They do. See http://en.wikipedia.org/wiki/Transmission_lineZunairaMaryam said:I want to why TEM waves are not supported by transmission lines? and where is the point of difference in using waveguides and transmission lines?
The transposition of transmission lines can significantly impact the accuracy of protection systems. When transmission lines are transposed, their electrical characteristics, such as impedance and capacitance, are altered. This can lead to changes in fault currents and voltage profiles, which can affect the operation of protection systems. In some cases, transposition can result in protection systems not detecting faults or misoperation of protection relays.
The main risk of not considering transmission line transposition in protection system design is the possibility of protection system failure during a fault. If the fault current and voltage profiles are different from what the protection system is designed to detect, it may not operate correctly, leading to prolonged outages or damage to equipment. Additionally, not accounting for transposition can result in increased maintenance and testing costs for the protection system.
In some cases, transmission line transposition can improve the performance of protection systems. By altering the line's electrical characteristics, transposition can reduce the fault current and voltage levels, making it easier for the protection system to detect and isolate faults. However, this improvement is highly dependent on the specific system and may not always be the case.
Transmission line transposition should be considered during the initial design of protection systems. This involves analyzing the electrical characteristics of the transposed line and adjusting the protection system settings accordingly. In some cases, specialized protection relays may be required to account for transposition. Regular maintenance and testing should also be performed to ensure the protection system is accurately detecting faults.
While transmission line transposition can improve the performance of protection systems, there are also potential drawbacks to consider. Transposition can be costly and time-consuming, requiring specialized equipment and expertise. It can also introduce additional complexity and potential points of failure in the protection system. Therefore, careful consideration and analysis should be done before implementing transposition solely for the purpose of improving protection system performance.