A 115 kV to 41.6/12.47 kV 5000 kVA 60 Hz substation with circuit switcher, regulators, reclosers and control building An electrical substation is a subsidiary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse using transformers. Electrical Substation, Warren Minnesota The incoming 115 kV transmission line enters on the left and terminates on the A-frame structure. ...
Electrical Substation, Warren Minnesota The incoming 115 kV transmission line enters on the left and terminates on the A-frame structure. ...
For other uses, see Electricity (disambiguation). ...
Itaipu Dam is a hydroelectric generating station Electricity generation is the first process in the delivery of electricity to consumers. ...
Power line redirects here. ...
11kV/400V-230V transformer in an older suburb of Wellington, New Zealand Electricity distribution is the penultimate stage in the delivery (before retail) of electricity to end users. ...
International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ...
Figure 1:Three-phase pole-mounted step-down transformer. ...
Explanation
Transformation may take place in several stages in sequence, starting at the generating plant where the voltage is increased for transmission purposes and is then progressively reduced to the voltage required for household or industrial use. The range of voltages in a power system varies from 110 V up to 765 kV depending on the country. Electricity generation is the first process in the delivery of electricity to consumers. ...
A substation that has a step-up transformer increases the voltage while decreasing the current, while a step-down transformer decreases the voltage while increasing the current for domestic and commercial distribution. The word substation comes from the days before the distribution system became a grid. The first substations were connected to only one power station where the generator was housed, and were subsidiaries of that power station. Figure 1:Three-phase pole-mounted step-down transformer. ...
Electric current is the flow (movement) of electric charge. ...
Figure 1:Three-phase pole-mounted step-down transformer. ...
Look up grid in Wiktionary, the free dictionary. ...
For other uses, see Power station (disambiguation). ...
Substations generally contain one or more transformers, and have switching, protection and control equipment. In a large substation, circuit breakers are used to interrupt any short-circuits or overload currents that may occur on the network. Smaller distribution stations may use recloser circuit breakers or fuses for protection of branch circuits. Substations do not (usually) have generators, although a power plant may have a substation nearby. A typical substation will contain line termination structures, high-voltage switchgear, one or more power transformers, low voltage switchgear, surge protection, controls, and metering. Other devices such as power factor correction capacitors and voltage regulators may also be located at a substation. A circuit breaker is a piece of equipment which is designed to protect an electrical apparatus from damage caused by overload or short circuit. ...
Short Circuit was a 1986 comedy sci-fi film starring Ally Sheedy and Steve Guttenberg and directed by John Badham. ...
×11:28, 26 August 2007 (UTC)121. ...
Look up fuse in Wiktionary, the free dictionary. ...
A power station (also power plant) is a facility for the generation of electric power. ...
Figure 1:Three-phase pole-mounted step-down transformer. ...
Power factor correction (PFC) is a technique of counteracting the undesirable effects of electric loads that create a power factor (p. ...
See Capacitor (component) for a discussion of specific types. ...
Electronic symbol for Voltage regulator A voltage regulator is an electrical regulator designed to automatically maintain a constant voltage level. ...
Substations may be on the surface in fenced enclosures, underground, or located in special-purpose buildings. High-rise buildings may have indoor substations. Indoor substations are usually found in urban areas to reduce the noise from the transformers, for reasons of appearance, or to protect switchgear from extreme climate or pollution conditions.
Where a substation has a fence, it must be properly grounded (UK: earthed) to protect people from high voltages that may occur during a fault in the transmission system. Earth faults at a substation can cause Earth Potential Rise at the fault location. It has been suggested that Ground conductor be merged into this article or section. ...
Earth Potential Rise (EPR) also called Ground Potential Rise (GPR) occurs when a large current flows to earth through an earth grid impedance. ...
Transmission substation A transmission substation is one whose main purpose is to connect together various transmission lines.
The simplest case is where all transmission lines have the same voltage. In such cases, the substation contains high-voltage switches that allow lines to be connected together or isolated for maintenance.
Transmission substations can range from simple to complex. A small "switching station" may be little more than a bus plus some circuit breakers. The largest transmission substations can cover a large area (several acres/hectares) with multiple voltage levels, and a large amount of protection and control equipment (capacitors, relays, switches, breakers, voltage and current transformers).
Distribution substation
A distribution substation in Scarborough, Ontario, Canada disguised as a house, complete with a driveway, front walk and a mown lawn and shrubs in the front yard. A warning notice can be clearly seen on the "front door". A distribution substation is one whose main purpose is to transfer power from the transmission system to the distribution system of some area. It is uneconomical to directly connect electricity consumers to the main transmission network (unless they use large amounts of energy); so the distribution station reduces voltage to a value suitable for connection to local loads. Image File history File linksMetadata Download high-resolution version (1600x1200, 1352 KB) Summary An electrical substation in Scarborough, Ontario, Canada disguised as a house. ...
Image File history File linksMetadata Download high-resolution version (1600x1200, 1352 KB) Summary An electrical substation in Scarborough, Ontario, Canada disguised as a house. ...
Country Canada Province Ontario Established 1 January 1850 (township) 1 January 1967 (borough) Incorporated Amalgamation June 1983 (city) 1 January 1998 Government - Mayor David Miller (Toronto Mayor) - Governing Body Toronto City Council - MPs John Cannis, Jim Karygiannis, Derek Lee, John McKay, Dan McTeague, Tom Wappel - MPPs Bas Balkissoon, Lorenzo Berardinetti...
