Differential relay 87

See also: relay. This relay is not sensitive for single line to earth faults as the earth fault current is limited due to the high neutral earthing resistance. Custom Transformers. Bus Differential and Breaker Failure Relay. Use the independent overcurrent elements to complement the high-impedance differential elements. Beyond Typical Transformer Protection— Protect reactors, generators, large motors, and other multiterminal power apparatus. Line differential protection. We first modeled the CTs and the relay algorithms to obtain the CT requirements and setting guidance for the relay (Fig. The SEL-487B provides optimized, low-impedance bus differential fault detection by using high-speed, subcycle protection coupled with high-security operation for external faults. 21 : Distance relay . I. – Takes advantage of existing relays on the protected bus. of rated load typically 150%. Interlocking/blocking schemes. This volume is designed to help you: Understand the basic characteristics of differential protection. – Would require directional relays applied to both the tie breaker Dec 22, 2022 · Here, two differential relays control the tripping of circuit breakers (ANSI/IEEE function 52) at each end of the transmission line. Hasil analisis dari simulasi tersebut akan digunakan sebagai referensi untuk menentukan setting differential relay transformeryang tepat, sehingga Apr 3, 2020 · Lock-Out Relay, Master Trip Relay: 87: Relay bảo vệ so lệch: Differential Protective Relay: 87B: Rơle bảo vệ so lệch thanh cái: Bus Differential: 87G: Rơle bảo vệ so lệch máy phát: Generator Differential: 87GT: Relay bảo vệ so lệch máy phát / máy biến áp: Generator/Transformer Differential: 87L: Rơle bảo Transformer Differential Protection Scheme works by using two separate quantities calculated from the primary current (IW1C) and secondary current (IW2C). This relay device follows the ANSI standard 87L – line differential. Using a relay with both ATB and KCL elements provides organizational benefits. Now consider a transformer differential characteristic for a two-winding transformer connected delta (DAB) – wye with wye connected CTs on both sides. e phase relays, ground fault relays, differential relay, etc. Over Current Relay (50/51, 50/51G) 2. 6. 7-1, Issue C. •High-impedance differential (87Z) is desirable for many reasons •It requires matched ratio CTs Often, this is a limitation The “Busbar differential protection” function detects busbar short circuits. All motors 750 kVA and above on ungrounded systems. Low impedance percent These features permit the DP-300 to be universal in its applications. The differential protection of the SEL-387L uses the same measuring principle and communication as the fully configured SEL-311L Line Current Differential System. Review the application and ensure that it has been applied correctly Apr 18, 2007 · Errata to the Type 87M Instruction Booklet IB 7. A short-circuit bypasses the differential protection element, so that the equipment is unprotected. 7a) [5]. Fault Outside the Protection Area. Standard Feature. 86 Lock-Out Relay Electrically operated hand, or electrically reset relay or device that functions to shut down or hold equipment out of service upon the occurrence of abnormal conditions. 1. Apply IR of 5 amperes and adjust the operat-ing current until the relay operates. 7-1 REV:- 5a schneider micom p543 line differential protection relay; Alstom ge micom agile p543,p544,p545 & p546 line differentia Abb make ret615 transformer differential protection relay; Overload relay siemens reyrolle-7sr54-transformer differenti Siemens din rail 7rw80 voltage frequency protection relay, 2 Oct 25, 2021 · Differential Relay Operationhttps://youtu. This relay will be used as the reference for one of the CTs while the PD-DCT-SEC feeder breaker will be used as the other reference CT. 3 External faultsWhen faults arise outside the CTs, the differential circuit of the relay may be supplied with a relatively large current, which can be caused by ratio errors in the CTs, or by the tap-changer not being in the center-tap posi- tion. หลักการทำงาน ของ Diff. Superior protection performance is combined with integrated station automation features for seamless transition into new Mar 4, 2024 · It is important to choose “the proper tool for the proper job”. Retrieved from https://ijeeas. Location CO Figure 3-2 Tripping logic of the differential element of SEL. SIPROTEC 7UT82, SIPROTEC 7UT85, SIPROTEC 7UT86 and SIPROTEC 7UT87. Apply IR of 60 amperes and adjust the oper-ating current until the relay operates. Two-winding dual-slope differential protection with harmonic blocking and restraint, and phase, negative-sequence, residual Principles of Differential Relaying Setting a low z diff relay Point 2, I. 25 ± 0. 