What is eddy current PDF?

Abstract. Eddy currents (also called Foucault's currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction. Also, circulating currents (eddy currents) are induced in bulk pieces of metal moving through a magnetic field.

What are eddy currents?

The minor application areas where eddy currents are utilized include use in energy meters, automobile speedometers, induction alternating current (AC) motors, free-fall devices, as a way of detecting coins in vending machines, to increase temperatures uniformly in induction furnaces, and in proximity/displacement ...

What is eddy current and its application?

Eddy currents are sometimes so strong, that metallic plate become red hot. Application:- (1)-In induction furnace, the metal to be heated is placed in rapidly varying magnetic field produced by high frequency alternating current. Strong eddy currents are set up in the metal produce so much heat that the metal melts.

What is the principle of eddy current?

An eddy current is also called the Foucault current. Eddy currents are swirls of electric currents induced within conductors by a changing magnetic field within the conductor (self-inductance). Eddy current works on the principle of Faraday's law of induction. The Eddy Current Principle works as the Self-inductance.

How eddy current is formed?

When a conductor travels through a magnetic field or when the magnetic field around a stationary conductor changes, eddy currents are produced. Eddy currents can thus be generated anytime the intensity or direction of a magnetic field changes in a conductor.

Testing with eddy current - explained simply

What are eddy currents in one sentence?

Eddy currents are localized electric currents set up in metal parts not normally meant to carry currents, due to changes in electromagnetic fields. Low-frequency inductors are constructed like transformers, with cores of electrical steel laminated to prevent eddy currents.

What are the advantages of eddy currents?

Are eddy currents AC or DC?

Thus eddy currents are a cause of energy loss in alternating current (AC) inductors, transformers, electric motors and generators, and other AC machinery, requiring special construction such as laminated magnetic cores or ferrite cores to minimize them.

What is eddy current in transformer?

Eddy Currents

In a transformer, the magnetic flux created by the primary coil induces a current in the core. This occurs in order to oppose the charge that produced the magnetic flux (Lenz's Law). The currents flowing in the core are called eddy currents.

What is frequency in eddy current?

The supply frequency usually used for the eddy current heating ranges from 10 kHz to 40 kHz.

Why are eddy currents circular?

Eddy currents are always circular in nature because of the reason that current always prefers to take least resistive path. As it is known that for same area of circle and any other finite sided polygon, circle has the least perimeter.

What is eddy current losses?

If an eddy current of magnitude I flows through a core path of resistance r, it will dissipate energy in the form of heat according to the power equation power = I2R. Since this represents energy being expended for no useful purpose, it is considered as an eddy current loss, sometimes called iron loss.

What is the advantages and disadvantages of eddy current?

Eddy current converts the kinetic energy into heat and this is applied in many useful applications like Magnetic Braking in trains, Electromagnetic damping, Induction furnace etc.In this process, there is a loss occur in this system to reduce this we need to increase the core resistance and there is more losses in eddy ...

What is eddy current and its disadvantages?

Disadvantages of Eddy Currents:

There is a major heat loss during cycling eddy currents due to friction in the magnetic circuit, especially where the core is saturated. Thus there is the loss of useful electrical energy in the form of heat. There is magnetic flux leakage.

Why do eddy currents produce heat?

In the area where the eddy currents are flowing, the phenomenon of resistance then generates heat. Increasing the strength of the magnetic field increases the heating effect.

What are the effects produced by eddy current?

The magnetic interaction between the applied field and the eddy currents acts to slow the wheels down. The faster the wheels spin, the stronger is the effect, meaning that as the train slows the braking force is reduces, producing a smooth stopping motion.

How can we reduce eddy current?

Eddy current magnitude can be reduced by designing the core as a set of thin sheets or laminations, in parallel to the magnetic field. Each sheet must be insulated from its neighbours with a thin coating of varnish or oxide film. By laminating the core, the area of each section and hence the induced EMF is reduced.

Are eddy currents useful or harmful?

Solution : They are both, useful and harmful.

What are the three main causes of currents?

How does resistance affect eddy currents?

The resistance felt by the eddy currents in a conductor causes Joule heating and the amount of heat generated is proportional to the current squared. However, for applications like motors, generators and transformers, this heat is considered wasted energy and as such, eddy currents need to be minimized.

How can eddy current be increased?

Stronger magnetic field, thicker material and low resistivity material will increase the size and effect of eddy current whereas thinner material will reduce the effect of eddy currents.

What is edge effect in eddy current testing?

Edge effect is a phenomenon that occurs when an inspection coil is at the end of the test piece. In these instances, eddy current flow is distorted as currents cannot flow at the edge. So, in order to avoid the confusion with flaws, inspection is limited near edges.

What is eddy current and hysteresis loss?

In electric machines, a varying magnetic field causes eddy currents in all metallic parts and hysteresis in ferromagnetic core. The losses caused due to eddy currents are known as eddy current loss and that caused due to hysteresis is known as hysteresis loss.