The device is provided by the use of extra voltage inputs to the protection relay. The obtained voltage and current were then used to determine the operation of directional overcurrent and earth-fault relay. Consider the network shown in fig. The relay setting is 50% to 200% in steps of 25%. Multiple application items are discussed and include topics from pick-up and time-delay determinations to topics about ground source issues and the use of negative sequence overcurrent elements. If pickup current of relay is considered as a fixed parameter, problem is considered as a linear programming problem and it is solved for finding optimum time multiplier setting (TMS) of directional overcurrent relay . Differential protection scheme is based on comparison of measured variables such as current and voltage at the two ends of a line via a communication channel such as pilot wire. A definite time overcurrent relay can be adjusted to issue a trip output at an exact amount of time after it picks up. When directional overcurrent protection relays are included at the load end of a set of parallel feeders fed from an AC power source, a minimum fault-current threshold is specified based on the potential of a phase-to-phase fault at the source to cause a relay to operate misleadingly. For obvious reasons of obtaining selectivity overcurrent relays are made directional. This guide covers all of our true power relays as distinguished from directional power and direc-tional overcurrent relays. Constructional Details and Operation of Non Directional Over Current Relay (Wattmeter Type) A directional over current relay operates when the current exceeds a specified value in a specified direction. Directional relays (67, 67N) are required to perform this function. Figure Fig. Normal over current or earth fault relays will trip the cb for all faults, ie. In a typical application, the over current relay is connected to a current transformer and calibrated to operate at or above a specific current level. The presented rules apply to all overcurrent relays and protection functions of SPACOM and RED 500 protection relays. This is the point where the relay residual voltage polarizing input is connected. (4) Long Time Inverse over current Relay: The main application of long time over current relays is as backup earth fault protection. The authors declare no conflicts of interest. Relay Characteristic Angle: RCA; The characteristic angle is the phase angle by which reference or polarising voltage is adjusted such that the directional relay operates with maximum sensitivity. 2 Purpose Application of Directional Overcurrent and Earthfault Protection-January 2004 Relay Connection Angle The angle between the current applied to the relay and the voltage applied to the relay at system unity power factor e.g. Inverse Time Over Current Relay. “the degree of certainty that a relay or relay system will operate correctly” – dependability. It contains two relaying units, over current units and the other a directional unit. It is of two types: instantaneous over current (IOC) relay and definite time overcurrent (DTOC) relay. The selection of current transformer and suitable relay settings are described with an example. 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. Overcurrent Relays/Elements; Directional Overcurrent Relays; Over/under Voltage Relays; Distance Relays; Day 3 Out-of-Step Relaying. Standard overcurrent relays cannot distinguish the direction of the current flow. 1. Inverse time is a natural character of any induction type rotating device. The block diagram of the inverse-time overcurrent relay is shown in the figure. n Due to time constraints we will discuss Positive and Negative Polarization is the method used by the relay to determine the direction of current flow. Directional over current or directionalal earthfault relays are used in Transmission lines. directional overcurrent protection applications. n Because the relay contains all directional elements (both phase and ground), the application of the proper voltages, currents and phase angles can be challenging. Overcurrent directional relays can be set to trip for faults in the forward direction, which will protect the equipment in front of the relay. IEEE C37.2, 2008. In power systems relays are used to detect abnormal conditions. Journal of Computer and Communications, 2, 103-111. doi: 10.4236/jcc.2014.29014. The relay operates for the defined direction when the fault current is in the same direction and exceeds the over current setting value. This scheme is preferred and extensively used in distribution feeder The study of directional overcurrent relay and directional earth-fault protection application for 33 kV underground cable system in Malaysia Depending on the time of operation the overcurrent relay is categorized into following types. Consequently, additional protective measures are needed here. Thus, it has a time setting adjustment and pickup