The process of heating in which a high-frequency alternating electric field or radio waves or microwave electromagnetic radiation are used to heat the dielectric materials is known as dielectric heating.Applications of Dielectric HeatingSince the dielectric heating is an expensive method of heating, therefore, it is only used where other methods of heating are not possible. Some of the applications of the dielectric heating are described as follows −Plastic IndustryThe plastic is used for making many appliances. If the pre-heating of the plastic is uniform, then the molding of plastic becomes faster and fault free. This pre-heating of the plastic is ... Read More

Induction Heating FurnaceAn electrical furnace in which the heat is produced by induction heating of metal, is called the induction heating furnace. The induction heating furnaces have the capacities range from less than 1 kg to 100 tons and are used to melt various metals like iron, copper, aluminium, etc.Vertical Core Type Induction FurnaceThe schematic diagram of the vertical core type induction furnace is shown in the figure below.The vertical core type induction furnace is also known as Ajax-Wyatt Furnace.This furnace has a vertical crucible instead of a horizontal one (as in case direct core type induction furnace) for the ... Read More

Coated ElectrodeA coated electrode is made of a metallic wire (called core wire) coated uniformly with flux material. While fluxing, the electrode about 20 mm of its length is left bare at one end for mounting it into the electrode holder. The flux material used for coating of the electrode is a bad conductor of electricity.Coated electrodes are used these days because the flux coated on the core wire is composed of special element which protects both the arc and the weld metal that passes through range of liquid action and solidification during welding.Advantages of Coated ElectrodesThe coated electrodes are ... Read More

When the two-phase AC electrical power is transmitted through the underground cables from the generating station to the consumers, then the transmission system is called the underground two-phase AC system of transmission.Depending upon the number of conductors used, the underground two-phase AC system is classified into two types viz −Two-phase three-Wire AC SystemTwo-phase four-wire AC SystemConductor Material Required in Underground Two-Phase Three-Wire AC SystemFigure-1 shows the circuit diagram of the underground two-phase three-wire AC system of electric power transmission.Let us consider that the maximum voltage between the outer conductors is $\mathit{V_{\mathit{m}}}$. Then, the maximum voltage between any one outer wire ... Read More

Underground Three Phase AC SystemWhen the three phase AC electric power is transmitted through the underground cables, then the system of electric power transmission is called the underground three phase AC system.Depending upon the number of conductors used, the underground three-phase AC system of electric power transmission is classified into two types −Three-Phase Three-Wire SystemThree-Phase Four-Wire SystemConductor Material Required in Underground Three-Phase Three-Wire SystemThe circuit diagram of the underground 3-phase 3-wire AC system is shown in Figure-1. In this system, the three line conductors are taken from the three phase windings of the alternator.Let the maximum value of voltage between ... Read More

Underground Single-Phase AC SystemThe electric transmission system which transmits the single-phase AC electric power through the underground cables is termed as the underground single-phase AC system of transmission.The underground single-phase AC system of electric power transmission is classified into three types viz. −Single-Phase Two-Wire AC SystemSingle-Phase Two-Wire AC System with Mid-Point EarthedSingle-Phase Three-Wire AC SystemThe various systems of the electric transmission require different volume of conductor material. The volume of conductor material required in the above 1-phase underground AC system is described below.Conductor Material Required in 1-Phase 2-Wire Underground AC SystemThe typical single-phase 2-wire AC underground AC system is shown ... Read More

Underground DC SystemWhen the DC electric power is transmitted from the power generating station to the consumer through the underground cables, then the electric power transmission system is called the underground DC system.The underground DC transmission system is classified into three types −Two-Wire DC SystemTwo-Wire DC System with Mid-Point EarthedThree-Wire DC SystemConductor Material Required in Underground 2-Wire DC SystemThe underground two-wire DC system is shown in Figure-1. It has two conductors taken from the generator terminals.Let, 𝑉𝑚 = Maximum voltage between conductors𝑃 = Power to be transmitted𝑙 = Distance for which power is transmittedThe load current is given by, $$\mathrm{\mathit{I_{\mathrm{1}}\mathrm{\, ... Read More

Suspension InsulatorThe suspension type insulator is the one which consists of a number of porcelain discs connected in series by metal links in the form of a string as shown in Figure-1.Potential Distribution over Suspension Insulator StringAs we know the string of suspension insulators consists of a number of porcelain discs connected in series through metal links. The porcelain portion of each disc is in between two metal links. Thus, the disc acts like a capacitor represented by C as shown in Figure-2.The capacitance C is called the mutual capacitance. If the string has only mutual capacitance, then the charging ... Read More

Three-Phase Transmission SystemA three-phase transmission system is the one in which three line conductors are used to transmit the AC electric power from generating station to the substations. The three-phase system is universally adopted for transmission of electric power.Depending upon the number of conductors used, the three-phase AC transmission system is classified into two types viz. −Three-Phase Three-Wire SystemThree-Phase Four-Wire SystemConductor Material Required in 3-Phase 3-Wire AC SystemConsider a three-phase three-wire AC system as shown in Figure-1, it has three line conductors and one earthed neutral wire. The three-phase three-wire system may be star connected (as shown in Figure-1) or ... Read More

Single-Phase AC Transmission SystemThe electric power transmission system in which two conductors viz. phase conductor and neutral wire are used to transmit the electric power is known as single phase AC transmission system.The single phase AC transmission system can be classified into following three types viz. −Single-phase two-wire system with one conductor earthedSingle-phase two-wire system with mid-point earthedSingle-phase three-wire systemConductor Material Required in 1-Phase 2-Wire System with One Conductor EarthedThe single phase two wire AC system with one conductor earthed is shown in Figure-1.Let, $\mathrm{Power\: transmitted\mathrm{\, =\, }\mathit{P}}$$\mathrm{Maximum \: voltage \: between\: conductors\mathrm{\, =\, }\mathit{V_{m}}}$$\mathrm{RMS\: value\: of \: voltage\mathrm{\, =\, ... Read More