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Showing posts with the label Electrical Engineering

Tertiary Winding

Tertiary Winding Figure 1(a).shows the circuit diagram for the forward converter with tertiary winding added to the basic configuration. Such converters are used in computers, word processors, televisions, etc. Operation of Tertiary Winding When the transistor Q is turned on, due to the winding polarities, diode Dm is reverse-biased and does not conduct. However, when Q is turned off, Dm is forward-biased and the current flows through the tertiary winding as shown in Fig.1(b).  The residual energy in the transformer core is returned back to the dc source via diode Dm and the tertiary winding. This is how the tertiary winding helps to demagnetize the core and avoids the core saturation.  Due to the dot convention as shown in Fig. 1(a), the primary winding and tertiary winding will never carry current simultaneously. Associated waveforms are shown in Fig. 2. The dark areas on the waveforms of Fig.2 show the magnetizing-demagnetizing current, given as, Tertiary Winding Advantages (i) It n

Semiconductor - Defination, Types

Semiconductor  any of  a category  of solids (such as germanium or silicon) whose electrical conductivity is between that of a conductor  which  of an insulator in being nearly as great as that of a metal at high temperatures and nearly absent at low temperatures A semiconductor is a substance, generally a strong concoction component or aggravate, that can lead power under a few conditions yet not others, making it a decent medium for the control of electrical current. Its conductance changes relying upon the current or voltage connected to a control cathode, or on the power of illumination by infrared (IR), unmistakable light, bright (UV), or X beams.  The particular properties of a semiconductor rely upon the debasements, or dopants, added to it. An N-type semiconductor conveys current for the most part as adversely charged electrons, in a way like the conduction of current in a wire. A P-type semiconductor conveys current dominatingly as electron lacks called gaps. An opening has a

Trapped Charge Effect

Trapped Charge Effect Trapped charges occur on the transmission lines in three-pole out closure operations. The contact-making of three poles of a circuit breaker is non-simultaneous. Consider breakers at the sending end and receiving ends of a line and a transient ground fault, which needs to be cleared by an auto closure operation. The opening of two breakers is nonsimultaneous and the one which opens later must clear two-line phases at no load. These two phrases can, therefore remain charged at the peak of the power frequency voltage, which is still present when the closure takes place. After the dead time, one breaker has to close with two phases still charged. If the closing instant happens to be such that the trapped charge and power frequency voltage are of opposite polarity, maximum transient overvoltage will occur. And these overvoltages will result in the over-current m transmission line.

Suspension Definition and Properties

Suspension Definition and Properties The substance of little size particles that are insoluble in the solvent, but which are visible distinctly through the naked eye is called a suspension . Thus it is a heterogeneous mixture of two or more substances and in it, the sizes of the dispersed particles are of the order of 10-5 cm or more. The little particles can be filtered and these are temporary which have a common tendency to scatter from the medium of dispersion. There are so many examples of suspension in our common walk of life like the water of the river, smoke in atmospheric air, etc. Properties of Suspension The suspension is a heterogeneous mixture. The particles of suspension can be seen by the naked eye and its size is of the order of 10-5 cm or more. The particles of suspension scatter a beam of light passing through it and make its path transparent (visible). The suspension is unstable because the solute particles settle down when it is left undistributed. That'

SF6 Sulfur Hexafluoride Circuit Breaker

SF6 Sulfur Hexafluoride Circuit Breaker SF6 Circuit Breakers Is a Circuit Breaker whose Excellent insulating, arc-extinguishing, and physical and chemical properties of SF6 gas are the greater advantages of SF6 circuit breakers. The gas is noninflammable and chemically stable. SF6 Circuit Breaker Diagram What is SF6 Gas The gas costs less if manufactured on a large scale.  The gas is transported in liquid form in cylinders. Before filling the gas, the circuit breaker is evacuated  40 the pressure of about 4 mm of mercury so as to remove the moisture and air.  The gas can be reclaimed by the gas handling tank. The sulfur hexafluoride possesses very good insulating properties and outstanding arc-quenching Thametcristics which make it an ideal medium for circuit inscription. The physical, chemical, and dielectric properties and are-quenching characteristics of SF6 gas are given below: It is colorless, odorless, non-toxic, and noninflammable gas. This gas is extremely stable an

Berry Type Transformer

Berry Type Transformer Berry type transformer is like Shell type transformer, just they have a conveyed attractive circuit. This center development is like the spokes of a wheel. The quantity of the attractive transition way is more than 2.   It is commonly kept in firmly fitted sheet metal tanks. The tanks are built of explicit top-notch steel plate cut shaped and welded into the unbending structures. Every one of the joints is painted with an answer of light blue chalk which turns dull within the sight of oil, revealing even the minutest breaks. The tanks are loaded up with the unique protecting oil. The whole transformer gets together is submerged in the oil. The oil served two capacities. keep the loops cool by flow Gives the transformers an extra protection

Electrical Questions And Answers Free

Electrical Questions And Answers Free Electrical interview questions for electrical alumni. Much of the time asked interview inquiries with answers under the subjects like electrical machines, Transmission and distribution, Power hardware and some broad essential questions. Why do not we employ RC or transformer coupling for extremely low frequencies (< 10 Hz) Ans. It is because, at such low frequencies (<10 Hz), the electrical and physical sizes of capacitors and transformers become too large. Why should coupling capacitors in transistor amplifiers possess high values Ans. A transistor amplifier (CE arrangement) has a low input impedance of the order of 500 Q or so. It is desired that reactance offered by the coupling capacitor should not be more than 20 9. To achieve this, large values of coupling capacitances must be used. Generally, the capacitance of coupling capacitors ranges from 1 ”F to 10 “F.  In a two-stage RC coupled amplifier; why are the capacitors required for the s

Why RC coupling very popular

Why RC coupling very popular The RC coupling is very popular due to two basic reasons : (I) It employs inexpensive resistors and capacitors. (2) It provides constant voltage gain over the audio-frequency range. RC Coupled A Resistance Capacitance (RC) Coupled Amplifier is essentially a multi-organize enhancer circuit widely utilized in electronic circuits. Here the individual phases of the enhancer are associated together utilizing a resistor-capacitor mix because of which it bears its name as RC Coupled. Focal points of RC Coupled Amplifier Shabby, prudent, and minimized as it utilizes just resistors and capacitors. Offers a consistent addition over a wide recurrence band. Hindrances of RC Coupled Amplifier Unsatisfactory for low-recurrence intensification. Low voltage and power gain as the compelling burden opposition (and thus the increase) is diminished because of the way that the contribution of each stage exhibits low protection from its next stage. Dampness delicate, ma

Mode Locking

Mode Locking Mode Locking Lasers can be made to operate continuously or in pulses. As an example, the bandwidth of the 632.8 nm line in the He-Ne laser is 1.5 GHz, so that the shortest pulses that a He-Ne can produce would be 0.67. ns long. This is not particularly short by modem standards. Dye lasers typically have gain bandwidths greater than 10*1000000000000 Hz and can be used to generate pulses shorter than 100 fs. This is achieved by a technique called mode-locking. To achieve shorter laser pulses, mode locking of the laser modes is done Types of Mode Locking In a comparison of ultrafast and normal lasers, an ultrafast laser simultaneously lases in many different modes (the more the better), but the phases of the different modes are completely uncorrected. This will manufacture random (unpredictable) Fluctuations within the intensity over time. Mode locking describes the set of techniques that are used to generate a known correlation between the phases and therefore create it pos