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Glossary - Power (ID: 18387)
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Power The following Terms and Abbreviations are standard to Matthews-Daniel but they may vary within the industry. You may search this page by clicking on the "Edit" menu in your browser and selecting "Find on this page" (or "Find in Frame" in Netscape), or by pressing Ctrl-F. TERMS Ampere The unit of measurement of electrical current produced in a circuit by 1 volt acting through a resistance of 1 ohm. Ancillary Services Those services necessary to support the transmission of energy from resources to loads while maintaining reliable operation of the Transmission Provider s transmission system in accordance with Good Utility Practice. Anthracite A hard, black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and low percentage of volatile matter. Baseload The minimum amount of electric power delivered or required over a given period of time at a steady rate. Baseload Capacity The generating equipment normally operated to serve loads on an around-the-clock basis. Baseload Plant A plant, usually housing high efficiency steam-electric units, which is normally operated to take all or part of the minimum load of a system, and which consequently produces electricity at an essentially constant rate and runs continuously. These units are operated to maximize system mechanical and thermal efficiency and minimise system operating costs. Biomass Contraction for biological mass, the amount of living material provided by a given area of the earth's surface. The term is most familiar from discussions of biomass energy, that is, the fuel energy that can be derived directly or indirectly from biological sources. Biomass energy from wood, crop residues, and dung remains the primary source of energy in developing regions. Bituminous Coal The most common coal. It is dense and black (often with well-defined bands of bright and full material). Its moisture content usually is less than 20 percent. It is used for generating electricity, making coke, and space heating. BTU (British Thermal Unit) A standard unit for measuring the quantity of heat energy equal to the quantity of heat required to raise the temperature of 1 pound of water by 1 degree Fahrenheit. Circuit Breaker Electrical device that cuts off the electric current through a circuit under abnormal conditions. Circuit breakers also provide protection against short circuits. A short circuit is caused by a contact between the neutral, or grounded, side of the electrical line and the live side of the line. Defective insulation or other parts can cause short circuits. Short circuits offer very low resistance to current, which allows large currents to flow through the circuit, sometimes melting the wires or causing a fire. Circuit breakers in the live side of the electrical line can stop short circuits by cutting the connection when the current gets too high. In some circuits, especially those that carry large currents, simply breaking the circuit is not enough to stop the flow of current. The current in some circuits is strong enough to jump, or arc, across the gap in the circuit, even after the circuit breaker has been tripped. Circuit breakers that deal with high levels of current, especially direct current, have methods of getting rid of the energy in the arc and stopping the current. In oil breakers, the design of the circuit breaker forces the arc of broken circuit through a sealed container of oil or gas. The arc heats the oil around it. The hot oil begins to circulate in the tank, carrying heat and energy away from the arc. Air-blast circuit breakers send the arc through compressed air, which is immediately released to the outside, carrying the heat and energy of the arc with it. Combined Cycle An electric generating technology in which electricity is produced from otherwise lost waste heat exiting from one more gas (combustion) turbines. The exiting heat is routed to a conventional boiler or to a heat recovery steam generator for utilization by a steam turbine in the production of electricity. This process increases the efficiency of the electric generating unit. Combined Cycle Unit An electric generating unit that consists of one or more combustion turbines and one or more heat recovery steam generators (HRSG) with a portion of the required energy input to the HRSG provided by the exhaust gas of the combustion turbine(s). Combined Pumped-Storage Plant A pumped-storage hydroelectric power plant that uses both pumped water and natural stream flow to produce electricity. Cogenerator A generating facility that produces electricity and another form of useful thermal energy (such as heat or steam) used for industrial, commercial, heating, or cooling purposes. Distribution System The portion of an electric system that is dedicated to delivering electric energy to an end user. Electric Cable Cable composed of one or more electric conductors, covered by insulation and sometimes a protective sheath, used for transmitting electric power or the impulses of an electric communications system. For electric-power transmission, three-wire cables sheathed with lead and filled with oil under pressure are employed for high-voltage circuits; secondary distribution lines usually employ insulated single-conductor cables. Flue Gas Desulphurisation Unit (Scrubber) Equipment used to remove sulphur oxides from the combustion gases of a boiler plant before discharge to the atmosphere. Chemicals, such as lime, are used as the scrubbing media. Flue Gas Particulate Collectors Equipment used to remove fly ash from the combustion gases of a boiler plant before discharge to the atmosphere. Particulate collectors include electrostatic precipitators, mechanical collectors (cyclones), fabric filters (baghouses), and wet scrubbers. Geothermal Plant A plant in which the prime mover is a steam turbine. The turbine is driven either by steam produced from hot water or by natural steam that derives its energy from heat found in rocks or fluids at various depths beneath the surface of the earth. The energy is extracted by drilling and/or pumping. Generator A machine that