The core of a transformer is subjected to an alternating magnetizing force and for each cycle of emf a hysteresis loop is traced out.
The lagging phenomenon of B behind H is called hysteresis. The tip of hysteresis loop can be joined to obtain the magnetization characteristics.
A hysteresis loop shows the relationship between the induced magnetic flux density B and the magnetizing force H. It is often referred to as the B-H loop. The area of a hysteresis loop varies with the type of material. The area, and thus the energy loss, is much greater for hard materials than for soft materials. A disturbance in the alignment of the domains of a ferromagnetic material causes energy to be expended in taking it through a cycle of magnetization.
This energy appears as heat in the specimen and is called the hysteresis loss. Save Save. According to Lenz,s law this induced emf will oppose the flow of current, therefore, in order to maintain the current I in the coil, the source must supply an equal and opposite emf. Hence applied emf,. Energy consumed in short time dt, during which the flux density has changed,.
The laminations are insulated from each other by a thin coat of varnish. In conclusion, the combined hysteresis and eddy current loss are known as the core losses.
You must be logged in to post a comment. Want create site? Find Free WordPress Themes and plugins. This loss due to resistance of copper winding. Primary copper losses in transformer take place due to the flow of current in the primary winding of transformer. Secondary copper losses take place due to the flow of current in the secondary winding of transformer.
Apart from these major losses we have dielectric loss in transformer. As its name says dielectric losses take place in the insulation coating of the transformer due to the large electric stress.
It is constant and in the case of low rating transformers, it is neglected. The relationship between the magnetizing force, H, and the flux density, B, is shown on a hysteresis curve, or loop. The area of the hysteresis loop shows the energy required to complete a full cycle of magnetizing and de-magnetizing, and the area of the loop represents the energy lost during this process.
This induced EMF causes circulating currents to flow, referred to as eddy currents. The power loss caused by these currents is known as eddy current loss.
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