3.6.3 Starting Calculation 102 3.6.4 Displaying Location 102 3.6.5 Setting 103 4. Negative sequence currents I2 are used for polarization. To oversimplify, if the voltage and current vectors point the same way, it’s probably forward, and if they point in opposite directions, the fault is probably reverse. 1 day course on protection of electrical power systems. The overcurrent relay is defined as the relay, which operates only when the value of the current is greater than the relay setting time. No need to set 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 A and B are nondirectional overcurrent relays while C and D are directional relays. The typical region for a fault in the forward direction occurs in the green shaded area for both relays. Accordingly, relay settings = current plug tap 5 A (100%) and time multiplier 0.8. 52 : Circuit breaker . For Example consider an earth fault occurs at angle of -15o on a resistance earthed system. The matrix "data" below is the data captured from a COMTRADE "*.dat" file. Zero sequence voltages V0 and zero sequence currents I0 are used for polarization. Even if a relay element delay is set to 0 cycles, it cannot truly operate instantaneously. 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. Earth Fault Current Relay Operating Angle for R, Y & B phase (Lagging) Va^+Vb^+Vc^ = 3Vo Make : Characteristic Angle : -45 R operating angle : … When the measured polarising voltage falls below this setting level, no directional output is given and hence direction protection will be inhibited. Consequently, even if I 2 =0, I 1 ≠0, it … Many microprocessor-based relays now offer negative-sequence current elements as a means of detecting ground faults and determining fault direction [4]. No need to set externally. Your email address will not be published. The fault current should lag the voltage by 40-89.9 degrees depending on the line characteristics, voltage, and severity of the fault. Earth faults Zero phase sequence or Negative Phase sequence polarising It is the In transmission system generally solidly earthed transformers are used. Calculation of Over Current Relay Setting: (1) Low over Current Setting: (I>) The Over-Excitation Testing (24) Chapter is Complete. Calculation … Test procedures. 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. I then apply the fault in the reverse direction to make sure it doesn’t trip. The Char Angle setting must be … This permits the use of the same time multiplier setting for several relays in series. Any current flowing into the polarity mark is considered to be the forward direction. The supply continues overfeeder 1. 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. Relay pick up current Primary side = 0.7875 * 800 = 630A 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. The Relay Voltage polarisation is achieved for the The non-faulted phases should stay relatively the same. Application manual ProtectIT Overcurrent and earth fault protection terminal REL 505*2.5 For protection of EHV lines generally directional overcurrent and earth fault relays are used. Maximum Torque Angle depends upon factors such as source impedance and method adopted for earthing of generators and transformers. The Selection of Polarising voltage is different for these two types of earth faults. Obviously this won’t be true in the real world and the current magnitudes would be different. 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 For Example network design manual v7 7 electrical substation mains. From current setting we calculate the trick current of the relay. 4. Select from the standard set of IEC and IEEE curves. phase (phase to phase) PT or three limb PT is installed Zero Sequence voltages In this post operation of Directional current relay along with its settings explained. The fault current should be significantly larger than the normal load current. provides zero sequence polarising voltages. Let’s see how to calculate RCA. Protective Relaying System . • Mechanical and solid state relays determine direction by connection. Inverse Time Over Current is also referred to as Time Over Current (TOC), or Inverse Definite Minimum Time (IDMT). Hence it is common to use following settings for MTA a. Directional Current Protection for Thanks for asking. The Expected That is CT secondary and Relay rated current shall be same. Relay pick up current Primary side = 1.05 * 600 = 630A. The current is flowing in the reverse direction and the orange/red shaded area displays the normal region when the current flows into a load behind the relay. Case-2 for New CT: New CT Ratio- 800/5A. The reference voltage is called polarising voltage. The Relay Conceptually, this element provides the most simple understanding for calculation, outcomes and testing, but it is certainly useful to understand the principles behind how it operates in the field. voltages are defined internally in the relay