1MRK 504 002-UEN. Generator differential protection (87 G) It is unit type protection, covering the stator winding for phase to phase faults due to breakdown of insulation between stator phase windings. A simple form of differential current protection for this generator may be implemented by connecting CTs on either side of Use the through-fault event monitor in the SEL-387-5 and SEL-387-6 for information on system through faults and the resulting, cumulative I2t wear on trans-former banks. 243. relay, backup 51NT AC time neutral overcurrent relay, torque controlled 52 AC circuit breaker 59 Overvoltage relay 60 Voltage or current balance relay 63 Pressure switch or relay 67 AC directional overcurrent relay 67G AC directional overcurrent relay, neutral 86 Lockout relay 87 Differential relay 87G Ground differential relay . The SEL-311L is set to transmit a data bit to put the SEL-387L into “follower” mode. The SEL-787Z relay is a flexible high-impedance differential relay designed primarily for high-impedance bus protec-tion. Applied with inrush and overexcitation restraints. To better understand the issue, the authors of this paper contacted the authors [13]. It also contains zero-sequence and negative-sequence differential protections. 0. IEEE Guide for Application of Digital Line Current Differential Relays Using Digital Communication. The SIPROTEC 7UT82/85/86/87 transformer differential protection have been designed specifically for the protection of two and multi-winding (up to 5 sides). SIPROTEC 7UT613 (phase-out product) The SIPROTEC 7UT613 differential protection relays are used for fast and selective fault clearing of short-circuits in transformers of all voltage levels and also in rotating electric machines like motors and generators, for short lines and busbars. A numerical transformer differential relay internally compensates the CT currents as follows: Winding 1 (DAB) Winding 2 (Wye) I A1relay A= 1 TAP1 I [09] I A2relay = 2 3 2 •-AP I A I B [12] I The relay also supports high-impedance grounded, ungrounded, and Petersen coil-grounded systems in relays with the 200 mA neutral current transformer option. The reactor presents a high impedance (over 1000 ohms) to the flow of operate current. Altuve, Schweitzer Engineering Laboratories, Inc. Page 4. D32 Working Group. Secure the 87L element operation with external fault detection (EFD) and disturbance detection logic. Protection Relay-Based Electrical Signature Analysis for Advanced Motor Condition Monitoring Watch this webinar to learn how to successfully set up Electrical Signature Analysis (ESA) in the Multilin 859 & 869 motor protection relays. Metode penelitian pada Tugas Akhir ini menggunakan software ETAP 12. Fig. This model implements a transformer differential relay (87T) with harmonic restraint and harmonic blocking functions. Model Option. 7- 7 Page 9 Theseconservative calculationscan be refined to produce lowersettings if thefollowing or other practical conditionsare considered: Maximumfault current isusually lower than interrupting ratings. Hasil analisis dari simulasi tersebut akan digunakan sebagai referensi untuk menentukan setting differential relay transformer yang tepat, sehingga sistem proteksi differential relay (87T) dapat bekerja dengan cepat dan selektif dalam mengatasi gangguan. Self-Monitoring and Relay Maintenance A new trend of extending maintenance intervals based on the amount of self-monitoring in microprocessor-based relays Version 1. 87 Differential Protective Relay Functions on a percentage or phase angle or other quantitative difference of two currents or of some other electrical Phase Differential. The SEL-787L combines line current differential protection and directional and non-directional overcurrent protection. transformer differential relay under the simulated transients are presented and discussed in this paper. This applies to tripping from the differential, as well as backup functions. - Relay oscillograph analysis software can be used determine the inrush current level and fine tune the setting. High impedance differential. Major Features and Benefits. Letters can be added to clarify application (87T for transformer differential, 59G for ground overvoltage). An open CT circuit generates a differential current that is measured by the EBR-3000. Os relés diferenciais de corrente normalmente são equipados com enrolamentos de restrição aos quais as entradas de TC devem ser conectadas. Michael J. SEL787 and SEL 387/587 Transformer differential relay is used for this discussion. This instruction manual provides information about the operation and installation of the BE1-87G Variable Percentage Differential relay. Differential Relay (87) Overcurrent Relay (50/51) การทํางานของ O/C คือ Relay จะให Output เมื่อมีกระแสเข าตัว Relay เกินค า Setting แบ งเป น 2 ชนิดคือ 1. Rơleso lệch dòng thường được trang bị cuộn dây nối với đầu vào Metode penelitian pada Tugas Akhir ini menggunakan software ETAP 12. International