Applications of Eddy Current

What are the applications of eddy current? Here in this article we are discussing about the various applications of eddy current with its disadvantage and method of minimizing the eddy current. Eddy current are useful in many ways though they have some disadvantages too. Some of the important applications of eddy currents are: Electromagnetic Damping This is used in designing dead beat galvanometers. When a steady current is passed through the coil of galvanometer, it is deflected. Normally, the coil oscillates about its equilibrium position for some time before coming…

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EDDY CURRENTS AND EDDY CURRENT LOSSES

EDDY CURRENTS AND EDDY CURRENT LOSSES We have seen whenever the flux, linking with a closed electric changes, an emf is induced in the circuit and a current flows, the value of which depends on the emf around the circuit and the resistance of the circuit. It is not necessary that the circuit be a wire and that tha flux passes entirely through it. If a solid block itself, which are linked by the flux, will carry current.If the magnetic circuit is made up of iron and if the flux…

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EFFECTS OF SELF INDUCTION A DC CIRCUIT

EFFECTS OF SELF INDUCTION IN A DC CIRCUIT In case of non-inductive coil, when a pd of V volts is applied across it, current immediately attains the value of V/R amperes, when R is the resistance of the coil, because magnetic field is not set up due ti flow of current in such a coil, so there is no self induced emf which may oppose the applied voltage V. But in case of an inductive coil, when potential difference  of V volts is applied across it, current starts rising, but…

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Energy Stored in a Magnetic Field

ENERGY STORED IN MAGNETIC FIELD When a coil is connected to an electric source, the current flowing in the circuit gradually increases from zero to its final value, and a magnetic field is established. Consequently, a portion of the electrical energy supplied by the electric source is stored as current, is dissipation from the magnetizing coil as heat. After the magnetic field has been established, and the current has attained its maximum or steady value, any more energy given to it will be dissipated as heat. In other words, no…

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Magnetic hysteresis and Magnetostriction

In this post we are going to describe magnetic hysteresis and magnetostriction separately under two different heading i.e. Magnetic Hysteresis and another is Magnetostriction. So, let’s start with magnetic hysteresis. Magnetic Hysteresis If a magnetic substance is magnetized in a strong magnetic field, it retains a considerable portion of magnetism after the magnetic force has been withdrawn. The phenomenon of lagging of magnetization or induction flux density behind the magnetizing force is known as magnetic hysteresis. Let a core of specimen of iron be wound with a number of turns of…

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Dot Convention | Inductor in Series and Parallel

DOT CONVENTION Three coils A, B and C wound on a common magnetic circuit are shown in Figure 1. Coil A has NA turns with terminals A1 and A2. The sense of winding is shown in the figure. Similarly, the coil B has NB turns with terminals B1 and B2 and coil C has NC turns with terminals C1 and C1. The terminals are marked, arbitrarily on the coils. Let us consider that a current IA enters terminal A1. Looking from top, the current encircles the core counter-clockwise. According to…

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Induced EMF | Statically and Dynamically Induced EMF

Induced e.m.f can be either dynamically induced emf or statically induced emf. in this first case, usually the field is stationary and conductors cut across it (as in d.c. generator). But in the second case, usually the conductor or the coil remains stationary and flux linked with it is changed by simply increasing or decreasing the current producing this flux (as in transformers). Let the flux linking with the coil of turns N be changed by an amount in short time dt. EMF induced, e = Rate of change of…

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Magnetic Circuit

Practically all electric power machinery (e.g. transformers, generators, motors) depend for their operation upon the magnetism produced by the magnetic circuits. The closed path followed by magnetic flux is called a magnetic circuit (Fig. 1) just as the closed path followed by current is called an electric circuit. There is a lot of similarity between the magnetic and electric circuits, and will be shown later on during discussion. A magnetic circuit consists of a structure composed for the most part of high permeability magnetic material. The presence of high permeability…

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Magnetic Field Strength Due to Various types of Conductor

Magnetic Field Strength Outside a Long Current Carrying Conductors: Consider a straight long conductor carrying current of I amperes in downward direction. Let the conductor be influenced only by the field produced by the current flowing through it (no external filed). Let the field strength at any point at a distance of r meters from the centre of the conductor due to its own filed be H newton/wb. For acting on a unit N-pole placed at this point = H newtons, tangential to the lines of force Work done in…

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Rise and Decay of Current in an Inductive Circuit

Rise of Current in an Inductive Circuit: In figure 1 is shown a resistance of R in series with a coil of self-inductance L henry, the two being put across a battery of V volt. The R-L combination becomes connected to battery when switch SW is connected to terminal ‘a’ and is short-circuited when SW is connected to ‘b’. the inductive coil is assumed to be resistance-less, its actual small resistance being included in R. When SW1 is connected to ‘a’ the R-L combination is suddenly put across the voltage…

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