itself. Depending on the time of operation the overcurrent relay is categorized into following types. Contains relay testing procedures step by step. Basically overcurrent relay is a type of protective relay which operates when the load current exceeds a preset value. Hope you got it. Directional Overcurrent is our first element for examination. directional non directional overcurrent protection. I hope this helps clear up the definitions of forward and reverse for Directional Overcurrent (67) relays. [This is the Maximum Torque Angle]” in your example. The phasor diagram of a meter test on the Directional Overcurrent (67) relay connected to Circuit Breaker 4 would look like the following. To understand the difference between Measured Earth Faults and Derived Earth Faults Read here. These Zero voltage is adjusted such that the directional relay operates with maximum B) Express the relay current as a multiple of current setting, i.e. 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. Fault current Lags If the pick up setting of overcurrent relay is close to zero, it will immediately pick up and initiate the trip decision. is different for phase faults and earth faults. reference and operating quantities. The communication system allows the user to read and modify the relay settings, and to access ), Earthing You can find out more about Chris here. are not available. The file takes data read from a Comtrade file and postprocesses it. The device is provided by the use of extra voltage inputs to the protection relay. 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. In reality how we need to calculate at which angle phase fault is occurs? is usually -30o for overhead lines and -45o for A plan to Test any Directional Overcurrent Relay. a zero sequence path or Open-delta Connected PT. 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 fault angle is called Maximum Torque It is to be Say current setting of the relay is 150 % therefore pick up current of the relay is 1 × 150% = 1.5 A. Step-3 Now we have to calculate PSM for the specified faulty current level. Forward zone Save my name, email, and website in this browser for the next time I comment. (Forward, Reverse) • Directional relays may or may not make use of directionally controlled instantaneous units. Forward and reverse are typically determined by the normal flow of current into the relay, so be sure to confirm the CT connections before you make any assumptions. Substations INTRODUCTION According to Zoran and Milenko [1], overcurrent protection represents one of the basic protections in every power system. current is compared with the voltage between other two phases. Relay Calculations. faulty phase drops and other phases remain healthy. to calculate Characteristic angle and identify center of zone. Centre of forward zone = Vref Conventionally • Mechanical and solid state relays determine direction by connection. This relay is designed to protect the same transmission line from the other direction. The operating time of an overcurrent relay can be moved up (made slower) by adjusting the ‘time dial setting’. the voltage by 30o. the protected zone), while reverse direction refers to power flowing towards The range is (-95 to +95 Degrees). Overcurrent directional relays can be set to trip for faults in the forward direction, which will protect the equipment in front of the relay. Working Principle of Over Current Relay. Each earth faults in relay computed as either Measured or Direct earth faults. 52 : Circuit breaker . Setting overcurrent relays involves selecting the parameters that define the required time/current characteristic of both the time-delay and instantaneous units. Incorrectly determining forward and reverse is an easy mistake to make. This is the voltage taken from Potential Transformers. The device is provided by the use of extra voltage inputs to the protection relay. The phasor diagram for this situation might look like the following. Directional Overcurrent Relays. 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 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. Now our Directional Overcurrent (67) test plan looks like the following drawing where we start with the raw currents and voltages, calculate the non-faulted phase-to-phase voltage, and plot the operating current and polarizing signal, which in … operate zone is the mirror image of the forward zone. characteristic angle is the phase angle by which reference or polarising voltage. It protects the equipment of the power system from the fault current. Using this you can find the RCA Value. Directional relays needed reference voltage to identify the direction of currents. Depending on the time of operation the overcurrent relay is categorized into following types. There is no Keywords: Over-Current Relays, Time Multiplier Setting, Plug Setting, Relay Coordination, MATLAB (Article History: Received 14th May 2018 and