What is the difference between the impedance relay and mho relay?

impedance is non-directional and used in medium transmission lines. mho relay is directional and used in long transmission lines.

What is the difference between impedance and mho characteristic?

The mho relay is reliable because it combines both the directional and distance measuring functions in one unit. The impedance type relay is suitable for phase fault relaying for lines of moderate length. The arc affects the impedance relay more than the reactance relay but less than the mho relay.

What is an impedance relay?

An impedance relay is a voltage restrained overcurrent relay. The relay measures impedance up to the point of fault and gives tripping command if this impedance is less than the relay setting Z.

Why mho type relay is affected by arc resistance more than other types of distance relays?

Because the mho relay is affected by arc resistance more than any other type, it is applied to longer lines. The fact that it combines both the directional and the distance- measuring functions in one unit with one contact makes it very reliable.

What is the advantage of static distance relay over electromechanical distance relay?

Advantages of static relay over electromechanical relays: As there are no rotating parts involved in the construction of static relays, these relays will give a faster response than electromagnetic relays. And also there are no frictional losses the power required for the static relays is less.

Which relay is most affected by arc resistance?

the Mho relay
The operation of the Mho relay is most affected due to arc resistance.

Why impedance so a distance relay is also known as impedance relay?

In normal operating condition, restoring torque is more than deflecting torque. Hence relay will not operate. But in faulty condition, the current becomes quite large whereas voltage becomes less. As the ratio of voltage to current is nothing but impedance so a distance relay is also known as impedance relay.

What is the difference between semi static and fully static relay?

The term previously applied to this type of relay was semistatic relay. Static relay without output contacts – A static relay having no contact in its output circuit(s). The term previously applied to this type of relay was fully static relay.