, a sound from the shock wave which develops as heated gases in the vicinity of the discharge experience a sudden increase in pressure. The most common occurrence of a lightning event is known as a thunderstorm, though they can also commonly occur in other types of energetic weather systems, such ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
Metalwork
Metalworking is the process of shaping and reshaping metals in order to create useful objects, parts, assemblies, and large scale structures. As a term, it covers a wide and diverse range of processes, skills, and tools for producing objects on every scale: from huge ships, buildings, and bridges, down to precise engine parts and delicate jewellery. The historical roots of metalworking predate recorded history; its use spans cultures, civilizations and millennia. It has evolved from shaping soft, native metals like gold with simple hand tools, through the smelting of ores and hot forging of harder metals like iron, up to and including highly technical modern processes such as machining and welding. It has been used as an industry, a driver of trade, individual hobbies, and in the creation of art; it can be regarded as both a science and a craft. Modern metalworking processes, though diverse and specialized, can be categorized into one of three broad areas known as forming, cuttin ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
Soil
Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by restricting the former term specifically to displaced soil. Soil consists of a solid collection of minerals and organic matter (the soil matrix), as well as a porous phase that holds gases (the soil atmosphere) and water (the soil solution). Accordingly, soil is a three- state system of solids, liquids, and gases. Soil is a product of several factors: the influence of climate, relief (elevation, orientation, and slope of terrain), organisms, and the soil's parent materials (original minerals) interacting over time. It continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering with associated erosion. Given its complexity and strong internal connectedness, soil ecologists ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
Home Appliance
A home appliance, also referred to as a domestic appliance, an electric appliance or a household appliance, is a machine which assists in household functions such as cooking, cleaning and food preservation. The domestic application attached to home appliance is tied to the definition of appliance as "an instrument or device designed for a particular use or function". ''Collins English Dictionary'' defines "home appliance" as: "devices or machines, usually electrical, that are in your home and which you use to do jobs such as cleaning or cooking". The broad usage allows for nearly any device intended for domestic use to be a home appliance, including consumer electronics as well as stoves, refrigerators, toasters and air conditioners. The development of self-contained electric and gas-powered appliances, an American innovation, emerged in the early 20th century. This evolution is linked to the decline of full-time domestic servants and desire to reduce household chores, allowing ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
Metal
A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated with having electrons available at the Fermi level, as against nonmetallic materials which do not. Metals are typically ductile (can be drawn into a wire) and malleable (can be shaped via hammering or pressing). A metal may be a chemical element such as iron; an alloy such as stainless steel; or a molecular compound such as polythiazyl, polymeric sulfur nitride. The general science of metals is called metallurgy, a subtopic of materials science; aspects of the electronic and thermal properties are also within the scope of condensed matter physics and solid-state chemistry, it is a multidisciplinary topic. In colloquial use materials such as steel alloys are referred to as metals, while others such as polymers, wood or ceramics are nonmetallic ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
Failure
Failure is the social concept of not meeting a desirable or intended objective, and is usually viewed as the opposite of success. The criteria for failure depends on context, and may be relative to a particular observer or belief system. One person might consider a failure what another person considers a success, particularly in cases of direct competition or a zero-sum game. Similarly, the degree of success or failure in a situation may be differently viewed by distinct observers or participants, such that a situation that one considers to be a failure, another might consider to be a success, a qualified success or a neutral situation. It may also be difficult or impossible to ascertain whether a situation meets criteria for failure or success due to ambiguous or ill-defined definition of those criteria. Finding useful and effective criteria or heuristics to judge the success or failure of a situation may itself be a significant task. Sociology Cultural historian Scot ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
Resistor
A resistor is a passive two-terminal electronic component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power resistors that can dissipate many watts of electrical power as heat may be used as part of motor controls, in power distribution systems, or as test loads for generators. Fixed resistors have resistances that only change slightly with temperature, time or operating voltage. Variable resistors can be used to adjust circuit elements (such as a volume control or a lamp dimmer), or as sensing devices for heat, light, humidity, force, or chemical activity. Resistors are common elements of electrical networks and electronic circuits and are ubiquitous in electronic equipment. Practical resistors as discrete components can be composed of various compounds and forms. Resisto ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |