A mho relay is used for the protection of:

A mho relay is used for the protection of:

Right Answer is:

Long Transmission Line


MHO relay is a high-speed relay and is also known as an admittance relay. lt is well known that a long line is less stable than a short line; that is, a long line has a larger swing angle δmax compared to a short line. The short line has a higher Pmax than that of a long line.

Why is Mho’s Relay used for Long Transmission Line?

  • Mho relay comes in the category of the distance relay protection scheme.
  • The mho type relay is most suited for long lines because there are more chances of severe synchronizing power surges on the system.
  • MHO Relay is less affected by the power swing.
  • It does not need any additional equipment to prevent tripping during these surges.
  • The mho relay occupies the least space on an R-X diagram for a given line section and is, therefore, least affected by abnormal system conditions except for the line faults.
  • Since the mho relay is most affected by arc resistance, it is used for long lines.
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