An electrical insulator is a material in which electric current does not flow freely. The atoms of the insulator have tightly bound electrons which cannot readily move. Other materials—semiconductors and conductors—conduct electric current more easily. The property that distinguishes an insulator is its resistivity; insulators have higher resistivity than semiconductors or conductors. The most common examples are non-metals.
In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge in one or more directions. Materials made of metal are common electrical conductors. The flow of negatively charged electrons generates electric current, positively charged holes, and positive or negative ions in some cases.
A circuit breaker is an electrical safety device designed to protect an electrical circuit from damage caused by current in excess of that which the equipment can safely carry (overcurrent). Its basic function is to interrupt current flow to protect equipment and to prevent fire. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset to resume normal operation.
A substation is a part of an electrical generation, transmission, and distribution system. Substations transform voltage from high to low, or the reverse, or perform any of several other important functions. Between the generating station and consumer, electric power may flow through several substations at different voltage levels. A substation may include transformers to change voltage levels between high transmission voltages and lower distribution voltages, or at the interconnection of two different transmission voltages. They are a common component of the infrastructure. There are 55,000 substations in the United States.
A distribution board is a component of an electricity supply system that divides an electrical power feed into subsidiary circuits while providing a protective fuse or circuit breaker for each circuit in a common enclosure. Normally, a main switch, and in recent boards, one or more residual-current devices (RCDs) or residual current breakers with overcurrent protection (RCBOs) are also incorporated.
An electric switchboard is a piece of equipment that distributes electric power from one or more sources of supply to several smaller load circuits. It is an assembly of one or more panels, each of which contains switching devices for the protection and control of circuits fed from the switchboard. Several manufacturers make switchboards used in industry, commercial buildings, telecommunication facilities, oil and gas plants, data centers, health care, and other buildings, and onboard large ships. A switchboard is divided into different interconnected sections, generally consisting of a main section and a distribution section. These two sections are sometimes replaced by a combination section, which is a section that can fulfill the roles of both of the aforementioned sections. Switchboards can also sometimes come with an auxiliary section that is used to house devices that cannot be housed in the same section as other devices.
Electrical wiring is an electrical installation of cabling and associated devices such as switches, distribution boards, sockets, and light fittings in a structure.
A current transformer (CT) is a type of transformer that is used to reduce or multiply an alternating current (AC). It produces a current in its secondary which is proportional to the current in its primary.
A power cable is an electrical cable, an assembly of one or more electrical conductors, usually held together with an overall sheath. The assembly is used for transmission of electrical power. Power cables may be installed as permanent wiring within buildings, buried in the ground, run overhead, or exposed. Power cables that are bundled inside thermoplastic sheathing and that are intended to be run inside a building are known as NM-B.
In an electric power system, a switchgear is composed of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults downstream. This type of equipment is directly linked to the reliability of the electricity supply.
Ampacity is a portmanteau for ampere capacity, defined by United States National Electrical Codes. Ampacity is defined as the maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
In electric power, a bushing is a hollow electrical insulator that allows an electrical conductor to pass safely through a conducting barrier such as the case of a transformer or circuit breaker without making electrical contact with it. Bushings are typically made from porcelain, though other insulating materials are also used.
Magnet wire or enameled wire is a copper or aluminium wire coated with a very thin layer of insulation. It is used in the construction of transformers, inductors, motors, generators, speakers, hard disk head actuators, electromagnets, electric guitar pickups, and other applications that require tight coils of insulated wire.
In electrical engineering, isolated-phase bus (IPB), also known as phase-isolated bus (PIB) in some countries, is a method of construction for circuits carrying very large currents, typically between a generator and its step-up transformer in a steam or large hydroelectric power plant.
In electrical power distribution, armoured cable usually means steel wire armoured cable (SWA) which is a hard-wearing power cable designed for the supply of mains electricity. It is one of a number of armoured electrical cables – which include 11 kV Cable and 33 kV Cable – and is found in underground systems, power networks and cable ducting.
Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820s. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor.
In electric power distribution, a bus duct typically uses sheet metal, welded metal or cast resin to contain and isolate copper or aluminium busbars for the purpose of conducting a substantial current of electricity. It is an alternative means of conducting electricity to power cables or cable bus.
Electrical busbar systems are a modular approach to electrical wiring, where instead of a standard cable wiring to every single electrical device, the electrical devices are mounted onto an adapter which is directly fitted to a current carrying busbar. This modular approach is used in distribution boards, automation panels and other kinds of installation in an electrical enclosure.
