Directional relay pdf

What is a directional relay?
What are the inputs to directional relay?
What is the principle of directional overcurrent relay?
What are the disadvantages of directional relays?
What do directional relays responds to?
What are the three types of relays?
What is the basic principle of relay?
What is the difference between reverse power relay and directional relay?
What are the 4 parts of a relay?
What is MTA in directional relay?
What are the 4 pins on a relay?
Why do we use directional overcurrent relay?
What are the advantages of directional overcurrent relay?
Which distance relay is directional relay?
What is the advantage of directional protection?
What is the device function number of a directional relay?
Is reactance relay a directional relay?
What is the difference between reverse power relay and directional relay?
What is difference between directional and non directional OC relay?
Why do we use directional overcurrent relay?
Which distance relay is directional relay?
Is earth fault relay directional or non-directional?
Why is MHO relay directional?
Is reactance relay a directional relay?
What is the most commonly used relay?
What is T1 and T2 in relay?
What are the 2 parts of a relay?

What is a directional relay?

Definition: A protection relay in which the tripping decision is dependent in part upon the direction in which the measured quantity is flowing.

What are the inputs to directional relay?

Abstract: Conventionally, for power protective relay applications, overcurrent relaying is made directional by use of two inputs, the operating current and a reference or polarizing quantity (either voltage or current) that does not change with fault location.

What is the principle of directional overcurrent relay?

Directional overcurrent relays respond to excessive current flow in a particular direction in the power system. The relay typically consists of two elements. One is a directional element, which determines the direction of current flow with respect to a voltage reference.

What are the disadvantages of directional relays?

Disadvantages or demerits:

The directional feature is absent in electromagnetic relays. Requires periodic maintenance and testing unlike static relays. Relay operation can be affected due to ageing of the components and dust, pollution resulting in spurious trips.

What do directional relays responds to?

What are the three types of relays?

The three main types of relays are electromechanical, solid-state, and reed.

What is the basic principle of relay?

It works on the principle of electromagnetism. The electromagnetic field that creates the temporary magnetic field is energised when the relay's circuit detects the fault current. This magnetic field moves the relay armature to open or close connections.

What is the difference between reverse power relay and directional relay?

P RINCIPLE OF R EVERSE POWER R ELAY A reverse power relay is a directional relay that is used to monitor the power flow from generator (running in parallel with another generator or the utility) and in case of abnormal condition take appropriate action.

What are the 4 parts of a relay?

A simple electromagnetic relay consists of a coil of wire wrapped around a soft iron core (a solenoid), an iron yoke which provides a low reluctance path for magnetic flux, a movable iron armature, and one or more sets of contacts (there are two contacts in the relay pictured).

What is MTA in directional relay?

MTA is the maximum torque angle setting. Page 4. 3. Microprocessor-based relays also offer the user the choice of independently applying a negative-sequence voltage, zero- sequence voltage, zero-sequence current, or dual zero- sequence, polarized directional element—all in one product.

What are the 4 pins on a relay?

4 Pin Relay

4 pin relays use 2 pins (85 & 86) to control the coil and 2 pins (30 & 87) which switch power on a single circuit. There are 2 types of 4 pin relay available; normally open or normally closed. A normally open relay will switch power ON for a circuit when the coil is activated.

Why do we use directional overcurrent relay?

Directional overcurrent relay is used for the protection of ring main distribution lines. When there exists a sub-transmission network or a complex distribution, the relays is used to improve the coordination of the system.

What are the advantages of directional overcurrent relay?

Due to its ability to detect the direction of a short-circuit current, directional overcurrent protection helps to protect an installation against short-circuit currents that could circulate in both directions through the circuit breaker.

Which distance relay is directional relay?

The relay is called Mho relay because its characteristic is a straight line, when plotted on an admittance diagram. It is inherently a directional relay as it detects the fault only in the forward direction.

What is the advantage of directional protection?

Directional protection enables better discrimination of the faulty part of the network than with overcurrent protection.

What is the device function number of a directional relay?

91 Voltage directional relay A relay that operates when the voltage across an open circuit breaker or contactor exceeds a given value in a given direction.

Is reactance relay a directional relay?

Reactance relay is an overcurrent relay with directional limitation. The directional element is arranged to develop maximum negative torque when its current lag behinds its voltage by 90°. The induction cup or double induction loop structures are best suited for actuating reactance type distance relays.

What is the difference between reverse power relay and directional relay?

What is difference between directional and non directional OC relay?

Directional relays are designed to locate or sense the fault in a particular direction only, it will not sense fault if fault occurs in opposite direction. While non directional relays don't have directional features & will sense the fault in both directions.

Why do we use directional overcurrent relay?

Which distance relay is directional relay?

Is earth fault relay directional or non-directional?

It is a directional relay. Earth fault relay responds to fault in which power flow is in the set direction from the CT and PT locations. Thus, directional relays are used when power can flow from both directions to the fault point.

Why is MHO relay directional?

This is because if we use directional relay with the Reactance Relay then Reactance Relay will operate even under normal loading condition if the system is operating at or nearer to unity power factor. The Relay used to give the directional feature in the Reactance relay is called MHO Relay.

Is reactance relay a directional relay?

What is the most commonly used relay?

Electromechanical Relays. Electromechanical relays are perhaps the most widely used relays in ATE applications today. They are made of a coil, an armature mechanism, and electrical contacts.

What is T1 and T2 in relay?

Terminals T1 and T2 are a thermally activated contact on the resistor to indicate an overheat condition of the resistor. The contacts are normally closed and open once the braking resistor temperature reaches 120 degrees Centigrade. The minimum voltage/current for these contacts is 24VDC at .

What are the 2 parts of a relay?

Main Parts of a Relay

The primary side and the secondary side. The Primary Circuit provides the control signal to operate the relay. This could be controlled by a manual switch, a thermostat or some type of sensor. The primary circuit is generally connected to a low voltage DC supply.