If the core is solid and made up from ferromagnetic materials, it effectively acts as a single short-circuited turn. 4. Similarly, when it comes to electricity, eddies are the circular movement of currents. Hence, high grade or silica steel can be used for designing the core within a transformer because it has extremely less area of the hysteresis loop. Damping: The coil of the measuring instrument is mounted in the light metal frame. However, a common definition of Core Loss is the amount of power that is lost when an electric current flows through a transformer. Heat loss due to eddy current can be reduced by the lamination of the iron core. Eddy current loss depends upon the rate of change of flux as well as the resistance of the path, it is reasonable to expect this loss to vary as the square of both the maximum flux density and frequency. However, the eddy current can be usefully used in the following applications. Eddy current loss in the transformer is . 1.Primary copper losses in transformer take place due to the flow of current in the primary winding of transformer. Eddy currents are reduced by using multiple plates instead of using a large plate. V Watts Where; K - coefficient of eddy current. In order to reduce the eddy current losses in the transformer the core is formed by stacking thin plates called laminations together and each plate is insulated or varnished so that the flow of eddy current is confined to a very small cross section area of each plate and insulated from other plates. Let us now calculate the resistance offered by the lamination to the eddy current. Total copper losses=IR= (I1)R1+ (I2)R2 Question is When are eddy-current losses in a transformer reduced?, Options are (A) If laminations are thick., (B) If the number of turns in primary winding is reduced., (C) If the number of turns in secondary winding is reduced., (D) Iflaminations are thin., (E) , Leave your comments or Download question paper. Eddy currents are circulating currents present in the magnetic core of the transformer. This will decrease the eddy current and hence the losses made by it too. EXPLANATION: The eddy current loss can be reduced by increasing the resistance of the core. Queries Solved:1. Applications of Eddy Current The eddy current is undesired in the motor, transformer as it cause heat loss which is wastage of energy. Numerical Example 2 In designing an "energy efficient" motor, there are obviously several options. The current that is lost in the form of heat dissipation in the conductor of windings is known as copper loss. They may produce undesirable effects if the large eddy current is allowed into the core of a choke coil, transformer, etc. The eddy current loss is proportional to; Eddy Current loss (We) = K x I2 R (Where K is the eddy current constant) From above it is clear that the higher the current, the higher is the loss. Continue Reading Matt Jennings Former Youth Basketball Coach Updated Aug 31 Promoted f2. Application of eddy currents: According to Ohm's Law, the lower resistance causes a higher current . Copper loss. By making use of a laminated core, the eddy currents produced in the core of a transformer are reduced. Eddy current loss in the transformer is given by: Pe = Ke Bm2. These currents occur due to the difference in magnetic flux in the core of the transformer. = AE2/64k. Eddy current losses in transformer In this video we explain what is eddy current losses in transformer How to reduce eddy currentHow eddy current makes in tr. 2. The solid core has a larger cross-section area, therefore it has lower resistance. It is a nuisance in a transformer. As these losses are eddy-current losses, they can be reduced by careful material selection and thoughtful design. Hysteresis loss in transformer is denoted as, Eddy current loss in transformer is denoted as, Where, K h = Hysteresis constant. Its value depends upon the nature of magnetic material B m - Maximum value of flux density in Wb/m 2 t - Thickness of lamination in meters f - Frequency of reversal of the magnetic field in Hz V - Volume of magnetic material in m 3 The eddy's current are a cause of energy loss in alternating current (AC) inductors, transformers, electric motors and generators and other AC appliances or machinery they are reduced by laminating the magnetic cores. To reduce the eddy current loss, the first way is by laminating the core -- that's why you usually see transformers having many layers or stripes on the sides. By doing so, eddy voltages can be reduced and the resistance to eddy currents can be increased which will finally result in lower core losses in the machines. Suggest Corrections 2 Similar questions The eddy current loss can be reduced as follows By using thin sheets, called laminations which are insulated from each other by a thin coating of varnish, instead of using a solid block of magnetic material. Especially in a transformer core, if the core is solid metal (usually iron), the eddy currents are expansive, in counter to the coil current. t2. K e = Eddy current constant. To do that, the core is formed by combining several insulated or laminated metal plates. Rlamination= Resistance offered by each lamination = 4k/A. Hysteresis losses can be reduced by using material that has less area of the hysteresis loop. How can hysteresis loss be reduced in transformer? 2.Secondary copper losses take place due to the flow of current in the secondary winding of transformer. Eddy currents can be reduced by channelizing the current paths in a conductor. These circulating currents are called Eddy Currents. silicon steel). Methods to reduce the energy loss in transformer: Use of low resistance wire for the winding of the coil. Created by Mahesh Shenoy. K f = form constant. . Eddy current is not used in a transformer. 2. For example, a small transformer may suffer a smaller Core Loss than a large transformer. The magnitude of the eddy currents produces a large current since the resistance of the metallic conductor becomes low. Eddy is a circular movement of water in a pond. . They can be minimized by adding slots in the conductor surface & laminating. Eddy currents are current loops formed over conductor surfaces due to changing magnetic flux. Types of Transformer Loss. The heat generated can be kept to a minimum by using a magnetic material which has a low hysteresis loss . This loss is called eddy current loss. The Hysteresis Loss and Eddy Current Loss in fact can be shown to depend upon the square of lamination thickness. Eddy current losses can be reduced by making the core of a stack of plates electrically insulated from each other, rather than a solid block; all transformers operating at low frequencies use laminated or similar cores. Therefore, Eddy Current Loss in each Lamination = (emf induced)2 / Rlamination. We try to limit eddy currents by limiting the physical distance they travel by making transformer cores (and motor rotors) from a stack of laminated plates, rather than one solid chunk. Copper loss can simply be denoted as, I L2 R 2 + Stray loss Where, I L = I 2 = load of transformer, and R 2 is the resistance of transformer referred to secondary. Due to heating of the conductor there is a loss in energy. While energy saving is always desirable, there are cases where other considerations require a compromise. They are useful in induction heating, levitating, electromagnetic damping, and electromagnetic braking. They will occur when the conductor experiences a changing magnetic field. As these currents are not responsible for doing any useful work, and it produces a loss (I 2 R loss) in the magnetic material known as an Eddy Current Loss. Because the resistance of the bulk conductor is usually low, eddy currents often have large magnitudes and heat the conductor. So option 1 is not correct. Eddy Current Loss in Transformer. The lamination thickness usually varies from 0.3 to 5 mm for electromagnetic devices used in power systems and from about 0.01 to 0.5 mm for devices used in electronic applications where low Core Loss in transformer is desired. As there are 4 laminations, hence total eddy current loss. One easy solution for how to reduce eddy current losses in the transformer is to make the core by stacking thin sheets together. This loss can vary depending on the transformer's construction, size, and specific application. Interview Question on transformer Loss.3. How to reduce hysterisis loss. Hence . Solution The correct option is B By using laminated plates as the core of the transformer. How to reduce Eddy current Loss. Eddy current losses due to joule heating in the core that are proportional to the square of the transformer's applied voltage. . How can we minimize the core losses in a transformer? Hence the eddy current loss can be reduced in transformers, electric motors and alternators by using thin electrically insulated plates stacked together to form a core instead of solid ones. Using a magnetic material of high resistivity (e.g. = A (E/4)2 / 4k.
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