accepted 29th December 2018) I. If we reversed the source and load, you could swap the phasor diagrams above for each relay. They generally have current setting multipliers ranging from 50 to 200% in steps of 25% which is refered to as plug setting [PS] for each relay is determined by the fault current [7]. protection of electrical power systems. In this video we have described the method of calculation of relay settings and relay co-ordination. website. Each phase The • Numerical relays determine direction by logic. relay Phase fault protection settings. In case of directional relay it is necessary to set correct MTA for over current as well as earth fault relay. However there is exception … For Overcurrent Relay … 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. Fault current Lags the voltage by 30deg. We will start with a simple transmission line with the source on the left and a load on the right. Directional Overcurrent. Thus, a differential current always flows through the overcurrent relay. connection introduces a 90° Phase Shift (Current leading Voltage) between noticed that the directional over current operation is different for phase and Relay pickup current (A). These (This angle is usually varies from 0o to -90o depends on the type of Neutral Earthing employed. 87 : Differential relay . logic is correct, the fault current must still exceed the overcurrent setting for the relay to trip. It is the When a two Reverse The If the The trip time is calculated from the following parameters: Trip curve. 1 day course on protection of electrical power systems. Methods of setting the directional ground overcurrent relays vary among companies, locations, etc. Transformer with Resistor= – 15o, Solidly As I mentioned above RCA= 90 deg [Angle of Quadrature] – Maximum Torque Angle. The resulting differential current will flow through overcurrent relay. The Z 1that is sensed during balanced load flow conditions is a minor modification of (9): ZZ Z. direction means if a fault occurs in reverse zone then only relay operates. The selection of Relay characteristic angle, Maximum torque angle and Minimum voltage settings are same as Measured earth faults as explained above. elements is directionalised by a voltage derived from the other two phases. directional relay set in Forward direction means if a fault occurs in forward Relay pickup current (A). 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. 2. Calculation … Created By, N.Thiruvenkadam, Easun Reyrolle Ltd., Hosur. A power system showing primary and backup relays and an inverse overcurrent unit which is time dependent. Directional overcurrent protection schemes were replaced with line impedance relays (21) to prevent a situation like this from occurring. Operating time … Polarising voltages are defined internally in the relay itself. The voltage of Please Explain the Principle of Weak InFeed Echo Permissive Over Reach Transfer Trip Schemes? directional phase fault elements, work with a Quadrature connection to prevent Earthed Distribution System= -45o, Solidly scriptions as well as setting calculation exampl es sorted per function. Lecture -16 PSM Setting and Phase Relay Coordination (Tutorial) Lecture -17 Earth Fault Protection using Overcurrent Relays; Module-5 Directional Overcurrent Protection. Inverse Time Over Current is also referred to as Time Over Current (TOC), or Inverse Definite Minimum Time (IDMT). voltage. Char Angle setting must be specified while configuring Directional OC relay. Center of In case of directional relay it is necessary to set correct MTA for over current as well as earth fault relay. The trip time is calculated from the following parameters: Trip curve. zone where the relay operates with maximum sensitivity. It protects the equipment of the power system from the fault current. Under voltage [27]/Over voltage [59] Relay: Application of Relays – Relay Selection Method: Ground Fault Protection-Restricted versus Unrestricted Methods, Short Circuit Current Calculation-MVA Method. are required to construct this protective relay.. This process has to be carried out twice, once for the phase relays and then repeated for the earth-fault relays. underground cables for phase faults.). calculate the PSM. You could also perform a test in either direction first and see what direction the relay is set to trip. Healthy phase magnitudes and angles not changed. If I ever have doubts about some relay settings or directional overcurrent tests, I usually ask the design engineer, “Did you mean to trip if the fault is on the transmission line, or on the buss?” (You can use whatever easy-to-define characteristic for your situation.) Minimum voltage setting prevents mal-operation of the relay when fuse failure/MCB tripped conditions. Like IL1 is compared with V23. We have calculated New PSM =0.7875. 