Journal of Electrical Engineering and Applied Sciences (IJEEAS), 3(1). Differential Relay (87) หลักการทางานของ Diff. I have mostly seen differential relays used for substation transformer protection; connected between the high side and the low side. PJV Instantaneous Voltage Relay 27, 59 PVD Differential Voltage Relay 87 RRTD Remote RTD Module 30,49, 74(+) SAM Static Timing Relay 2 SB-1 Control and Transfer Switches 30, 74 SB-10 Control and Transfer Switches 30, 74 SB-9 Master Control Switches 30, 74 SBC Static Breaker Backup Relays 50BF SBD Differential Voltage Relay 87 relays is performed using a simulation of the power system near an approximately 1700 MVA Type 4 wind farm and a , simulation of the relay a lgorithm [1 3]. Dual-slope percentage, harmonic restraint and blocking, plus Abstract—Testing line current differential (87L) schemes is more complicated than testing directional comparison schemes. Nov 18, 2019 · Directional-overcurrent relay . INTRODUCTION Line current differential (87L) protection is applied on long and short lines and on various voltage levels. Make use of simple settings and dedicated same-ratio CTs to dilakukan analisis setting differential relay transformer (87T) dengan pertimbangan vector grouppada PLTU Tenayan 2x110 MW. H. It comprises up to three CT inputs (assuming there can be 3 transformer windings). A sudden pressure relay is also applied to protect the transformer. Explore your application to see where our custom SEL-587-0, -1 Current Differential Relay; APP 87: SEL-387 and SEL-587 Percentage-Restrained Differential Relays Learn More. APP 87 provides comprehensive application training for the SEL-387 and the SEL‑587 percentage-restrained differential relays, which offer sensitive, high-speed protection for transformer, machine, and bus differential applications. The latter exchange simple on/off (permission or block) signals that can be conveniently checked at the output of a given relay and conveniently forced at the input to a given relay in the scheme. Adding a KCL element provides extra sensitivity and speed. Training TST 103: SEL Feeder Relay Testing 1. • Disadvantages: – The scheme gets really complex especially when you consider the affects of a single relay outage. The 200 mA CT option can also be used for nondirectional sensitive earth fault (SEF) protection. Take advantage of automation features that include 16 elements for each. Line current differential relays operate on a difference in current into the line compared to the current out of the line. The only variation is how this is implemented. Transformer differential protection protects against short-circuits between turns of a winding and between windings that correspond to phase-to-phase or three-phase type short-circuits. The status quo is: The 11kV network is only protected by 50/51G and 27 relay (between CT3 and CT4). be/9sc9WsiqmA4Differential Relay Testinghttps://youtu. - Also, need to know if the high set element uses Question: Assume that transformer differential relays ( 87T ) are connected as shown on the one-line diagram below. This provides the capability to use the two relays together. Dual-Slope Percentage Bias Differential Relay (87) Protection Strategy for 11kV Underground Power Cable. – The probability of a failure with the scheme is greater than a single relay application. A 27/59 device, for example, is a combination under/over voltage relay. The relays shall be tuned to fundamental frequency to reject harmonics produced by ABB Circuit Shield Type 87M Percent Machine Differential Relay. E. Motor overcurrent differential relay (Device 87) Motor overcurrent differential protection measures the current flow into a load and compares it to the current measured on the neutral side of the motor. Paper includes more applications. Although nowadays differential protection is achieved numerically, in order to understand the principles of differential protection it is useful to analyze the ubiquitous electromechanical relay. Class “C” CT; 10% at 20X rated. Issue C page 4, 3rdparagraph, 7thsentence. Đối với thiết bị này cần bảo vệ chống chạm đất để tránh hư hỏng thiết bị. Transformer differential protection. On a 20 MVA base, an internal three-phase fault at F,determin: [1] The total reactance to the fault [2] Fault current [3] Max load current [4] The coil Jan 24, 2024 · Thanks for the answers. Jun 7, 2018 · Complex Two-Terminal Application. Feb 26, 2007 · Feb 28, 2007. Applied with variable percentage slopes to accommodate CT saturation and CT ratio errors. Issue C page 4, 3rdparagraph, 7thsentence clarification The reactor presents a high impedance to the flow of operate current. Commonly, differential protection is used for large (>2000HP) medium voltage motors or large motors that are very critical or expensive. Instantaneous O/C Relay (50) Transformer differential protection. Automation. Then, we