File Name: substation equipment and their functions .zip
The electricity substation is a network of electrical equipment which is connected in a structured way in order to supply electricity to end consumers. The power system is having numerous ingredients such as distribution, transmission, and generation systems and Substations act as a necessary ingredient for operations of the power system. The substations are entities from which consumers are getting their electrical supply to run their loads while required power quality can be delivered to the customers by changing frequency and voltage levels etc.. The electricity substation designs are purely dependent on the need, for instance, a single bus or complex bus system etc.
Electric power flows through several substations between generating plant and consumer changing the voltage level in several stages. A substation that has a step-up transformer increases the voltage with decreasing current, while a step-down transformer decreases the voltage with increasing the current for domestic and commercial distribution. The word substation comes from the days before the distribution system became a grid. At first substations were connected to only one power station where the generator was housed and were subsidiaries of that power station.
Elements of SubstationSubstations 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 re-closer circuit breakers or fuses for protection of branch circuits. A typical substation will contain line termination structures, high-voltage switchgear, one or more power transformers, low voltage switchgear, surge protection, controls, grounding earthing system, and metering.
Other devices such as power factor correction capacitors and voltage regulators may also be located at a substation. 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, to protect switchgear from extreme climate or pollution conditions. Types of SubstationSubstations are of three types.
They are: a b Distribution SubstationA distribution substation transfers power from the transmission system to the distribution system of an area. It is uneconomical to directly connect electricity consumers to the high-voltage main transmission network, unless they use large amounts of power. So the distribution station reduces voltage to a value suitable for local distribution.
The input for a distribution substation is typically at least two transmission or sub transmission lines. Input voltage may be, for example, KV or whatever is common in the area. Distribution voltages are typically medium voltage, between 33 and 66 kV depending on the size of the area served and the practices of the local utility. Besides changing the voltage, the job of the distribution substation is to isolate faults in either the transmission or distribution systems.
It somewhat resembles a distribution substation although power flow is in the opposite direction. Usually for economy of construction the collector system operates around 35 KV, and the collector substation steps up voltage to a transmission voltage for the grid.
The collector substation also provides power factor correction, metering and control of the wind farm. Substation Transformer Type a Step-Up Transmission SubstationA step-up transmission substation receives electric power from a near by generating facility and uses a large power transformer to increase the voltage for transmission to distant locations.
There can also be a tap on the incoming power feed from the generation plant to provide electric power to operate equipment in the generation plant.
They connect different parts of a grid and are a source for sub transmission lines or distribution lines. General ConsiderationsThe general considerations regarding the substation that are discussed are functions,design and different layouts of the substation.
To Change voltage from one level to another. To Regulate voltage to compensate for system voltage changes. To Switch transmission and distribution circuits into and out of the grid system. To Make interconnections between the electric systems of more than one utility. 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.
Selection of the location of a substation must consider many factors. Sufficient land area is required for installation of equipment with necessary clearances for electrical safety and for access to maintain large apparatus such as transformers. Where land is costly such as in urban areas, gas insulated switchgear may save money overall.
The site must have room for expansion due to load growth or planned transmission additions. Environmental effects of the substation must be considered such as drainage, noise and road traffic effects.
Grounding earthing and ground potential rise must be calculated to protect passers-by during a short-circuit in the transmission system. And of course, the substation site must be reasonably central to the distribution area to be served. This design also places minimum reliance on signaling for satisfactory operation of protection. Additionally there is the facility to support the economical operation of future feeder bays.
Fig 2. Each circuit is protected by its own circuit breaker and hence plant outage does not necessarily result in loss of supply. A fault on the feeder or transformer circuit breaker causes loss of the transformer and feeder circuit, one of which may be restored after isolating the faulty circuit breaker. A fault on the bus section circuit breaker causes complete shutdown of the substation. All circuits may be restored after isolating the faulty circuit breaker. A bus-bar fault causes loss of one transformer and one feeder.
Maintenance of one bus-bar section or isolator will cause the temporary outage of two circuits. Maintenance of a feeder or transformer circuit breaker involves loss of the circuit. Operation of two circuit breakers is required to connect or disconnect a circuit, and disconnection involves opening of a mesh. Circuit breakers may be maintained without loss of supply or protection, and no additional bypass facilities are required. Bus-bar faults will only cause the loss of one circuit breaker.
Breaker faults will involve the loss of a maximum of two circuits. Generally, not more than twice as many outgoing circuits as infeeds are used in order to rationalise circuit equipment load capabilities and rating.