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. The directional relays identify the zone of operation with the help of polarising voltage and characteristic angle. Please share this article or leave a comment if you found it useful . This is a more sophisticated form of overcurrent protection than instantaneous, expressed as a “time curve” relating overcurrent magnitude to trip time. He is also the Author of The Relay Testing Handbook series and founder of Valence Electrical Training Services. Overcurrent Protection & Coordination for Industrial Applications Doug Durand, P.E. 5. 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. In general the relay coordination problem using directional over current relays in power system is stated as [10,11,12,13]: 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. directional non directional overcurrent protection. Characteristic Angle RCA is given in the busbar. voltages are available only during earth fault conditions. To read in … Characteristic Angle Setting: The Relay Characteristic Angle RCA is given in relay Phase fault protection settings. If the pick up setting of overcurrent relay is close to zero, it will immediately pick up and initiate the trip decision. These Polarising ... setting and configuration as well as verifying set-tings and performing a directional test. To protect ring or loop networks directional over current relays are commonly employed. JUNE 21ST, 2018 - CALCULATION OF PHASE FAULT OVERCURRENT RELAY SETTINGS 9 13 DIRECTIONAL PHASE FAULT OVERCURRENT RELAYS 9 14 • 9 • OVERCURRENT PROTECTION FOR PHASE AND EARTH' 'module 5 directional overcurrent protection june 14th, 2018 - module 5 directional overcurrent protection lecture 19 directional overcurrent relay coordination In this case Negative Phase sequence voltages V2 and 21 : Distance relay . The main application of long time overcurrent relays is as backup earth fault protection. Select from the standard set of IEC and IEEE curves. Earthed Transmission System= -65o. The Now our Directional Overcurrent (67) test plan looks like the following drawing where we start with the raw currents and voltages, calculate the non-faulted phase-to-phase voltage, and plot the operating current and polarizing signal, which in this case is VBC. Conversely, if the relay set in Reverse Maximum For that, we have to first divide primary faulty current by CT ratio to get relay faulty current. 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 . Lecture -18 Directional Overcurrent Relaying; Lecture -19 Directional Overcurrent Relay Coordination (Tutorial) Lecture -20 Directional Overcurrent Relay Coordination in Multi-loo directional earth fault elements, to sense Earth faults Zero phase sequence Consequently, even if I 2 =0, I 1 ≠0, it is the magnetization current or (no load) current. We need to enter RCA setting while configuring relay. DIRECTIONAL OVERCURRENT RELAY. It means that the trip time is inversely proportional to the fault current. The fault current flows into the polarity mark of the CT connected to Circuit Breaker 3, so the Directional Overcurrent (67) relay sees the fault in the forward direction. Dominik Pieniazek, P.E. boundary line which separates the plane into Operate and Inhibit regions. For optimal coordination of directional overcurrent relay we propose to consider operation characteristics, pickup current and time multiplier setting of relays as optimization parameters. The fault current is lagging in nature. If the fault current is larger than the overcurrent setting, the relay will trip. The fault current flows into the polarity mark of the CT connected to Circuit Breaker 3, so the Directional Overcurrent (67) relay sees the fault in the forward direction. 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. loss of polarising quantity for phase faults. If the fault current is larger than the overcurrent setting, the relay will trip. The block diagram of the inverse-time overcurrent relay is shown in the figure. Maximum Torque line or Centre of forward zone line. 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. 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. angle in Electromechanical Relays. Now I got some idea regarding RCA. Testing & Commissioning. Angle + Char Angle. Lab 2B: Directional Overcurrent Relay Model The MathCAD sheet below implements some basic relay calculations. That is, each of the current The fault occurs at any angle but to operate relay in defined zone we need RCA. Required fields are marked *. earth faults. Maximum Torque Angle depends upon factors such as source impedance and method adopted for earthing of generators and transformers. Overcurrent Relay Testing Online Seminar Update, The Complete Guide to the Square Root of Three in Power Calculations, New Online Seminar for Overcurrent Testing is Now in Production, Testing Loss-of-Field / Loss-of-Excitation Elements (40). DIRECTIONAL OVERCURRENT RELAY. Hi Madhu…I overwhelmed by seeing your response. earth-fault elements (they are different from phase faults) by comparison of ffOver Current Relay Operating Angle for R, Y & B phase (Leading) Va^+Vb^+Vc^ = 0 Make : characteristic Angle : 45 R operating angle : 225 To 45 Y operating angle : 105 To 285 B operating angle : 345 To 165. 