converts mechanical energy into electrical energy. Grid The layout of an electrical distribution system. Hydroelectric Plant A plant in which the turbine generators are driven by water. Internal Combustion Plant A plant in which the prime mover is an internal combustion engine (mainly diesel). An internal combustion engine has one or more cylinders in which the process of combustion takes place, converting energy released from the rapid burning of a fuel-air mixture into mechanical energy. Diesel or gas-fired engines are the principal types used in electric plants. The plant is usually operated during periods of high demand for electricity. Interruptible Gas Supply Gas sold to customers with a provision that permits curtailment or cessation of service at the discretion of the distributing company under certain circumstances, as specified in the service contract. Interruptible Load Refers to program activities that, in accordance with contractual arrangements, can interrupt consumer load at times of seasonal peak load by direct control of the utility system operator or by action of the consumer at the direct request of the system operator. It usually involves commercial and industrial consumers. In some instances the load reduction may be affected by direct action of the system operator (remote tripping) after notice to the consumer in accordance with contractual provisions. For example, loads that can be interrupted to fulfil planning or operation reserve requirements should be reported as Interruptible Load. Interruptible Load as defined here excludes Direct Load Control and Other Load Management. Nuclear Fuel Fissionable materials that have been enriched to such a composition that, when placed in a nuclear reactor, will support a self-sustaining fission chain reaction, producing heat in a controlled manner for process use. Nuclear Power Plant A facility in which heat produced in a reactor by the fission of nuclear fuel is used to drive a steam turbine. Outage The period during which a generating unit, transmission line, or other facility is out of service. Peak Demand The maximum load during a specified period of time. Peak Load Plant A plant usually housing old, low-efficiency steam units, gas turbines, diesels, or pumped storage hydroelectric equipment normally used during the peak-load periods. Peaking Capacity Capacity of generating equipment normally reserved for operation during the hours of highest daily, weekly, or seasonal loads. Some generating equipment may be operated at certain times as peaking capacity and at other times to serve loads on an around-the-clock basis. Plant A facility at which are located prime movers, electric generators, and auxiliary equipment for converting mechanical, chemical, and/or nuclear energy into electric energy. A plant may contain more than one type of prime mover. Pumped Storage Hydroelectric Plant A plant that usually generates electric energy during peak-load periods by using water previously pumped into an elevated storage reservoir during off-peak periods when excess generating capacity is available to do so. When additional generating capacity is needed, the water can be released from the reservoir through a conduit to turbine generators located in a power plant at a lower level. Purchased Power Adjustment A clause in a rate schedule that provides for adjustments to the bill when energy from another electric system is acquired and it varies from a specified unit base amount. Pure Pumped Storage Hydroelectric Plant A plant that produces power only from water that has previously been pumped to an upper reservoir. Running and Quick-Start Capability The net capability of generating units that carry load or have quick-start capability. In general, quick-start capability refers to generating units that can be available for load within a 30-minute period. Scheduled Outage The shutdown of a generating unit, transmission line, or other facility, for inspection or maintenance, in accordance with an advance schedule. Spinning Reserve That reserve generating capacity running at a zero load and synchronized to the electric system. Solar Energy Photovoltaic cells are a means of directly converting radiation from the sun into electricity. These cells, made from thin slices of semiconductor materials, appear to produce significant amounts of energy at little cost. Transformer An electrical device for changing the voltage of alternating current. Transmission The movement or transfer of electric energy over an interconnected group of lines and associated equipment between points of supply and points at which it is transformed for delivery to consumers, or is delivered to other electric systems. Transmission is considered to end when the energy is transformed for distribution to the consumer. Transmission System (Electric) An interconnected group of electric transmission lines and associated equipment for moving or transferring electric energy in bulk between points of supply and points at which it is transformed for delivery over the distribution system lines to consumers, or is delivered to other electric systems. Turbine A machine for generating rotary mechanical power from the energy of a stream of fluid (such as water, steam, or hot gas). Turbines convert the kinetic energy of fluids to mechanical energy through the principles of impulse and reaction, or a mixture of the two. Wind Energy Energy contained in the force of the winds blowing across the earth s surface by connecting a spinning rotor (an assembly of blades attached to a hub) to an electric generator, modern wind turbines convert wind energy, which turns the rotor, into electrical energy. ABBREVIATIONS ABWR Advanced Boiling Water Reactor BOM Build Own Maintain BOOM Build, Own, Operate And Maintain BWR Boiling Water Reactor CT Current Transformer ECA Energy Conversion Agreement FBR Fast Breeder Reactor GIS Gas Insulated Switchgear IGCC Integrated Gasification Combined Cycle IPP Independent Power Plant OFAF Oil Forced and Air Forced PPA Power Purchase Agreement PT Potential Transformer PWR Pressurised Water Reactor SCADA Supervisory, Control and Data Acquisition XPLE Cross Linked Polyethylene Glossary - Power