adjustment. In general the relay coordination problem using directional over current relays in power system is stated as [10,11,12,13]: An important concept in the application of directional overcurrent relays is polarization. fault relative to relay and only slight-ly upon system generation setup. Directional relay senses direction of power flow by means of phase angle between V and I. Application; Uses and Benefits; Hands on Testing of Relays. Committee on the application of directional ground overcurrent relays for transmission lines. Target Seal-in-unitsare provided for the time and instantaneous overcur-rent units and are rated 0.2/2 A. The ANSI device number is 50 for an IOC relay or a DTOC relay. Reyrolle 7SR45 The Reyrolle 7SR45 Argus self-powered/dual powered non-directional overcurrent and earth fault relay is developed using the latest generation of hardware technology and is available in multiple variants depending on the current transformer (CT), binary input/binary output, power supply, and communication configuration. (D) Directional Over current Relays. In other words, we can define reliability as the … IEEE C37.2, 2008. and “the degree of certainty that a relay or relay system will not operate incorrectly” – security. Application Directional phase fault protection (IBC) Protection and Control Time overcurrent Features Mechanical targets 3 inverse time/current operating characteristics Faults on either side. Application Notes 2.1 Overcurrent and Undercurrent Protection 2.1.1 Non-directional Overcurrent Protection GRD140 provides distribution network protection with four-stage phase fault and earth fault overcurrent elements OC1 to OC4, EF1 to EF4, sensitive earth fault elements SEF1 to SEF4, and Application of Overcurrent Relay in Power System directional-unit contacts control the operation of the overcurrent unit (directional control), APPLICATION PHASE FAULT-mC The Type IBC relays are frequently applied for phase-fault protection of a single line. Keywords: current transformer, overcurrent protection, short circuit 2.6-3. 4: Network map with non-directional, maximum-overcurrent time protection relay. For optimal coordination of directional overcurrent relay we propose to consider operation characteristics, pickup current and time multiplier setting of relays as optimization parameters. Conflicts of Interest. It protects the equipment of the power system from the fault current. 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. The quad­ rature and 60-degree connections are us e d with these relays because the fault currents are us-ually highly lagging. 751) follow essentially the same directional relay concepts and principles with a few added twists and turns. Non Directional relay: When there is fault in power system, power flows through fault. Page 19: Figure 2.6-3 Application Of Directional Overcurrent Protection 7SR210 & 7SR220 Applications Guide Directional overcurrent elements allow greater fault selectivity than non-directional elements for interconnected systems where fault current can flow in both directions through the relaying point. The disadvantage here is that a fault in the vicinity of the feed point, where the tripping time t > is longest, results in the highest current. Most ground directional overcurrent relays can be thought of as having two components, a directional component and an overcurrent component. A GUIDE TO THE APPLICATION OF POWER RELAYS FOR THE DETECTION OF OVERPOWER OR REVERSE POWER CONDITIONS ON A POWER SYSTEM by Kenneth Winick Switchgear Equipment Engineering Department General Electric Company Philadelphia, Pa. Be sure to check the instruction book of the overcurrent relay for these details. The overcurrent relay is defined as the relay, which operates only when the value of the current is greater than the relay setting time. When the phase angle between V and I exceeds certain predetermined value, the directional relay operates with a condition that the current is above the pick-up value. Certain relays in … For example, over current, under voltage, fault conditions etc. directional idmt relay suitable for over current or earth fault application si characteristics vi characteristics ei characteristics cdd21 cdd23 cdd24 single phase electromechanical directional idmt and non directional high set instantaneous relay suitable for over''9 overcurrent protection for phase and earth faults fecime When the power system is not radial (source on one side of the line), an over current relay … Overcurrent Relay Torque-Control If you are using a 425 series directional relay to torque-control overcurrent relay, you must determine the method of torque-control employed. 2. One such application is generator protection, where an overcurrent relay monitors the amount of current at the point where an electrical power generator connects to a larger network of generators. DIRECTIONAL OVERCURRENT RELAY. 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