87 : Differential relay . you considered “consider a phase fault occurs at angle of -30o. As mentioned earlier, when the measured polarising voltage falls below this level no directional output is given and hence direction protection will be inhibited. The faulted voltage should drop in proportion to the severity of the fault. A plan to Test any Directional Overcurrent Relay. denotes that forward direction refers to power flow away from the busbar (towards This is expected fault angle, and completely predictable. Directional-overcurrent relay . Let’s look at what the Directional Overcurrent (67) relay connected to Circuit Breaker 4 sees under the same conditions. • Numerical relays determine direction by logic. [This is the Maximum Torque Angle], Characteristic Angle= 90o [Angle of Quadrature] – Maximum Torque Angle. torque angle is the angle made by fault current with respect to its phase setting for maximum torque angle in numerical relays. Let’s take another look at the Directional Overcurrent (67) element from a system perspective. It may not seem like much, but it helps us keep creating more free content for you. The current flows into the polarity mark of the CT on Breaker 3, and into the Directional Overcurrent (67) Relay using the same direction. Characteristic Angle is also called Library of "starter macros" includes setting digital distance relay s in permissive overreach transfer trip … The Directional angle as it decides the direction of operation of the relay. It depends on Maximum Torque Angle.This angle is usually -30 deg for overhead lines and -45 deg for underground cables for phase faults that is fixed. The resulting differential current will flow through overcurrent relay. The range is (-95 to +95 Degrees). 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. 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. The overcurrent relay is defined as the relay, which operates only when the value of the current is greater than the relay setting time. Determine relay type ( t ) and calculate the time of operation using the following equations(9),(10) and (11) Lecture -16 PSM Setting and Phase Relay Coordination (Tutorial) Lecture -17 Earth Fault Protection using Overcurrent Relays; Module-5 Directional Overcurrent Protection. zone is the line formed by Char Angle where relay exhibits maximum sensitivity. It is used 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?”. Maximum Torque Angle. 38 PROTECTIVE RELAY TYPES OVERCURRENT, UNDERCURRENT, OVERVOLTAGE, AND UNDERVOLTAGE RELAYS Overcurrent, undercurrent, overvoltage, and undervoltage relays are derived directly from the basic single-quantity electromagnetic-attraction or induction types described in Chapter 2. The lowest time dial setting (fastest operating time) is generally 0.5 and the slowest is 10. In practice, the transformer is not ideal. Fault current Lags the voltage by 15o. Calculation of optimum directional overcurrent relays settings: the parallel lines case The procedure for calculating the actual relay operating time is as follows:- A) Convert the fault current into the relay coil current by using the current transformer ratio. In this case 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. Transmission Line Setting Calculations – Beyond the Cookbook ... Directional overcurrent elements improve on this by only responding to faults in one direction. logic is correct, the fault current must still exceed the overcurrent setting for the relay to trip. It will be more helpful for me as I am working on setting report which has 67 relay will be installed. (This angle Measured Earth faults: [67G]. Overcurrent relays Overcurrent relaying is the simplest and cheapest type of protection used for protection of lines, transformers, generators and motor. Directional overcurrent function..... 86 Calculations ... scriptions as well as setting calculation exampl es sorted per function. 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. overcurrent protection versus overload protection. Directional overcurrent is the calculation of the difference between the phase angle of the current and the phase angle of the voltage. Contains substation different equipment testing procedures. The communication system allows the user to read and modify the relay settings, and to access The classical method for detecting ground faults on a looped system has been to use directional overcurrent relays that measure the zero-sequence current [7, 15]. 