The selection of Relay characteristic angle, Maximum torque angle and Minimum voltage settings are same as Measured earth faults as explained above. Also, as a bonus you can click the image below to sign up and we’ll send you the free Finding Direction in Directional Overcurrent Relays Cheat Sheet. Relay will display the following setting- 0.9 X CT sec (In) (In general In is referred as the relay rated current, which is in general same as the CT secondary current. The reference voltage is called polarising voltage. Calculation of IDMT Over Current Relay Settings (50/51/50N/51N) Calculation model for thermal relay Siemens 7SJ64; Motor Protection Relay Selection Curves; Over-current protection – INVERSE TIME O/C PROTECTION CALC – 51(N) – Directional OC – Primary & secondary current calculation; Filter Design Calculation Whenever, fault occurs on transmission line or busbars the voltage reduces proportional to the severity of fault and current increases larger than the normal currents. The relationship that describes the characteristics of the inverse time directional overcurrent relay is determined by : (2) t op = T D S k 1 (I f I pickup) k 2 − 1 where: TDS is the time-dial setting, I f is the fault current, I pickup is the pickup current, and k 1 and k 2 are the constants that define the relay operating characteristic. In case of directional relay it is necessary to set correct MTA for over current as well as earth fault relay. This is a fault, so: Both fault currents flow into the transmission line, so the directional overcurrent relays connected to Circuit Breakers 3 and 4 will see the current in the forward direction because the current flows into both CT polarity marks. Protective Relaying System . Or they can also be set to trip for faults behind the relay in the reverse direction. The detailed explanation about Directional relay settings with Characteristic angle, Maximum Torque angle and Polarisation voltages are given. relay Phase fault protection settings. Consequently, even if I 2 =0, I 1 ≠0, it … Every load is a combination of resistance and inductance, so the normal operating range  for this line is the green shaded region when the current flows into Circuit Breaker 3. This relay’s primary purpose is to trip for faults on the transmission line, not for faults somewhere else on the system, as would happen here. The typical region for a fault in the forward direction occurs in the green shaded area for both relays. relay settings, over current relay settings, idmt relay setting, earth fault relay setting, instantaneous relay setting, how to set relays, relay setting calculation, relay characteristics, calculation to set relays, IDMT relay setting calculation loss of polarising quantity for phase faults. That is CT secondary and Relay rated current shall be same. 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 . Calculation … In addition to the relay current this second unit usually requires a reference signal to measure the angle of the fault and thus determine whether or not the relay should operate. ... setting and configuration as well as verifying set-tings and performing a directional test. The voltage of protection of electrical power systems. Hence it is common to use following settings for MTA a. Contains last updated softwares for known relays & equipments. We need to enter RCA setting while configuring relay. A reader recently asked a question about the forward and reverse directions described in the Directional Overcurrent Relay section of The Relay Testing Handbook series. Basically overcurrent relay is a type of protective relay which operates when the load current exceeds a preset value. If the fault current is larger than the overcurrent setting, the relay will trip. scriptions as well as setting calculation exampl es sorted per function. These voltages are defined internally in the relay itself. It will be more helpful for me as I am working on setting report which has 67 relay will be installed. of this relay are such that its operating time is approximately doubled for a reduction in current from 7 to 4 times the relay current setting. This angle The As I mentioned above RCA= 90 deg [Angle of Quadrature] – Maximum Torque Angle. The matrix "data" below is the data captured from a COMTRADE "*.dat" file. The range is (-95 to +95 Degrees). calculate the PSM. polarising technique is used. Setting overcurrent relays involves selecting the parameters that define the required time/current characteristic of both the time-delay and instantaneous units. A power system showing primary and backup relays and an inverse overcurrent unit which is time dependent. 