Category: 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. […]

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 […]

Insulation Coordination in High Voltage

Insulation Coordination in High Voltage: Insulation Coordination in High Voltage – Electric power supply should ensure reliability and continuity to the utility concerns. Hence, the power lines and sub-stations are to be operated and protected against overvoltages such that the number of failures are as few as possible. At the same time, the cost involved […]

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 […]

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. […]

Power Frequency Overvoltages in Power Systems

Power Frequency Overvoltages in Power Systems: The Power Frequency Overvoltages occur in large power systems and they are of much concern in EHV systems, i.e. systems of 400 kV and above. The main causes for power frequency and its harmonic overvoltages are Sudden loss of loads, Disconnection of inductive loads or connection of capacitive loads, […]