9170900990 Rev H BE1-67 Introduction i INTRODUCTION This instruction … XXX XXX XXXXX R Publication: 9170900990 Revision: H 08/07 www . The reason that Directional overcurrent has a “Relay Characteristic Angle” or “Torque Angle” (a legacy term), is to account for the reactance of your network. This directional over current relay employs the principle of actuation of the relay, when the fault current flows into the relay in a particular direction. However, in a system with multiple sources or parallel paths, we require earth fault relays to be directional as discussed in earlier post How to Incorporate Directional Featurein a Relay.. As we discussed in earlier post How to Incorporate Directional Feature in a Relay, that for making a Relay directional we need Reference Phasor. Three-phase Directional Overcurrent (67) Each one of the three-phase overcurrent stages of the P127 can be independently configured as directional protection with specific relay characteristic angle (RCA) settings and boundaries. By This p roduces a retarding effect on … In order to be able to measure the fault direction, the polarisation variable (the voltage) must have a sufficiently high value. In the previous post about Directional Overcurrent relay (67) testing (Finding the Direction in Directional Overcurrent Relays), we reviewed Directional Overcurrent protection from a system perspective to enhance the descriptions in The Relay Testing Handbook: Principles and Practice.We’ll be looking at Directional Overcurrent relays from a testing perspective in this post. It is the angle between the normal to the tripping plane and the polarisation variable. com. In order for a trip to occur, the magnitude of the operate quantity exceeds the threshold limit for a specific duration and the direction of the fault must be within the operate (trip region) characteristic for a trip decision. 4. Directional Characteristic Angle of Directional Overcurrent Relays in Transmission Networks José Jaramillo Serna Universidad de Antioquia ... and more specifically, the determination of the directional characteristic angle, to the application of the so-called typical settings. If the relay ‘detects fault’ and current leads VR (= Vp), then inhibit the relay tripping. Characteristic Angle is also called Directional angle as it decides the direction of operation of the relay. The differences between the various models covered by this instruction book are shown in Table 1. You can assume that if the forward angle drifts based on reactance, then a similar drift will happen in the opposite direction. Directional Overcurrent Relays Types IBC, IBCG And mcv ,DEVICE FUNCTION NUMBERS FOR USE WITH EXTERNAL DIAGRAMS 52 Power Circuit Breaker 67 - Directional Overcurrent Relays, Type mc or Type mcv 67N - Directional Ground Relay, Type mCG a - Auxiliary Contact, 0;> en when Breaker Opens Dill - Directional Unit SI - Seal-in Unit with Target pdf. Directional Static Overcurrent Relays: For obvious reasons of obtaining selectivity overcurrent relays are made directional. This is expected fault angle, and completely predictable. The scale constant I s is equal to the rated current Ir times the sum of the set value of the switches S1:1, S1:2 and S1:3 plus 0,1. Using field and laboratory data, this paper reviews fundamentals, discusses the limits to sensitivity, and shows how and why directional element designs have progressed. Relay characteristic angle (directional protection) Polarizing Voltage Threshold (directional protection) 2nd element Definite Time Tripping characteristic 3 X CT Pick-up 3 x I n CT primary 100 ms Trip time delay Table 1: Relay parameters for this example . com. This angle is different for phase faults and earth faults. We know that I 0 = (Ia + Ib + Ic) / 3. Overcurrent protection can have a directional or non-directional trip characteristic. Overcurrent is used for automatic testing of directional and non-directional overcurrent relays with auto-assessment of the trip time characteristic, the directional boundaries of the current stages, and the pick-up/drop-off ratio. directional overcurrent relays, such as the relay characteristic angle, the selection of the polarizing quantities (negative sequence or zero sequence) for the directional ground overcurrent protection function, and the minimum thresholds for the activation of the voltage memory for the directional phase overcurrent element. The ‘discrimination principle’ based on phase angle comparison between a set of phasors, one of which is used as reference is called ‘Directional Discrimination Principle’. ElectricalPartManuals . characteristic impedance angle. In this article, we explain some of the concepts behind directional Earth Fault, sharing our experience to support field deployment of this valuable protection element. 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