Where is Mho relay used?
These relays are used in long transmission, medium, and short transmission lines. The working principle of Mho relay is, it used for long-distance transmission lines because these lines generally experience power swinging transients as well as load shedding problems.
What is a Mho relay?
Mho relay is a voltage restrained directional relay. Important Points: Reactance relay is suitable for the protection of a short transmission line because its operation is independent of arc resistance. The relay which is selected for a long transmission line should be less affected due to power swings.
Which relay is used for Mho relay?
Reactance relay is suitable for the protection of the short transmission line because its operation is independent of arc resistance. Impedance relay is suitable for medium transmission lines.
What is the difference between 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.
Why Mho relay is inherently directional?
A Mho relay measures a component of admittance |Y| ∠θ. But its characteristic when plotted on the impedance diagram (i.e., R-X diagram) is a circle passing thro’ the origin shown in the fig. It is inherently a directional relay as it detects the fault only in the forward direction.
What is distance relay?
A distance relay is a type of protection relay most often used for transmission line protection. Distance relays measure the impedance from the installation side to the fault location and operates in response to changes in the ratio of measured current and voltage.
Why is it called a MHO relay?
It is inherently a directional relay as it detects the fault only in the forward direction. The relay is called Mho relay because its characteristic is a straight line, when plotted on an admittance diagram (G-B axes i.e., conductance – susceptance axes) as in the figure.
What are the different types of distance relay?
There are two types of distance relays in use for the protection of power supply, namely ;
- Definite-Distance relay which operates instantaneously for fault up to a pre-determined distance from the relay.
- Time-Distance relay in which the time of operation is proportional to the distance of fault from the relay point.
Why MHO relay is inherently directional?
Why mho relay is called mho relay?
What are distance relays?
Which relay is used for feeder?
Translay relay
Translay relay: The translay relay is a differential relay. The arrangement is similar to overcurrent relay, but the secondary winding is not closed on itself. These types of relays are used in the feeder protection and the scheme is called the Translay scheme.
How is the admittance of a MHO relay measured?
A Mho relay measures a component of admittance |Y| ∠θ. But its characteristic when plotted on the impedance diagram (i.e., R-X diagram) is a circle passing thro’ the origin shown in the fig. It is inherently a directional relay as it detects the fault only in the forward direction.
Can a MHO relay trip under power swing?
Comparison of Mho characteristic and Impedance Characteristic under power swing conditions AB is the line to be protected. Impedance characteristic relay will trip even for the fault points behind location A which is nothing but a ‘nuisance tripping’.
What is the operating characteristic of a relay?
The relay operates when the impedance seen by the relay within the circle. The operating characteristic showed that circle passes through the origin, which makes the relay naturally directional.
What kind of relay is an induction Cup?
It is an electromagnetic induction cup type mho relay. The upper and lower poles are energized by a voltage V to produce a polarizing flux. The capacitor connected in series provides memory action. The left is energized by a current is the operating quantity.