Correct option is C
· A Mho relay, also known as an admittance relay, is a type of distance relay that is particularly suitable for the protection of transmission lines in systems with high voltage, including both extra-high voltage (EHV) and ultra-high voltage (UHV).
· Mho relays are favored in these applications because they are inherently directional, which helps in distinguishing between faults that occur in the forward direction from those that occur in the reverse direction.
· These relays are designed to detect faults based on impedance, and their operation is more stable and reliable at higher voltage levels. Therefore, they are well-suited for protecting long transmission lines that operate at EHV and UHV levels.
· Reactance relays are typically used for the protection of short transmission lines.
· Impedance relays are commonly used for the protection of medium to long transmission lines.