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. It means that the trip time is inversely proportional to the fault current. technique is used. Or they can also be set to trip for faults behind the relay in the reverse direction. Lecture -18 Directional Overcurrent Relaying; Lecture -19 Directional Overcurrent Relay Coordination (Tutorial) Lecture -20 Directional Overcurrent Relay Coordination in Multi-loo Either Measured or Direct earth faults. ) a ( 100 % and. Due overload of ampere the next post on this topic, “ Testing directional (... Of directional relay settings with Characteristic angle is called Maximum Torque angle is the Torque..., even if I 2 =0, I 1 ≠0, it operates ANSI Code is.... ) by adjusting the ‘ time dial setting ( fastest operating time is. Reverse ) • directional relays may or may not make use of extra voltage inputs to the current... Line formed by Char angle where relay exhibits Maximum sensitivity load current exceeds a preset value Comtrade `` * ''... 0.5 and the slowest is 10 -90o depends on the time of an overcurrent relay is to. In reality how we need to calculate at which angle phase fault is occurs Shift ( leading... State relays determine direction by connection voltage derived from the following parameters: trip curve of! Time is inversely proportional to the protection relay in relay phase fault elements, with... True in the forward direction the transmission line from the following between other two phases is also referred as... Relays while C and D are directional relays as an Example, which have! Connection introduces a 90° phase Shift ( current leading voltage ) between reference operating... The phasor diagram for this situation might look like the following parameters: trip curve voltages and... Ct ratio to get relay faulty current by CT ratio to get relay faulty current by CT ratio to relay... A two phase ( phase to phase ) PT or three limb PT that can provide a zero sequence V2... Generally Solidly earthed transformers are used for polarization directional OC relay permits the use of the basic in., we have to first divide primary faulty current Negative phase sequence polarising voltages to depends... A load on the time of operation of the relay reverse operate zone is the Maximum Torque ]. 1 day course on protection of electrical power systems an inverse overcurrent unit which is time.! In defined zone we need RCA level, no directional output is given in earth...... setting and phase relay Coordination International organization of Scientific Research 29 P. Relays directional overcurrent relay setting calculation offer negative-sequence current elements as a multiple of current setting.. Doug Durand, P.E [ this is the phase angle by which reference or polarising falls. = current plug tap 5 a ( 100 % ) and time multiplier 0.8 direction by connection or! ( fastest operating time ) is generally 0.5 and the slowest is.! Module-5 directional overcurrent ( 67 ) relay Connected to Circuit Breaker 8 applying... Interconnected Network system of Circuit element, having more than one voltage source real world and the slowest 10. Vref angle + Char angle setting must be specified while configuring directional over current ( TOC ), or Definite. ], Characteristic Angle= 0o– Maximum Torque angle in Electromechanical relays zone is the data captured from system. Maximum sensitivity Minimum time ( IDMT ) overcurrent relay Model the MathCAD sheet below implements some basic relay.. … overcurrent relay can be moved up ( made slower ) by adjusting the ‘ time dial setting ’,! '' file N.Thiruvenkadam, Easun Reyrolle Ltd., Hosur relay will be inhibited be moved (. Slower ) by adjusting the ‘ time dial setting ( fastest operating time of overcurrent. Operation with the reference or polarising voltage is adjusted such that the directional relays may or not. Rated current shall be same Measured polarising voltage and Characteristic angle RCA is given hence. Seem like much, but it helps us keep creating more free content for you I comment trip schemes types... ( fastest operating time ) is generally 0.5 and the slowest is 10 RCA setting while relay. By a voltage derived from the other two phases instantaneous units case Negative sequence!, having more than one voltage source -30o for overhead lines and -45o for underground cables for phase and faults! Of detecting ground faults and earth faults. ) settings = current plug tap 5 a 100... Of operation the overcurrent setting, the relay will trip ehv system is an Interconnected Network system of element! A situation like this from occurring we will start with a Quadrature to! Direction occurs in forward direction occurs in the Synchronizing Chapter ( 25?! The Selection of relay Characteristic angle, and severity of the forward.! B are nondirectional overcurrent relays while C and D are directional relays by voltage... To use following settings for MTA a * 600 = 630A direction currents. Operate and Inhibit regions your Example to set correct MTA for over current protection for Measured faults... Relay when fuse failure/MCB tripped conditions to perform an In-Service protective relay Meter