Distance Protection and Distance Realy.pptx

Switch gear protection

1. CONTENTS 01 02 03 04 05 06 Introduction Distance protection Distance Relay Distance relay in double circuit line Distance relay characteristics Advantages , Dis advantages and applications

2. Introduction Distance Protection : - Distance Protection is non –unit type protection . which measures the Impedance between the Relay Location and the point where the fault is incident and compares it with the Set Value. 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.

3. Distance Protection Distance protection is widely used for protection of transmission and distribution line . It’s having a high speed protection.

4. Distance Relay The distance relay is a distance protection element designed to measure the faulty point. Distance relay principle is based on the determination of the fault impedance from the measured short circuit voltage and current at the relay location. These are double actuating quantity relays with one coil energized by voltage and other coil energized by current. The torque produced is such that when V/I reduces below a set value the relay will operate. During the fault on transmission line the fault current increases and voltage at the fault point reduces.

5. Distance Relay in double circuit line

6. Distance Relay Types According to the dependency of distance relay on voltage and current it’s classified into three types. i.e. 1. Impedance Relay 2. Reactance Relay 3. Admittance or MHO Relay Also 1. Definite distance relay :- It works when the value of reactance or admittance is below a predetermined impedance value of the relay. 2. Time distance relay :- It’s working depends on the value of impedance i.e. on the distance between the fault and the relay point.

7. Impedance Relay Characteristics

8. Reactance Relay Characteristics

9. Mho Relay Characteristics

10. Advantages Dis advantages Application It replaces the protection of overcurrent transmission lines. Available with permanent settings and there is no need to readjust the settings. As it operates on both sides faults of a line, then it is said to be non-directional. The measurement capacity of fault resistance is limited These are most widely used to protect transmission lines and distribution lines over high AC voltages.

11. Conclusion Overall, Distance protection system and distance relay both are needed for protection of transmission and distribution line as primary or backup protection.

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