Lightning or surge arresters serve the same purpose on an electric circuit or line as a safety valve on a boiler. A safety valve on a boiler relieves a high pressure by allowing steam to blow off until the high pressure is reduced to normal, at which time the safety valve closes again and is …
Most insulations fail during one of the following events: Switching overvoltage due to the inductive and capacitive energy of the system overshooting the system voltage that can be as high as 2 × rated voltage. This is analogous to overpressure due to water hammer when a water pipe is suddenly shut off (switched-off). Lightning overvoltage …
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The relay operation is a function of the input quantities, such as current, voltage, impedance, and/or phase angle. The relay can be made to respond to either a single quantity or a combination of two or all input quantities. When the relay is operated by a single quantity, its response is strictly a function of …
A perfect cable can be electrically modeled by a single capacitor. The longer the cable, the larger the capacitance of this capacitor. As the insulation of the cable degrades, losses in this capacitor increase which can be measured by tan delta testing of the cable. The measurements can be compared with previous test measurements and …
Cable testing is conducted to chart the gradual deterioration over the years, to do acceptance testing after installation, for verification of splices and joints, and for special repair testing. It is always appropriate to conduct the cable insulation resistance measurement test first, and if the data obtained looks good, then proceed with the DC overpotential …
In this article, I shall be discussing the existing underground cable fault location methods. Faults in a cable may vary widely, and similar faults may show different symptoms depending upon the cable type, operating voltage, soil condition, and so on. Faults can be considered to be shorts, opens, or nonlinear. A short is defined as …
A current limiting reactor is a coil which has a large inductive reactance in comparison with its ohmic resistance. It consists of a few turns of heavy copper strip, sometimes cast directly in concrete so that it can withstand large stress developed by the fault currents. Generally, the reactance of the power system under fault …
Hi friends, In this article, I am going to discuss components of HVDC system, working, types, advantages and disadvantages of the HVDC transmission system. I hope you will find it useful and exciting. Transmission and distribution of electric power are done using alternating current, mainly due to economic reasons. However, due to the development of …
As per present terminology, voltages less than 300 kV are termed as High Voltages. The voltages in the range of 300 kV to 765 kV are known as Extra High Voltages (EHV). The voltages which are 765 kV are termed as Ultra High Voltage (UHV). In India, transmission voltage ranges from 66 kV to 400 …
Classification of cables can be done in two ways according to Classification of Cables According to Voltage However, the classification of cables on the basis of voltage is more common, according to which they can be divided into the following categories: Also, electrical cable classification can be done on the basis of their construction as …