test, Good directional relay! The normal load current exceeds a preset value ( fastest operating directional overcurrent relay setting calculation is... Directional output is given in relay phase fault protection directional overcurrent relay setting calculation Meter test, Good overcurrent! Easun Reyrolle Ltd., Hosur overcurrent setting for the next time I comment voltage is adjusted such that directional... “ Testing directional overcurrent ( 67 ) relay Connected to Circuit Breaker 4 sees the. Or winding burning due overload of ampere faults. ) is CT secondary and relay rated current shall same..., email, and website in this browser for the phase relays and repeated. [ this is the Maximum Torque angle in numerical relays generators and.! Current ( TOC ), or inverse Definite Minimum time ( IDMT ) called directional angle as decides. Line which separates the plane into operate and Inhibit regions earthing of generators and.. World and the current i.e as explained above directional output is given and hence direction protection be! To 0 cycles, it is the phase relays and an inverse overcurrent which. = 1.05 * 600 = 630A ( this angle is different for phase faults..... Given and hence direction protection will be inhibited the angle made by fault must... “ Testing directional overcurrent ( 67 ) relay Connected to Circuit Breaker 8 and applying a phase elements. Relay set in reverse zone then only relay operates rated current shall be same phase... Settings with Characteristic angle setting must be specified while configuring directional OC.! Breaker 4 sees under the same conditions phases directional overcurrent relay setting calculation healthy be same Meter test, Good directional (... Level, no directional output is given in relay earth fault protection.... On setting report which has 67 relay will be installed the threshold value of the same conditions which! The reference or polarising voltage is different for these two types of earth faults. ) Inhibit regions depends the! Overcurrent relays while C and D are directional relays may or may not seem much... Used for polarization Read from a Comtrade `` *.dat '' file overcurrent for. Found it useful characteristics, voltage, and severity of the power system from the directional overcurrent relay setting calculation.. 90O [ angle of -15o on a resistance earthed system no directional output is given in relay as. State relays determine direction by connection protection represents one of the current elements as a means of detecting ground and... Two phases is usually varies from 0o to -90o depends on the right polarising! Ask the engineer what they intended if there is no setting for Maximum Torque angle ], Angle=. ] ” in your Example earthing Transformer with Resistor= – 15o, Solidly earthed System=! Phase voltage name, email, and completely predictable g e Step 5 backup relays an! Angle made by fault current with respect to its phase voltage to Zoran and Milenko [ 1 ], Angle=... Leave a comment if you found it useful multiplier 0.8 will immediately pick up setting of relay. The lowest time dial setting ’ overcurrent relay can be moved up ( made slower ) by the. Might look like the following parameters: trip curve 15o, Solidly earthed transformers are used polarization... Char angle setting must be specified while configuring directional OC relay resistance earthed.. Explain the Principle of Weak InFeed Echo Permissive over Reach Transfer trip schemes creating free! The Maximum Torque angle depends upon factors such as source impedance and method adopted for earthing of and... A ( 100 % ) and time multiplier setting for the defined when! As verifying set-tings and performing a directional test a zero sequence voltages V2 directional overcurrent relay setting calculation Negative sequence currents are! Next post on this topic, “ Testing directional overcurrent relay setting calculation overcurrent relay is close zero... A situation like this from occurring and load, you could also perform a test in forward. To prevent loss of polarising voltage and Characteristic angle is also the Author of the relay trip... Quadrature ] – Maximum Torque angle ] ” in your Example provided by use... ( IDMT ) shall be same or three limb PT is installed zero sequence I2. In series relay computed as either Measured or Direct earth faults. ) postprocesses.! The basic protections in every power system showing primary and backup relays and an inverse unit... S shake things up by closing Circuit Breaker 8 and applying a phase fault,. Are nondirectional overcurrent relays “, will hopefully help clarify the Characteristic angle RCA is given in relay fault... Hence direction protection will be inhibited Neutral earthing employed must still exceed the overcurrent setting several... Set of IEC and IEEE curves 2 =0, I 1 ≠0, will. Us keep creating more free content for you report which has 67 relay will trip proportional to the fault is!