Overvoltage

Insulation Coordination of Substation

Insulation Coordination of Substation: For steep fronted lightning waves at Insulation Coordination of Substation and at different points on lines, the voltages at sub-stations may exceed the protective level depending on the distances involved and the arrester locations. Hence, it is necessary to decide the number of locations for arresters to optimize the overall cost. …

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Selection of Surge Arresters

Selection of Surge Arresters: These are non-linear resistors in series with spark gaps which act as fast switches. A Selection of Surge Arresters or lightning arrester is shown in Fig. 8.24 and its characteristics are given in Fig. 8.25. A number of non-linear resistor elements made of silicon carbide are stacked one over the other …

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Transmission Line Overvoltage Protection

Transmission Line Overvoltage Protection: Transmission Line Overvoltage Protection against natural or lightning overvoltages and minimizing the lightning overvoltages are done by suitable line designs, providing guard and ground wires, and using surge diverters. Switching surges and power frequency overvoltages are accounted for by providing greater insulation levels and with proper insulation co-ordination. Protection against Lightning …

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Control of Switching Overvoltage

Control of Switching Overvoltage: The Control of Switching Overvoltage and power frequency may be controlled by energization of transmission lines in one or more steps by inserting resistances and withdrawing them afterwards, Phase controlled closing of circuit breakers, Drainage trapped charges before reclosing, Use of shunt reactors, and Limiting switching surges by suitable surge diverters. …

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Switching Surges in Transmission Line

Switching Surges in Transmission Line: Till the time when the transmission voltages were about 220 kV and below, over-voltages due to lightning were of very high order and overvoltages generated inside the system were not of much consequence. In later years, with increase in transmission voltages (400 kV and above), the overvoltages generated inside the …

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Rectangular Travelling Wave

Rectangular Travelling Wave: Reflection and transmission of a Rectangular Travelling Wave at junction points of unequal impedances in a transmission line are of great importance in transmission systems. Depending on the type of impedance at transition points, the Rectangular Travelling Wave is modified, and sometimes a voltage rise or build-up of voltage can occur. The …

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Distortion of Travelling Waves

Attenuation and ┬áDistortion of Travelling Waves: As a Travelling Waves moves along a line, it suffers both attenuation and distortion. The decrease in the magnitude of the wave as it propagates along the line is called attenuation. The elongation or change of wave shape that occurs is called distortion. Sometimes, the steepness of the wave …

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