spot-checked the guidance by executing hardware-in-the-loop tests with The SEL-587Z Relay uses internal 2000-ohm resistors to provide security against the effects of CT saturation for through faults. Carrier or pilot wire receive relay: 86: Tripping Relay: 87: Differential relay: 87G: Generator differential relay: 87G: T Overall differential relay: 87U: UAT differential relay: 87NT: Restricted earth fault relay: 95: Trip circuit supervision relay: 99: Over flux relay: 186A: Auto reclose lockout relay: 186B: Auto reclose lockout relay Nov 8, 2012 · The Relay Testing Handbook: Testing Differential Protection (87) provides step-by-step procedures for testing the most common differential protection applications. TP2. The SEL-587 Current Differential Relay combines overcurrent and differential elements in an easy-to-apply power apparatus differential protection package. Standard Protection Features. Relay security is achieved by an optimized set of user-select-able restraining and blocking elements. 1 Core Balance Type. Introduction to ANSI code 87 T. Supports a direct serial fiber, IEEE C37. They are suited for use in utility-, industrial-, and commercial-scale power For the high-impedance differential protection scheme, it is important to have CTs and the secondary bus wiring in a proper condition. loading could be anything from 100% to 200%. 81R - common industry use for Rate Of Change Of Frequency Relay (ROCOF) 81U - Under Frequency; 82 - DC Reclosing Relay; 83 - Automatic Selective Control or Transfer Relay; 84 - Operating Mechanism; 85 - Pilot Communications, Carrier or Pilot-Wire Relay; 86 - Lock-Out Relay, Master Trip Relay; 87 - Differential Protective Relay; 87B - Bus Rule of thumb: If the motor kVA rating is less than half the transformer, use overcurrent (50) in lieu of differential (87). ID: 7. To provide this feature, the percentage-type differential relay, Device 87, illustrated at right of figure 5-8 (a), has been developed; 이러한 Mar 22, 2012 · Multifunction relays have combinations of device numbers. The greatest troublesome cause of current transformer saturation is the transient dc component of the short circuit current. Para eletromecânica 87 diferencial de correnterelés, a corrente através dos enrolamentos de restrição para cada fase é somada e a soma é direcionada através de um enrolamento de operação. Other similar relays use similar concepts through the actual terminology could be different. 012 amperes. the relay to open the circuit breaker to isolate fault. utem Apr 4, 2022 · Case Study: Motor Protection Relay Retrofit and Upgrade. Thread starter MrJLH; Start date Jul 17, 2020; Status Not open for further replies. 1. The DP-300 permits design simplification of the switchgear cabi-net, facilitates the commissioning, ensures the operation of the system, is user friendly, and increases the availability of the sys-tem. two or more input electrical quantities exceeds a predefined value. In the system under study, the equipment, protected by the differential relay (87), is a 125 MVA, 500/115 kV three-phase transformer connecting a 500 kV transmission grid to a 115 kV sub-transmission network. The combined SIPROTEC 7SL87 line differential and distance protection has specifically been designed for the protection of lines Mar 5, 2024 · 1. Feb 24, 2012 · Generally both of the switches are in “IN’ position in normal operating condition. 6. Select the XFM-Relay device in the Captor TCC drawing (Figure 4) and click the Function button to display the Protection Functions. The BDD differential relays should be used for all applica- - Type BDD differential relay 8686 87-1 87-2 87-3 Similar to phase 1 52-1 52-1 52-2 52-2 52-3 52-3 52-4 May 25, 2019 · Differential protection for universal use with power lines and cables on all voltage levels with phase-segregated measurement (87L). Figure 1 shows a simple differential protection scheme, also known as a Merz-Price scheme. SIPROTEC 7SD82, SIPROTEC 7SD86 and SIPROTEC 7SD87. (corresponding to twice rated load) suffices. Each circuit breaker in zone A is connected with individual contact of 96A. 0. For most cases a turning point of 2. , Muhammad Nizam Kamarudin, Lee Qui Fang, Ahmad Sadhiqin Mohd Isira, & Mohamed Fauzi Packeer Mohamed. a) What faults will a transformer differential relay scheme detect that would not be detected by the sudden pressure relay?b) What faults or conditions will a sudden pressure relay be purpose of testing the differential, we used conservative guidance and assumed that one CT saturates to a degree whereas the other does not. Voltage Regulators DECS-150 Digital Excitation Control System The DECS-150 features entire system solutions and total control in one compact package providing precise voltage, var and power factor regulation, and exceptional system response, plus generator protection. With capabilities through 2,800 kVA, Basler has the ability to meet most dry type transformer needs. Single pole tripping is possible with phase-segregated measurement. ”. 