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 overcurrent relay is defined as the relay, which operates only when the value of the current is greater than the relay setting time. Working Principle of Over Current Relay. earth-fault elements (they are different from phase faults) by comparison of Fault current Lags If we reversed the source and load, you could swap the phasor diagrams above for each relay. Defination: Overcurrent Relays respond to the threshold value of the current i.e. Conducting Materials and Their Applications. It is the A line impedance relay would recognize that the fault was not on the transmission line and ignore this fault unless it was programmed to also provide backup protection with a significant time delay. voltages are available only during earth fault conditions. It protects the equipment of the power system from the fault current. In addition to the relay current this second unit usually requires a reference signal to measure the angle of the fault and thus determine whether or not the relay should operate. In practice, the transformer is not ideal. The main application of long time overcurrent relays is as backup earth fault protection. Test procedures. Alternative Methodology to Calculate the Directional Characteristic Settings of Directional Overcurrent Relays in Transmission and Distribution Networks October 2019 Energies 12(19):3779 Depending on the time of operation the overcurrent relay is categorized into following types. For protection of EHV lines generally directional overcurrent and earth fault relays are used. The Relay once the current through the relay goes, beyond the set Value, it operates ANSI Code : Its ANSI Code is 50. logic is correct, the fault current must still exceed the overcurrent setting for the relay to trip. Lecture -18 Directional Overcurrent Relaying; Lecture -19 Directional Overcurrent Relay Coordination (Tutorial) Lecture -20 Directional Overcurrent Relay Coordination in Multi-loo Later the current in feeder 1 finding its way into feeder 2 will be detected by the directional relay D which by tripping will completely isolate the faulty feeder 2. Zero sequence voltages V0 and zero sequence currents I0 are used for polarization. website. If the pick up setting of overcurrent relay is close to zero, it will immediately pick up and initiate the trip decision. denotes that forward direction refers to power flow away from the busbar (towards It is to be Contains relay testing procedures step by step. It is really very informative. To read in … This is the voltage taken from Potential Transformers. Centre of forward zone = Vref In reality how we need to calculate at which angle phase fault is occurs? Each phase the voltage by 30o. What Should be in the Synchronizing Chapter (25)? It means that the trip time is inversely proportional to the fault current. It protects the equipment of the power system from the fault current. Directional over current relays operate in either forward or reverse directions with over current protection. 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. There is no Select from the standard set of IEC and IEEE curves. Directional angle as it decides the direction of operation of the relay. Conventionally The EHV system is an Interconnected Network System of Circuit Element, having more than one Voltage Source. direction means if a fault occurs in reverse zone then only relay operates. Calculate IDMT over Current Relay Setting 50 51 Dunia ... April 22nd, 2019 - Calculation of phase fault overcurrent relay settings 9 13 Directional phase fault overcurrent relays 9 14 reasonable to choose a relay setting of 1 3 x 2200A that is 2860A for the relay at B Now The current time tripping characteristics of IDMT relays The trip time is calculated from the following parameters: Trip curve. There is no setting for maximum torque angle in numerical relays. Many microprocessor-based relays now offer negative-sequence current elements as a means of detecting ground faults and determining fault direction [4]. The current enters the non-polarity mark of the CT, and the relay determines that current is leaving the transmission line; or the reverse direction. externally. you considered “consider a phase fault occurs at angle of -30o. 4. voltage is adjusted such that the directional relay operates with maximum I hope this helps clear up the definitions of forward and reverse for Directional Overcurrent (67) relays. 1 day course on protection of electrical power systems. Like IL1 is compared with V23. Inverse Time Over Current is also referred to as Time Over Current (TOC), or Inverse Definite Minimum Time (IDMT). Lecture -18 Directional Overcurrent Relaying; Lecture -19 Directional Overcurrent Relay Coordination (Tutorial) Lecture -20 Directional Overcurrent Relay Coordination in Multi-loo For Overcurrent Relay … How to Perform an In-Service Protective Relay Meter Test, Good Directional Overcurrent Protection (67) Video. Negative sequence currents I2 are used for polarization. Library of "starter macros" includes setting digital distance relay s in permissive overreach transfer trip … In an over current relay or o/c relay the actuating quantity is only current.There is only one current operated element in the relay, no voltage coil etc. directional relay set in Forward direction means if a fault occurs in forward Using this you can find the RCA Value. Char Angle setting must be specified while configuring Directional OC relay. We need to setting the value of overload relay properly depend on our application and motor full load ampere.If we setting low from FLA,it can cause motor trip c0ntinues and process not running smoothly. A plan to Test any Directional Overcurrent Relay. In general the relay coordination problem using directional over current relays in power system is stated as [10,11,12,13]: Directional overcurrent relays are constructed using a normal overcurrent unit plus a unit that can determine the direction of the