Mesh substation Layout a Principle of Substation LayoutsSubstation layout consists essentially in arranging a number of switchgear components in an ordered pattern governed by their function and rules of spatial separation. Earth Clearance: This is the clearance between live parts and earthed structures, walls, screens and ground.
Phase Clearance: This is the clearance between live parts of different phases. Isolating Distance: This is the clearance between the terminals of an isolator and the connections. Section Clearance: This is the clearance between live parts and the terminals of a work section. The limits of this work section, or maintenance zone, may be the ground or a platform from which the man works. The provision of a section clearance ii. Use of an intervening earthed barrierThe choice between the two methods depends on the voltage and whether horizontal or vertical clearances are involved.
A section clearance is composed of the reach of a man taken as 8 feet plus an earth clearance. For the voltage at which the earth clearance is 8 feet the space required will be the same whether a section clearance or an earthed barrier is used. MaintenanceMaintenance plays a major role in increasing the efficiency and decreasing the breakdown. The rules and basic principle are discussed.
For vertical clearances it is necessary to take into account the space occupied by the equipment and the need for an access platform at higher voltages.
The height of the platform is taken as 1. Maintenance is done through two ways:a By Establishing Maintenance Zones. There should be a means of isolation on each side of the circuit breaker, and to separate it from adjacent live parts when isolated either by section clearances or earth barriers b Electrical SeparationsTogether with maintenance zoning, the separation, by isolating distance and phase clearances, of the substation components and of the conductors interconnecting them constitute the main basis of substation layouts.
There are at least three such electrical separations per phase that are needed in a circuit:i. Between the terminals of the bus bar isolator and their connections. Between the terminals of the circuit breaker and their connections.
Between the terminals of the feeder isolator and their connections. IntroductionWe are going to discuss about the line diagram and number of feeders of KV substation and the voltage that has been transmitted to other substations and inter connection of KV line and also about the lines that feeds this substation from generating units.
Line diagram:In power engineering, a one-line diagram or single-line diagram is a simplified notation for representing a three-phase power system. The interconnection of KV Grid Substations FeedersFeeder circuits are the connections between the output terminals of a distribution substation and the input terminals of primary circuits.
The distribution feeder circuit conductors leave the substation from a circuit breaker via underground cables, called substation exit cables. The underground cables connect to a nearby overhead primary circuit outside the substation. This eliminates multiple circuits on the poles adjacent to the substations there by improving the overall appearance of the substation.
They are 12 feeders of KV which are basically collector substation and it has 16 feeders of 33KV which are industries and for domestic user. IntroductionWe are going to discuss about the basic principle of transformer, working, construction, losses, application and the transformers used in substation and their tapping details. Except for air-core transformers, the conductors are commonly wound around a single iron-rich core, or around separate but magnetically-coupled cores.
A varying current in the primary winding creates a varying magnetic field in the core or cores of the transformer. This varying magnetic field induces a varying electromotive force EMF or voltage in the secondary winding.
This effect is called mutual induction. Firstly, an electric current can produce a magnetic field electromagnetism and secondly that a changing magnetic field within the a coil of wire induces a voltage across the ends of the coil electromagnetic induction.
Changing the current in the primary coil changes the magnitude of the magnetic field.
Premium Membership. Learn from experienced power engineers. Distribution substation is a substation from which electric supply is distributed to the different users. In a substation there are numbers of incoming and outgoing circuits each having its isolator, circuit breaker, transformers etc. Safety and protection of equipment as well as working personnel is also a considerable factor.
For transferring of electrical power from generating unit to distributing units various types of electrical equipment are required. The equipment like bus bars, isolator, power transformer etc. The main equipment required for the substation installations is explained below in details:. Lightning Arrestor is the first member of the electrical substations. It protects the substation equipment from transient high voltage and also limits the duration and amplitude of the flow of current. The Lightning arrestor is connected between line and earth, i. Power transformers are used for stepping up the voltage for transmission at generating station and for stepping down the voltage for further distribution at main step-down transformer substations.
of Substations. ▫ Substation Equipment. Substation Configurations and its Components Performs several important switching functions.
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. Substations may be owned and operated by an electrical utility, or may be owned by a large industrial or commercial customer.
Substation Protection System Pdf Currently there is no fire protection system for substation yards. Get an introduction to technical requirements, configuration philosophies, design practices, information sources and work processes.
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