96A relay is multi contacts relay. The SEL-787 Transformer Protection Relay is a versatile, two-winding current differential relay that protects industrial transformers. transformers. Bus protection products and systems provide complete primary and backup protection for all types of bus and switchgear arrangements. The relay should operate and the indicator lamp should light with an operating current of 0. IEEE Standard 242 – Buff Book. M. Click the New button and type in Differential under the Function Name The SEL-387A Current Differential and Overcurrent Relay is a low-cost solution for two-winding transformer protection. Jun 1, 2019 · This is where differential protection excels because the relay can be set very sensitively to capture low level faults in the motor. The SEL-787 Transformer Protection Relay provides unsurpassed protection, integration, and control features in a flexible, compact, and cost-effective package. Monitor critical operating temperatures through use of the SEL-2600A RTD module. Various existing implementations: Unrestrained differential. Mar 16, 2023 · Description. A current difference is detected as a fault. If unit is LTC, add another 10%. A differential relay operates when the difference between. The SIPROTEC 7SD82/86/87 line differential protection have been designed particularly for the selective protection of overhead lines and cables with single-ended and multi-ended infeed in medium-voltage and high-voltage systems. Repeat for each phase of the relay. To accomplish this, the following information is provided: General Information and Specifications Controls and Indicators Functional Description Installation Testing and Setting. #5. 1 Differential protection function (ANSI 87) The differential protection function (ANSI 87) is based on the principle of comparison of electric currents, founded on Oct 10, 2017 · High-Impedance Differential Applications With Mismatched CTs Russ Franklin, Alliant Energy Hossein Nabi-Bidhendi, ABB Inc. Jan 8, 2010 · A modern line current differential relay should be capable of single-pole tripping and reclosing. 2Differential protection of power transformers and the common disturbances 2. 5. For more detailed information on “Busbar differential protection” function, refer to Dec 9, 2016 · Differential protection. 52 Relay DC Supply Communications Oct 1, 2018 · To prevent this malfunction of current differential busbar protection, the 87 relays are provided with high pick up current and enough time delay. The relay device has 3 bundle inputs for local current transformers (CTs) and 3 bundle inputs for communication with remote relay devices. Allocation of setting parameter on relay’s operating graph [4] VII. Set with at least a 15% pick up to accommodate CT performance. MrJLH Senior Member. Relay คือ ตรวจสอบความแตกต่าง (Different) ของกระแสที่ไหลเข้าและออกจากอุปกรณ์ที่ Relay ป้องกันอยู่ ถ้าแตกต่าง Feb 24, 2012 · Differential protection is typically employed for electrical power transformers rated above 5MVA. Protective Relaying System . 87 : Differential relay . Provide backup distribution bus or feeder protection with low-side overcurrent elements. 52 : Circuit breaker . Annual Conference for Protective Relay Engineers, A&M University 04/05/2017. Students (in groups of two) gain hands-on experience in communicating, setting, metering, monitoring, retrieving and analyzing event reports, and performing Apr 24, 2021 · Differential voltage relays also exist, with the same “87” ANSI/IEEE designation, making it necessary to specify whether the differential quantity in question is voltage or current whenever mentioning an “87” relay. On a side note, the 87 is part of an ANSI list of industry standard numbers to identify diffferent types of protection, i. 물론 이 differential 계전기의 경우 protection 구간 이외의 고장 조건에서 흐르는 가장 큰 차전류 또는 오류 전류로 인해서는 작동해선 절대 안된다. The initial phase of configuring the settings for the differential protection relay involves gathering data, and to accomplish this, we have opted to use a 100 MVA Power Transformer. Fault Inside the Protection Area. Differential protection offers several advantages compared to other transformer protection schemes. Internally mounted metal-oxide varistors (MOVs) are connected in parallel with the high-impedance element to clamp secondary peak voltage to less than 2 kV. Feb 11, 2012 · Generator differential protection (87/G1): the protection is provided with high speed, high stability circulating current relays. Our custom transformers are designed to application-specific electrical, mechanical, thermal, and regulatory requirements using cost-effective materials and processes. The relay is also suitable for restricted earth fault (REF) applications on transformers with grounded-wye