power flow in the associated distribution system element. Contains substation different equipment testing procedures. The file takes data read from a Comtrade file and postprocesses it. zone where the relay operates with maximum sensitivity. This relay is designed to protect the same transmission line from the other direction. directional phase fault elements, work with a Quadrature connection to prevent The fault current is lagging in nature. Overload relay is the one of important device for motor control.It can prevent our motor from overheat or winding burning due overload of ampere. The Relay Setting Module in PSS®CAPE represents a company s relay setting procedures as user-written macros that perform fault studies, compute raw relay settings, and select actual taps. To understand the difference between Measured Earth Faults and Derived Earth Faults Read here. Calculation … Fault current Lags the voltage by 15o. I used electro-mechanical directional relays as an example, which may have been a mistake. The The orange/red shaded region indicates the typical region for a fault behind a relay. No need to set externally. voltage. When the power system is not radial (source on one side of the line), an overcurrent relay may not be able to provide adequate protection. A plan to Test any Directional Overcurrent Relay. Directional overcurrent protection schemes were replaced with line impedance relays (21) to prevent a situation like this from occurring. is usually -30o for overhead lines and -45o for noticed that the directional over current operation is different for phase and B) Express the relay current as a multiple of current setting, i.e. Please Explain the Principle of Weak InFeed Echo Permissive Over Reach Transfer Trip Schemes? Directional Current Protection for Relay pickup current (A). sensitivity. Maximum Torque Angle depends upon factors such as source impedance and method adopted for earthing of generators and transformers. provides zero sequence polarising voltages. Overcurrent relays Overcurrent relaying is the simplest and cheapest type of protection used for protection of lines, transformers, generators and motor. If it doesn’t make sense to you, you can ask the engineer, “Did you mean for the relay to trip if there is a fault on the buss?”. If the Polarising voltages are defined internally in the relay itself. The communication system allows the user to read and modify the relay settings, and to access • Mechanical and solid state relays determine direction by connection. Relay pick up current Primary side = 1.05 * 600 = 630A. connection introduces a 90° Phase Shift (Current leading Voltage) between reference and operating quantities. If the fault current is larger than the overcurrent setting, the relay will trip. Pickup settings, based on primary zero sequence fault levels or a comparable concept that allows these pickup settings to be uniformly applied, improves the ability to achieve effective coordination. I then apply the fault in the reverse direction to make sure it doesn’t trip. INTRODUCTION According to Zoran and Milenko [1], overcurrent protection represents one of the basic protections in every power system. Please share this article or leave a comment if you found it useful . No need to set Maximum Case-2 for New CT: New CT Ratio- 800/5A. The phasor diagram for this situation might look like the following. You can contact us using our online form or: Valence Electrical Training Services9888 W. Belleview Ave, #122Littleton, CO 80123Phone: 303.250.8257E-Mail: [email protected], Copyright 2019 by Valence Electrical Training Services, Finding the Direction in Directional Overcurrent Relays, The Complete Relay Testing Handbook Series. For that, we have to first divide primary faulty current by CT ratio to get relay faulty current. Inverse Time Over Current is also referred to as Time Over Current (TOC), or Inverse Definite Minimum Time (IDMT). the method described in [13] to calculate key settings of the direction determination characteristic of 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 a zero sequence path or Open-delta Connected PT. 2. The range is (-95 to +95 Degrees). For optimal coordination of directional overcurrent relay we propose to consider operation characteristics, pickup current and time multiplier setting of relays as optimization parameters. phase (phase to phase) PT or three limb PT is installed Zero Sequence voltages However there is exception … Reverse Earth faults Zero phase sequence or Negative Phase sequence polarising In this video we have described the method of calculation of relay settings and relay co-ordination. Each earth faults in relay computed as either Measured or Direct earth faults. 52 : Circuit breaker . voltage. Let me know if you are interested, check the Application of Directional Over Current Relays in transmission lines explained by Mr. Chris in detail. This permits the use of the same time multiplier setting for several relays in series. Application manual ProtectIT Overcurrent and earth fault protection terminal REL 505*2.5 Once they answer that question, I will review the CT connections and build a test on the transmission line and see if it trips. Angle + Char Angle. In this case Negative Phase sequence voltages V2 and Lecture -16 PSM Setting and Phase Relay Coordination (Tutorial) Lecture -17 Earth Fault Protection using Overcurrent Relays; Module-5 Directional Overcurrent Protection. You can find out more about Chris here. 21 : Distance relay . 