Steel and Transmission of Electric Power...

Steel and Transmission of Electric Power  Transmission of electric power is a process by which the electric power produced at power plants is transported in bulk quantities over long distances for eventual use by consumers. The ultimate objective of electric power transmission is to provide power to customers economically, safely, reliably, efficiently, and with minimal environmental impact. Each of these aspects has one or more quantitative measure, such as price per kilowatt-hour, number and lethality of accidents, frequency and duration of service interruptions, generating plant heat rate, transmission and distribution losses, and emissions factors. Transmission systems are designed, and their individual components selected, with all of these objectives in mind, though they may be optimized differently in different systems. Power transmission process has got three main components (Fig 1). They are (i) substations, (ii) transmission poles and towers, and (iii) electricity conductors. Steel plays a major role in all these three components of transmitting power from the point of generation to the consumers. Fig 1 Components of power transmission process Steel use in substations Substations transform voltage from high to low, or the reverse, or perform any of several other important functions. Substation varies in size and configuration. Between the generating station and consuming point, electric power may flow through several substations at different voltage levels. A substation consists of (i) outdoor switch yard, (ii) a building which houses the control equipment, and (iii) the fencing. The outdoor switch yard has (i) structures at dead-end, (ii) static poles, and bus supports and equipment stands. It has also got the grounding arrangement. Structures at dead-end are those structures where the transmission line ends or angles off. They are typically constructed with heavier structural steels in case they are needed to carry heavier tension. The two most common dead-end...

Design Features of an AC Electric Arc Furnace Feb24

Design Features of an AC Electric Arc Furnace...

Design Features of an AC Electric Arc Furnace  Electric arc furnace (EAF) used for steel making apply high current and low voltage electric energy to the charge materials , and thereby melt and refine them. EAF is a batch furnace which consists of a refractory lined vessel covered with a retractable roof through which electrodes enter the furnace. General features of a typical AC electric arc furnace is shown in Fig 1. Fig 1 General features of an AC electric arc furnace  EAF has a large bowl shaped body with a dish shaped hearth. The shell has a refractory lining inside. The reaction chamber of the furnace is covered from above by a removable roof made of refractory bricks held by a roof ring. It is fed with a three phase alternating current (AC) and has three graphite electrodes which are connected by flexible cables and water cooled copper tubes. The design of electric arc furnaces has changed considerably in recent years. Emphasis has been placed on making furnaces larger, increasing power input rates to the furnace and increasing the speed of furnace movements in order to minimize power off time in furnace operations. Modern steel melting shops with EAFs usually employ a mezzanine furnace installation. In this type of installation, the furnace sits on an upper level above the shop floor. The furnace is supported on a platform which can take on several different configurations. In the half platform configuration, the electrode column support and roof lifting gantry is hinged to the tiltable platform during operation and tapping. When charging the furnace, the complete assembly is lifted and swiveled. This design allows for the shortest electrode arm configuration. In the full platform design, the electrode column support and roof lifting assembly is completely...

Transmission of Electric Power Mar06

Transmission of Electric Power...

Transmission of Electric Power Transmission of electric power is a process by which the electric power produced at power plants is transported in bulk quantities over long distances for eventual use by consumers. Electric power is sent from generating power plants to the end consumer by transmission lines. Transmission lines, when interconnected with each other, become transmission networks. This transmission network along with power stations and substations is known as ‘transmission grid’ or simply ‘grid’. A typical transmission grid is shown in Fig 1. The transmission networks which are interconnected at the national level are known as ‘National grid’. Energy is usually transmitted within a grid with three phase alternating current (AC). Due to the involvement of large quantity of electric power and due to the properties of electricity, transmission involving long distances normally takes place at high voltage (33 kV or above). Electric power is usually transported to a substation near the consuming point which is either a populated area or an industrial complex. At the substation, the high voltage electric power is converted to lower voltages suitable for consumer use, and then transported to the end users through low voltage electric distribution line Fig 1 Typical transmission grid Transmission efficiency and transmission losses Transmitting electricity at high voltage reduces the fraction of energy lost to resistance, which varies depending on the specific conductors, the current flowing, and the length of the transmission line. For a given amount of power, a higher voltage reduces the current and thus the resistive losses in the conductor. Transmission efficiency is improved by increasing the transmission voltage using a step-up transformer which has the effect of reducing the current in the conductors, whilst keeping the power transmitted nearly equal to the power input. The reduced current flowing through the conductor reduces the losses...