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State the advantages and disadvantages of alloying steel with silicon for use as magnetic materials in transformer and electric machines.
Extensive utilize, is made of iron-silicon alloy termed as silicon steel for relatively strong alternating magnetic fields usually used in transformers, reactors, electrical rotating machines, relays and electromagnets. Silicon sharply raises the electrical resistivity of iron therefore decreasing the iron losses because of eddy currents. This increases the permeability at low and moderate flux densities but reduces this at high densities. Addition of silicon to iron decreases the hysteresis loss. The magneto striction effect is reduced also. A, steel with more than 5 percent silicon may be too hard and brittle to be simply workable. The introduction of silicon in steel was a significant development. Previously, iron was used as the core material in the form of sheets, the material slowly deteriorated because of repeated cooling and heating. This difficulty is overcome using silicon sheet steel like core material. High silicon sheet steel along with silicon of about 4 percent is used in magnetic circuits of power transformers that operate at flux densities of about 1 Wb/m2. The cores of rotating electrical machines are slotted along with the teeth having small cross sectional areas. The flux density in teeth is higher, of the order of 1Wb/m2. To acquire high flux density in the case of high silicon steel, the magnetising current essential is very large. Also punching slots in high silicon steel would be not easy because this is harder and more brittle.
An induction motor has a starting current that is 6 times the full-load current and a per-unit full- load slip of 0.04. The machine is to be provided with an autotransformer starte
Find the current through each resistor for the networking below using Mesh Analysis and Nodal Analysis.
If a current of 20A flows for five minutes, find the quantity of electricity transferred. Quantity of electricity, Q = It = 20 x 5 x 60 = 6000C
Q. What do you mean by Superposition and linearity? Mathematically a function is said to be linear if it satisfies two properties: homogeneity (proportionality or scaling) and
The winding of an electromagnet has an inductance of 3H and a resistance of 15?. When it is connected to a 120 V d.c. supply, Determine: (a) the steady state value of current f
The devices in power system shown in Figure 2 have the following ratings: G1 : 100 MVA, 13.8 kV grounded Y, X” = 0.15 pu, X2 = 0.015 pu Xo = 0.05 pu G2 : 50 MVA, 20.0 kV grounded
Q. How do you calculate the insulation resistance of transformer and what is the minimum value? Ans. The insulation resistance of the transformer will be calculated by using
Q. Define waves and transmission lines? In basic circuit theory we neglect the effects of the finite time of transit of changes in current and voltage and the finite distances
N-type semiconductor is an example of (A) Extrinsic semiconductor. (B) Intrinsic semiconductor. (C) Super conductor. (D) Insulators.
find the output Y in the circuit
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