There are a variety of concepts by which this task is done. 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.The induction type nondirectional overcurrent relay has a construction similar to a watthour meter, with slight modification.The figure below shows the constructional of nondirectional induction type overcurrent relay. Hence, earth fault directional unit will not pick-up. Lecture -14 Fuse Protection; Lecture -15 Fundamentals of Overcurrent Protection; Lecture -16 PSM Setting and Phase Relay Coordination (Tutorial) Lecture -17 Earth Fault Protection using Overcurrent Relays; Module-5 Directional Overcurrent Protection. h�bbd``b`:$�@���?+���,F$�?㏿ �T� h�b```f``R``d`��� Ȁ �L@9���ߙx10(�O��`����3B�V�1˞p����i�|�n����U���]���J;̺ҟ��Z�j��h�M��(���@#�Kp04Jp4�l��@��A4�@r�ؽb�)��1 �( �"�,�]��b$��@D- ��LN Timing characteristics Instantaneous relay,Definite time lag relay,Inverse time lag relay,Inverse definite minimum time (IDMT) lag relay. It contains two relaying units, over current units and the other a directional unit. Directional overcurrent protection is used when it is necessary to protect the system against fault currents that could circulate in both directions through a system element, and when bi-directional overcurrent protection could produce unnecessary disconnection of circuits. The file takes data read from a Comtrade file and postprocesses it. @`� �8�a��F�> `e`��H��.XD����� 3#���\k�[3``�v �%�y���o�\���xxx��00. The device is provided by the use of extra voltage inputs to the protection relay. They are available with either inverse, very inverse or extremely inverse time characteristics. Directional Overcurrent Ground Relays Types IRP, IRC and IRD For overcurrent unit: Entering the curve in Figure 24 at multiples of pickup equal to 4.6, the closing time for instantaneous over-current is 16 ms. 221 0 obj <>stream INTRODUCTION Directional elements determine the fault direction. It protects the equipment of the power system from the fault current. I. When … They are used to control overcurrent elements, supervise distance elements for increased security, and form quadrilateral distance characteristics. Relays have five current and four voltage inputs they are housed in E6 or E8 cases. To read in a data file remove the table currently at the top of the file. The supply continues overfeeder 1. When short circuit current can go in both directions through the protection relay location, it may be required to make the response of the protection relay directional by the initiation of a directional control device. Current Polarization: For providing direction feature in earth fault relay we can also use current as refrenec phasor which is called current polarization. Directional overcurrent protection The assemblies for phase-overcurrent protec-tion contain RXPDK 21H as directional relay. A and B are nondirectional overcurrent relays while C and D are directional relays. Abstract – Directional overcurrent relaying (67) refers to relaying that can use the phase relationship of voltage and current to determine direction to a fault. But in a loop as shown in fig 19.1, the last relay to be MiCOM P123, P126 & P127 can indicate the phase(s) in fault by configuring output relays (first stage only) Three-phase & earth-fault directional overcurrent (67/67N) Each of the three-phase overcurrent stages of P127 & earth fault stages Title: Two vs. Three Overcurrent Elements for Phase Fault Protection in Feeder Relays Author: GE Power Management Subject: Application Note Keywords: F35, F60, 750/760 The device is provided by the use of extra voltage inputs to the protection relay. Application Directional relay assemblies are used for overcurrent or earth fault protection when selectivity is required, e.g. Learn more about Chapter 7: Directional Overcurrent Relays on GlobalSpec. The relay typically consists of two elements. (Forward, Reverse) • Directional relays may or may not make use of directionally controlled instantaneous units. 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