What is directional and non directional over current?

Directional really is connected towards load side of the line which will trip if overcurrent flows from load towards the source and non directional relay is connected at the source side which will trip if fault occurs irrespective of the direction of current.

What is non directional over current relay?

Non-directional Induction Overcurrent Relay Construction: This relay is also called earth leakage induction type relay. The overcurrent relay operates when the current in the circuit exceeds a certain preset value.

What is meant by directional features of a directional overcurrent relay?

Operating Principle of Directional Over Current Relay: Conventionally denotes that forward direction refers to power flow away from the busbar (towards the protected zone), while reverse direction refers to power flowing towards the busbar.

What does a directional power relay do?

The directional relay means the relay operates for the specific direction of the actuating quantity in the circuit. The directional power relay operates when power in the circuit flows in the specific direction.

What are the types of directional relay?

Directional-overcurrent relays are combinations of directional and overcurrent relay units in the same enclosing case. Any combination of directional relay, inverse-time overcurrent relay, and instantaneous overcurrent relay is available for phase- or ground-fault protection.

What is a 67 relay?

Abstract: Directional overcurrent relaying (67) refers to relaying that can use the phase relationship of voltage and current to determine direction to a fault. There are a variety of concepts by which this task is done.

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

The directional relay will respond to any type of current, real or reactive. The reverse power relay, normally used in generator protection, responds to current drawn by a motor or generator (or resistor) that is producing work, as opposed to current that supports a magnetic field.

What is reverse power or directional relay?

Reverse Power Relay is a directional protective relay that prevents/protect the generator from motoring effect (going to reverse direction). It is used where generator runs in parallel with other utility or generator.

What is induction Cup relay?

Induction Cup Relay. The relay which works on the principle of electromagnetic induction is known as the induction cup relay. The relay has two or more electromagnet which is energized by the relay coil. The static iron core is placed between the electromagnet as shown in the figure below.

What is biased differential relay?

The biased-differential relay is a low-impedance relay and compares with the high-impedance relay as follows: Advantages of biased scheme: Can operate with CTs with a lower knee point and less accuracy, since the relay is of a low-impedance type. The bias feature compensates for any CT.

What is directiondirectional over current relay?

Directional over current relays operate in either forward or reverse directions with over current protection. If the directional relay set in Forward direction means if a fault occurs in forward zone then only relay operates. Conversely, if the relay set in Reverse direction means if a fault occurs in reverse zone then only relay operates.

Where does the fault current flow in a relay?

The fault current flows into the non-polarity mark of the CT connected to Circuit Breaker 4, so the Directional Overcurrent (67) relay sees the fault in the reverse direction. The orange/red shaded region indicates the typical region for a fault behind a relay.

What does the Directional Overcurrent relay connect to circuit breaker 4 see?

Let’s look at what the Directional Overcurrent (67) relay connected to Circuit Breaker 4 sees under the same conditions. This relay is designed to protect the same transmission line from the other direction.

How do you determine forward and reverse current in a relay?

Forward and reverse are typically determined by the normal flow of current into the relay, so be sure to confirm the CT connections before you make any assumptions. Incorrectly determining forward and reverse is an easy mistake to make.