Directional Over Current Relay Working Principle Pdf A directional overcurrent relay operates on the same principle as that of an overcurrent relay. but in an overcurrent relay, the driving torque is developed due to the magnetic fields produced by the operating current of the circuit given through a current transformer. Directional element: it is essentially a directional power relay which operates when power flows in a specific direction. the potential coil of this element is connected through a potential transformer (p.t.) to the system voltage.
Directional Over Current Relay Working Principle Pdf Directional overcurrent relays combine overcurrent protection with phase displacement measurement between the current and polarizing voltage, tripping only when the current exceeds a threshold and the phase displacement is within 90 degrees of the characteristic angle. For directional over current relay, the fault current can flow in both the directions through the relay either forward or reverse, depending upon fault location. therefore, it is necessary to make the relay respond for a particular defined direction, so that proper discrimination is possible. Relays with this principle are called directional relays. for example, overcurrent relays can be made directional by adding above discrimination logic to well known overcurrent logic. such relays are called as directional overcurrent relays. In this technical guide we will walk you through everything you need to know about directional and non directional relays, their working principles, applications, and how they function within substation protection schemes.
Directional Over Current Relay Pdf Relays with this principle are called directional relays. for example, overcurrent relays can be made directional by adding above discrimination logic to well known overcurrent logic. such relays are called as directional overcurrent relays. In this technical guide we will walk you through everything you need to know about directional and non directional relays, their working principles, applications, and how they function within substation protection schemes. A directional overcurrent protection operates when the current exceeds the pickup value in specified direction. fault currents abf and dcf flow towards the bus for relays r2 and r5 and away from the bus for relays r3 and r4. Overcurrent directional relays: these relays use the phase difference between the current and voltage to determine the direction of the fault. they are commonly used in power systems with radial or parallel feeders. This document discusses different types of directional over current relays. it explains that directional over current relays operate when fault current flows in a particular direction and will not operate if power flows in the opposite direction. In this post operation of directional current relay along with its settings explained. the detailed explanation about directional relay settings with characteristic angle, maximum torque angle and polarisation voltages are given.
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