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The process of slowly turning the turbine-generator shaft to prevent bowing while it is still hot after shutdown Typically, barring is achieved using turning gear, a small electric motor and gearbox connected to the generator shaft. Early in the history of power plants, barring was done by operators turning the shaft with a bar.
Centralised energy sources are large power plants that produce huge amounts of electricity to a large number of consumers. Most power plants used in centralised generation are thermal power plants meaning that they use a fuel to heat steam to produce a pressurised gas which in turn spins a turbine and generates electricity. This is the ...
In a power outage, the microgrid controller disconnects the local circuit from the grid on a dedicated switch and forces any online distributed generators to power the local load. [3] [4] Unintentional islanding is a dangerous condition that may induce severe stress on the generator, as the generator must match any changes in electrical load alone
A magnetohydrodynamic generator directly extracts electric power from moving hot gases through a magnetic field, without the use of rotating electromagnetic machinery. MHD generators were originally developed because the output of a plasma MHD generator is a flame, well able to heat the boilers of a steam power plant. The first practical design ...
The bearings have to be leak-tight. A hermetic seal, usually a liquid seal, is employed; a turbine oil at pressure higher than the hydrogen inside is typically used. A metal, e.g. brass, ring is pressed by springs onto the generator shaft, the oil is forced under pressure between the ring and the shaft; part of the oil flows into the hydrogen side of the generator, another part to the air side.
Water usage is one of the main environmental impacts of electricity generation. [7] All thermal power plants (coal, natural gas, nuclear, geothermal, and biomass) use water as a cooling fluid to drive the thermodynamic cycles that allow electricity to be extracted from heat energy.
With pondage, water is usually stored during periods of low electricity demand and hours when the power plant is inactive, enabling its use as a peaking power plant in dry seasons and a base load power plant during wet seasons. [1] Ample pondage allows a power plant to meet hourly load fluctuations for a period of a week or more. [2] [3]
The efficiency of a conventional steam–electric power plant, defined as energy produced by the plant divided by the heating value of the fuel consumed by it, is typically 33 to 48%, limited as all heat engines are by the laws of thermodynamics (See: Carnot cycle). The rest of the energy must leave the plant in the form of heat.