Engineering Earth

Instrument Transformer (CT and PT) (What is   instrument Transformer? Explain it. Or explain about current transformer and potential transformer. Or explain construction details and working of CTs & PTs ) Current, voltage, power and impedance are the fundamental parameters of a power system. Condition of power system whether it is healthy or not will be determined by variation of these parameters from the values of those at normal operating condition. So the detection of fault and hence clearance of fault can be achieved if we can monitor these quantity throughout the operation. Normally power system variables are of very large magnitude in the range of Kilo Volts and Kilo Amps. It is very much costly and even impossible to use that quantity directly for control and protection but what we can do is that to reduce in proportionate amount and use that reduced quantity in required purpose. Transformer of special design used for that purpose are called instrument transformer. They ...

Semiconductor Materials   Definition: A material that is neither a good conductor of electricity nor a good insulator, but has properties of electrical conductivity somewhere between the two. Semiconductor is a material that is neither a good conductor or a good insulator  but that conducts more electricity when heat, light or voltage is added. Semiconductors are employed in the manufacture of various kinds of electronic  devices, including diodes, transistors, and integrated circuits. Such devices have  found wide application because of their compactness, reliability, power efficiency,  and low cost. Elements of semi conductor materials: The elemental semiconductors are those composed of single species of atoms, such as silicon (Si), germanium(Ge) and Tin(Sn) in column IV and selenium (Se) and tellurium (Te) in column VI of the periodic table. There are, however, numerous compound Semiconductors, which are composed of two or more elements.  •Gallium arseni...

Automatic Voltage Regulator •The automatic voltage regulator is used to regulate the voltage.  • It takes the fluctuate voltage and changes them into a constant voltage.  • The fluctuation in the voltage mainly occurs due to the variation in load on the supply system.  • The variation in the voltage damages the equipment of the power system which can be controlled by installing the voltage control equipment at several places likes near the transformers, generator, feeders, etc. • The voltage regulator is provided in more than one point in the power system for controlling the voltage variations. Working Principle of Voltage Regulator • It works on the principle of detection of errors.  • The output voltage of an AC generator obtained through a potential transformer and then it is  rectified, filtered and compared with reference.  • The difference between the actual voltage and the reference voltage is known as the error voltage.  • This error voltage is...

(Define the underground cable.Explain the construction of underground cable and it's properties.) Underground cables: The transmission and distribution of an electrical power can be done with the help of overhead transmission line or by underground cables. In dense populated area like cities, the use of overhead transmission line is not practicable and in such a case we can use underground power cables. The underground cables of course come with other amenities, the advantage include smaller voltage drops and lesser probability of fault occurrence. On the other hand their production and installation cost is higher and used where overhead lines aren't viable due to practical limitations or risk involved.  A typical underground cable consists of a conductor's covered by a number of insulating and protecting layers necessary for its satisfactory operation.  Construction of Underground Cables: Conductor : Usually one, three or more (depending upon the application) conductors ar...

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Diploma in Electrical Engineering  3rd semester old questions   i. Electronic Circuit Theory (ECT) ii. Civil Constructions and Servey iii. Electrical & Electronic Engineering Material (EEEM) iv. Computer Programming (CP) v. Basic Electronics (BE) vi. Principle of Management and Costing (PMC) Diploma in Electrical Engineering  4th semester old questions   i. Electric Machine ii. AutoCAD (CAD: Computer Aided Design) iii. Power Station iv. Electronics Device and Logic Circuits (EDLC) V. Electrical Measurements and Measuring Instruments (EMMI) Vi. Microprocessor and Microcontroller (MPC) Diploma in Electrical Engineering  5th semester old questions     i.Power Electronics ii.Electric Machine II iii.Switchgear and Protection iv. Control System Components  V. Utilization Of Electrical Energy (UEE) vi. Electrical Installation Design Estimation & Costing Diploma In Electrical Engineering 6th Semester old questions i.Power System Operation and...