Electron Articles - Page 11 of 20

When the transformer is in operation, heat is generated due to copper losses in the windings and iron losses in the core. The removal of heat from the transformer is known as cooling of the transformer.Transformer Cooling MethodsFor the dry type transformersAir Natural (AN) CoolingAir Forced (AF) or Air Blast (AB) CoolingFor oil immersed type transformersOil Natural Air Natural (ONAN) CoolingOil Natural Air Forced (ONAF) CoolingOil Forced Air Forced (OFAF) CoolingOil Forced Water Forced (OFWF) CoolingAir Natural (AN) CoolingThe air natural (AN) cooling is used in dry type, self-cooled transformers. In this method, the natural circulation of surrounding air is ... Read More

Magnetic Leakage or Leakage FluxThe part of magnetic flux that does not follow the desired path in a magnetic circuit is known as leakage flux.In most of practical magnetic circuits, the path of a large part of the magnetic flux is through iron part of the magnetic circuit and the rest part of magnetic flux flows through air. The magnetic flux in the air gap is known as useful flux $(\varphi_{g})$ since it can be used for various useful purposes.Consider a magnetic circuit having an iron core with a coil wound on it and having a narrow air gap. The ... Read More

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

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

Induced EMFWhen a magnetic flux linking a conductor or coil changes, an electromotive force (EMF) is induced in the conductor or coil, is known as induced EMF. Depending upon the way of bringing the change in magnetic flux, the induced EMF is of two types −Statically Induced EMFDynamically Induced EMFStatically Induced EMFWhen the conductor is stationary and the magnetic field is changing, the induced EMF in such a way is known as statically induced EMF (as in a transformer). It is so called because the EMF is induced in a conductor which is stationary. The statically induced EMF can also ... Read More