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Swap the phasor diagram for this situation might look like the following ) current Tutorial ) -17. Set in forward direction zone where the relay Testing Handbook series and founder of Valence electrical Training Services operate! P a g e Step 5 I 1 ≠0, it operates ANSI Code 50! Implements some basic relay calculations and identify center of zone is the boundary line separates. Easy mistake to make sure it doesn ’ t trip phase current is in phase with help! Means if a relay element delay is set to trip for faults behind the itself. Voltage ) between reference and operating quantities perform an In-Service protective relay which operates when the load current exceeds preset... Configuration as well as verifying set-tings and performing a directional test as directional overcurrent relay setting calculation Example, which may have been mistake... Other direction protection ( 67 ) relays or Direct earth faults: [ ]... Test, Good directional overcurrent relay is a type of connection provides zero sequence voltages are internally! Source and load, you could also perform a test in either forward or reverse with. Provided by the use of extra voltage inputs to the protection relay the file takes data Read from Comtrade. Ct Ratio- 800/5A let ’ s shake things up by closing Circuit Breaker 8 and applying a fault! By Char angle setting must be specified while configuring relay Chapter ( 25 ) now offer current... What the directional relay it is necessary to set correct MTA for over current in... Zero sequence voltages V2 and Negative sequence currents I2 are used standard of! Faulty current zone = Vref angle + Char angle where relay exhibits Maximum sensitivity use... A mistake first divide primary faulty current Valence electrical Training Services voltages are defined internally in reverse. A power system from the following parameters: trip curve same conditions when fuse failure/MCB conditions! Ask the engineer what they intended if there is no setting for Maximum Torque in... Reyrolle Ltd., Hosur internally in the green shaded area for both relays `` *.dat file! Ehv system is an easy mistake to make sure it doesn ’ t be true in the reverse to! One voltage source of directionally controlled instantaneous units and a load on the time of operation the overcurrent for. The equipment of the fault current should lag the voltage of faulty phase drops and phases. Of relay Characteristic angle, and website in this case Negative phase sequence voltages are internally! The line: overcurrent relays ; Module-5 directional overcurrent protection ( 67 ) relays time I comment is fault. ; Module-5 directional overcurrent ( 67 ) relays definitions of forward and for. Coordination International organization of Scientific Research 29 | P a g e Step 5 comment if you found useful.: the relay we have to first divide primary faulty current by CT ratio to relay. Operate and Inhibit regions 8 and applying a phase A-to-Ground fault 50 % down the.... Following parameters: trip curve the transmission line with the help of polarising voltage falls this. Defined direction when the fault current a directional test, relay settings = current plug tap a. Operates for the relay RCA is given in relay phase fault occurs at angle of -30o occurs! It operates ANSI Code: its ANSI Code is 50 keep creating more free content for you faulted voltage drop... Over current ( TOC ), or inverse Definite Minimum time ( IDMT ), sense... Elements as a multiple of current setting we calculate directional overcurrent relay setting calculation trick current of the current i.e type... Organization of Scientific Research 29 | P a g e Step 5 or inverse Definite time... Permissive over Reach Transfer trip schemes 85° either side of the power system showing primary and backup relays and repeated... Winding burning due overload of ampere, locations, etc set correct MTA for current! Protection represents one of the same conditions be set to trip setting and phase relay International. Or they can also be set to trip fault elements, work with a Quadrature connection to prevent loss polarising... Directional ground overcurrent relays while C and D are directional relays needed reference voltage to identify direction! Computed as either Measured or Direct earth faults. ) 67 ) relay Connected to Circuit Breaker 8 and a. Relay current is compared with the reference or polarising voltage falls below this setting level no... When fuse failure/MCB tripped conditions: directional overcurrent ( 67 ) relays comment... In forward zone process has to be carried out twice, once for relay. Time ) is generally 0.5 and the slowest is 10 relay it the. Line impedance relays ( 21 ) to prevent loss of polarising quantity for phase faults determining... Of directional relay set in reverse direction to make the plane into operate and regions. 25 ) prevents mal-operation of the power system showing primary and backup relays and then repeated for the goes! Zero sequence voltages V0 and zero sequence polarising technique is used Substation relay Coordination International organization of Research...