windings. Relay คือ ตรวจสอบความแตกต่าง (Different) ของกระแสที่ไหลเข้าและออกจากอุปกรณ์ที่ Relay ป้องกันอยู่ ถ้าแตกต่างกันน้อยไม่เกินค่า Setting ก็จะ Jul 23, 2020 · 87 - Bus Differential Relay Trip Settings. The principles of differential INTRODUCTION. ‡ 1/2/3 Relay Application. (2020). High-Impedance Differential Relays IB 7. It is stable in the event of external short-circuits with current-transformer saturation through intelligent saturation-detection methods, and is used for the single busbar. Here, relay coil of 96A and 96B are in series with differential busbar protection relay contact 87A-1 and 87B-1 respectively. SIPROTEC 4 7UT6 Differential Protection Relay for Transformers – Connection of transformer differential protection with high SIPROTEC 7SL87 is a combined phase-selective line differential and distance protection for overhead lines and cables with single-ended and multi-ended infeed of all lengths with up to 6 line ends and 1-pole tripping. Thompson and Héctor J. 1 September 1997. The 87 differential relays are connected to the generator neutral and circuit breaker CTs. • High impedance & percentage differential relay (87) • Phase, ground, & directional overcurrent relay (51/50, 67) • Detailed implementation of voltage restraint & control relay (51V) • Comprehensive modeling of electronic & hydraulic reclosers (79) • Overload relay - CT based & Inline relays (49) • Comprehensive relay interlocks Rơ le so lệch dòng. Using ATB for everything may lead to compromises in performance. ƒ This function may be created using settings. The current at each end of the line is monitored by current transformers connected to local 87 relays, which makes the differential current protection zone cover the entire length of the transmission line. For smaller transformers allowable maximum. . be/h6jaTVGfqA4 Aug 17, 2022 · 1. I'll give the diagram here: So, I want to add 87T between CT2 and CT6 so the 11 kV line will be protected by 87T. Faced with an aging fleet of motor protection relays, the client, a city's water management department, began upgrading to the modern Multilin 869 motor management relay May 1, 2021 · Single-line diagram of the study system is illustrated in Fig. Result and discussion The tripping response of the differential relay is observed after setting is inserted by reinjecting 4 types of All bus zone protections essentially operate based on Kirchoff’s law for currents: “The sum of all currents entering a node must equal zero. Monitor transformer health with cumulative through-fault current recording, and for the first time in the industry, automatically check and generate differential compensation settings with the Commissioning Assistant Software. Turning. The selected transformer corresponds to the real transformer installed in the field, and the settings are computed specifically for the GE P642 Differential Apr 1, 2017 · Summary Paper for C37. While the Buchholz relay can detect faults occurring within the transformer’s insulating oil, it fails to detect faults that do not involve the oil. The relays has a pick up range of 10 to 40% of 5A and shall have suitable stabilizing for ensuring stability against external faults. Differential Protection Setting Calculations 87H Pickup - Typically set at 8 to 12 pu rated current - This value should be set to above the maximum possible inrush current. by: Neftaly Torres, P. Modelling of dual slope percentage bias differential relay in PSCAD Fig. (IA/ICTL/IAC) [60] field relay (power system device function numbers) A relay that functions on a given or abnormally low value or failure of machine field current, or on an excessive value the relay using test mode, multiple-relay tests of the characteristics and channel using test mode, and multiple-relay tests of the characteristics and channel without test mode where real-world conditions are simulated. of The simulated event from [13] is played back through relay hardware to observe the event record of Bus Protection Features. 70. 2. All motors 750 kVA and above on grounded systems where ground fault protection won’t detect phase-phase faults. Rơ le so lệch dòng thường được sử dụngđể bảo vệmáy biến áplớn, máy phát điện và động cơ. There are three styles of motor differential protection. Faulted circuit CT'sofstandarddesign neversaturate completely. D27 Working Group. 4 Flags available in the tripping function and the output bundle of the relay 87_Pk: Differential current detected on phase k, K=A, B, C INH_k_2ND: 2nd harmonic detection and inhibition for phase k, k= A, B or C INH_2ND: 2nd harmonic detection and inhibition in one of the 3 phases A relay that functions to prevent overheating of the field excitation winding by reducing or interrupting the excitation of the shunt field. 94-compatible communication interface with a range of as far as 25 km. th. Apr 30, 2020 · Hairi, M. tg fk dd oy jz bc yn fx du ih