What is a Smart Grid?A smart grid is a digitally enabled electrical grid that collects, distributes and works on the information about the behaviour of all suppliers and consumers in order to improve the efficiency, reliability and sustainability of electricity service.Smart Grid = Information Technology + Electrical GridThe smart grid uses a two-way digital communication of technologies and computer processing which enables electricity industry to better manage energy delivery and transmission. It is capable of providing real time information and enable the nearby quick balancing of supply and demand.How does a Smart Grid Work?In addition to the traditional grid’s generating ... Read More

A singly-excited system is type of excitation system used in electromechanical energy conversion which requires only one coil to produce the magnetic field. In the singly-excited system, there is only one set of electrical input terminals and one set of mechanical output terminals. The examples of singly-excited system are electromagnetic relay, hysteresis motor, solenoid valve etc.In a singly excited system, a coil is wound around a magnetic core and is connected to a voltage source so that it produces a magnetic field. Due to this magnetic field, the rotor which is made up of ferromagnetic material, experiences a torque urging ... Read More

A DC generator is an electrical machine which converts mechanical energy into DC electrical energy. DC generators are classified into two types on the basis of their methods of field excitation as follows −Separately Excited DC GeneratorSelf-Excited DC GeneratorSeparately Excited DC GeneratorA separately excited DC generator is the one whose field winding is supplied by an independent external DC source (like a battery). The magnitude of generated voltage depends upon the speed of rotation of armature and the field current, i.e., greater the speed and the field current, higher is the generated voltage. In practice, the separately excited DC generators ... Read More

AC generators are commonly known as synchronous generators or alternators which convert mechanical power into AC power. The term alternator is used for AC generator because it produces AC power. Also, it is called synchronous generator because it must be driven at a constant speed (equal to synchronous speed) to generate AC power of the desired frequency.In general, two types of AC generators are used in practice −Single Phase AC GeneratorThree Phase AC GeneratorSingle Phase AC GeneratorA single phase AC generator is an electric machine that converts mechanical power into 1- phase electric power (AC) through the process of electromagnetic ... Read More

A device which converts electrical energy into mechanical energy or mechanical energy into electrical energy is known as electromechanical energy conversion device.The electromechanical energy conversion takes place through the medium of a magnetic field. The magnetic field is used as a coupling medium between electrical and mechanical systems. It is because the energy storing capacity of a magnetic field is very high. Therefore, an electromechanical energy converter has three main parts −Mechanical systemCoupling mediumElectrical systemThe electromechanical energy converters are of two types −Gross-motion devices − Such as electrical motors or generators.Incremental motion devices − Such as microphones, loudspeakers, electromagnetic relays ... Read More

When the EMF is induced by self and mutual inductance occur simultaneously, the relative polarities of these two induced EMFs must be determined before making any circuit calculations. The induced EMF in a coil due to mutual inductance may either aid or oppose the induced EMF due to self-inductance depending upon the sense of the windings and the directions of the currents in the coils.Dot Notation or Dot RuleThe dot rule or dot convention may be stated as follows −If both currents enter the dotted ends of the coupled coils or if both currents enter undotted ends, then the sign ... Read More

B-H Curve or Magnetisation CurveThe B-H curve or magnetisation curve is the graph plotted between magnetic flux density (B) and magnetising force (H). The B-H curve indicates the manner in which the magnetic flux density varies with the change in magnetising force.The following figure shows the general shape of B-H curve of a magnetic material. The nonlinearity of the curve shows that the relative permeability μr of a magnetic material is not constant but varies depending upon the magnetic flux density.Magnetic HysteresisThe phenomenon of lagging of magnetic flux density (B) behind the magnetising force (H) in a magnetic material subjected ... Read More

B-H Curve or Magnetisation CurveThe B-H curve or magnetisation curve is the graph plotted between magnetic flux density (B) and magnetising force (H). The B-H curve indicates the manner in which the magnetic flux density varies with the change in magnetising force.The following figure shows the general shape of B-H curve of a magnetic material. The nonlinearity of the curve shows that the relative permeability $μ_{r}$ of a magnetic material is not constant but varies depending upon the magnetic flux density.Magnetic HysteresisThe phenomenon of lagging of magnetic flux density (B) behind the magnetising force (H) in a magnetic material subjected ... Read More

Magnetic CircuitA magnetic circuit is defined as a closed path followed by the magnetic flux.A magnetic circuit consists of a core of materials having high permeability like iron, soft steel etc. It is because these materials offer very small opposition to the flow of magnetic flux.Consider a coil of N turns wound on an iron core (see the figure). When an electric current I is passes through the coil, magnetic flux (ψ) is set up in the core. This magnetic flux follows a closed path ABCDA and hence ABCDA is the magnetic circuit.In a magnetic circuit, the amount of magnetic ... Read More

When two inductors are joined end to end i.e. finishing end of one joined to the starting end of the other and same current flows through both the inductors, then the inductors are said to be connected in series.Inductors in Series with No Mutual InductanceConsider two inductors of inductance $L_{1}$ and $L_{2}$ connected in series (see the figure). Assume that the mutual inductance between the two coils is zero. Let $L_{T}$ being the total equivalent inductance of the series connected inductors.Suppose at any instant the current is changing at the rate of di/dt. The total induced emf in the circuit ... Read More