The input for a distribution substation is typically at least two transmission or subtransmission lines. Input voltage may be, for example, 115 kV, or whatever is common in the area. The output is a number of feeders. Distribution voltages are typically medium voltage, between 2.4 and 33 kV depending on the size of the area served and the practices of the local utility. The volt is the SI derived unit for electric potential and voltage (derived from the ampere and watt). ...
Feeder may refer to: Feeder (band), the British rock group Feeder (fetish), the name of a role associated with fat admirers Feeder (gaming), a term used for any one that dies in a first person shooter so many times, that the gamer feeds the other team kills Feeder, a regional...
The volt is the SI derived unit for electric potential and voltage (derived from the ampere and watt). ...
The feeders will then run overhead, along streets (or under streets, in a city) and eventually power the distribution transformers at or near the customer premises.
Besides transforming the voltage, the job of the distribution substation is to isolate faults in either the transmission or distribution systems. Distribution substations may also be the points of voltage regulation, although on long distribution circuits (several km/miles), voltage regulation equipment may also be installed along the line. In electrical engineering, particularly power engineering, voltage regulation is the ability of a system to provide near constant voltage over a wide range of load conditions. ...
Complicated distribution substations can be found in the downtown areas of large cities, with high-voltage switching, and switching and backup systems on the low-voltage side. More typical distribution substations have a switch, one transformer, and minimal facilities on the low-voltage side.
Design The main issues facing a power engineer are reliability and cost. A good design attempts to strike a balance between these two, to achieve sufficient reliability without excessive cost. The design should also allow easy expansion of the station, if required. Power Engineers work mainly around Prime Movers such as Boilers, Turbines, Steam Engines, Refrigeration Plants and all sorts of power driven devices required for moving materials and energy from one source to another. ...
Layout
Tottenham Substation, set in wild parkland in North London In the largest stations, incoming lines will almost always have a disconnect switch and a circuit breaker. In some cases, the lines will not have both; with either a switch or a circuit breaker being all that is considered necessary. These devices are used as isolation and protection devices. A disconnect switch is almost always used solely to provide isolation, due to it not being rated for breaking a loaded circuit, whilst a circuit breaker is often used both as an isolation element as well as a protection device.[clarify] Where a large fault current flows through the circuit break this may be detected through the use of current transformers. The magnitude of the current transformer outputs may be used to 'trip' the circuit breaker resulting in a disconnection of the load supplied by the circuit break from the feeding point. This seeks to isolate the fault point from the rest of the system, and allow the system to continue operating with minimal impact. Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (3264 × 2448 pixel, file size: 3. ...
Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (3264 × 2448 pixel, file size: 3. ...
A 2 pole miniature circuit breaker A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. ...
Once past the switching components, the lines of a given voltage all tie in to a common bus. This is a number of thick metal bus bars, in most cases there are three bars, since three-phase electrical power distribution is largely universal around the world. An electrical bus (sometimes spelled buss) is a physical electrical interface where many devices share the same electric connection. ...
1500 amp busbars within a power distribution rack for a large building A busbar (often pronounced buzz bar) refers in electrical power distribution to thick strips of Copper or other material that conduct electricity around a switchboard, distribution board or other electrical apparatus. ...
Three phase systems have 3 waveforms (usually carrying power) that are 2/3π radians (120 degrees,1/3 of a cycle) offset in time. ...
Substations that require additional reliability often have a double bus or even a double ring bus, in which the bus system is actually duplicated, with each feeder (and all or most outgoers) having a connection to each separate bus. Most substations will not have this, as it is mainly for reliability in substations whose failure would bring down a substantial part of the system, or whose load is of vital importance. Other compromises between a single and double bus can be found; for example, the breaker-and-a-half setup.
Once having established buses for the various voltage levels, transformers may be connected between the voltage levels. These will again have a circuit breaker, much like transmission lines, in case a transformer has a fault (commonly called a 'short circuit').
Along with this, a substation always has control circuitry needed to command the various breakers to open in case of the failure of some component.
Switching function An important function performed by a substation is switching, which is the connecting and disconnecting of transmission lines or other components to and from the system. Switching events may be "planned" or "unplanned". // Switching technologies are crucial to the new network design. ...
A transmission line or other component may need to be deenergized for maintenance or for new construction; for example, adding or removing a transmission line or a transformer.
To maintain reliability of supply, no company ever brings down its whole system for maintenance. All work to be performed, from routine testing to adding entirely new substations, must be done while keeping the whole system running.
Perhaps more importantly, a fault may develop in a transmission line or any other component. Some examples of this: a line is hit by lightning and develops an arc, or a tower is blown down by a high wind. The function of the substation is to isolate the faulted portion of the system in the shortest possible time. There are various types of faults: In document ISO/CD 10303-226, a fault is defined as an abnormal condition or defect at the component, equipment, or sub-system level which may lead to a failure. ...
Electricity arcs between the power rail and electrical pickup shoe on a London Underground train An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, similar to the instant spark, resulting from a current flowing through normally nonconductive media such as air. ...
In the United States, a tower is the part of a transmission line that holds the conductors in place and off the ground. ...
There are two main reasons: a fault tends to cause equipment damage; and it tends to destabilize the whole system. For example, a transmission line left in a faulted condition will eventually burn down, and similarly, a transformer left in a faulted condition will eventually blow up. While these are happening, the power drain makes the system more unstable. Disconnecting the faulted component, quickly, tends to minimize both of these problems. For delivered electrical power, see Electrical power industry. ...
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References and further reading - Overview of substation design and layout
- US Department of Agriculture engineering design manual for rural substations
See also
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