0. If not, … Directional relay is used when graded time overload protection is applied to ring mains and interconnected networks. Multiple Choice Question (MCQ) of Protective Relays page-4; Multiple Choice Question (MCQ) of Protective Relays page-3; Multiple Choice Question (MCQ) of Protective Relays page-2; Multiple Choice Question (MCQ) of Protective Relays page-1; Multiple Choice Question (MCQ) of Fuse; Multiple Choice Question (MCQ) of Circuit Breaker page-3 The output of the relay is a normally-open contact, which changes over to closed state when the relay trips. A. What are the functions of protective relays? 1. Inverse Time Over-current Relay. Interview Questions; Frame Relay; 6. In an IDMT (inverse definite minimum time) relay, the operating principle is based on the idea that with the more severe a fault is, the faster it should be cleared to avoid damage to the apparatus. See a list of common communication skills interview questions. Why distance protection is preferred as primary protection compared to overcurrent protection for transmission lines? I interviewed at Relay Therapeutics in February 2020. For what type of fault does Buchholz relay is employed? A. The time setting decides the operating time of the relay while the plug setting decides the current required for the relay to pick up. A relay must get an adequate chance to protect the zone under its primary protection. c. Tripping circuit. Where does Negative phase sequence relay is employed? It has two contacts namely fixed contact & moving contact. Contacted for a phone interview followed by a skype interview with a number of team members. Define IDMT relay? What does the first part consist of? DLCIs have local significance. What Is The Operation Principle Of Differential Relay? A. Only if the primary protection does not clear the fault, the back-up protection should initiate tripping. Can we measure over voltage and over current by measuring current only? We have to allow for the overshoot of the primary relay, so that there is proper coordination between the primary and the back-up. Question2: Difference between Switched Virtual Circuits (SVCs) and Permanent Virtual Circuits (PVCs)? Here are some very important current transformer interview questions with proper answers which are mostly asked with Electrical Graduates in every industrial interview as … A CT whose primary is in series with the line in which current is to be measured. Dear Readers, Welcome to Switchgear Protection Interview Questions and Answers have been designed specially to get you acquainted with the nature of questions you may encounter during your Job interview for the subject of Switchgear Protection.These Switchgear Protection Questions are very important for campus placement test and … Protection Relays Interview Questions & Answers Where does the Negative phase sequence relay is employed? What is the committed information rate (CIR)? Normal, Alert, Emergency, In extremis and Restorative. Here’s how to answer the 16 most common interview questions: Browse from thousands of Electrical questions and answers (Q&A). To detect the fault and initiate the operation of the circuit breaker to isolate the defective element from the rest of the system, thereby protecting the system from damages consequent to the fault. Accept Read More, Protection Relays Interview Questions & Answers. Question 2. Thus as soon as the fault takes place, it is sensed by both the primary and the back-up protection. As there is no counter m.m.f, primary m.m.f produces high flux in the core which leads to excessive core losses and overheating. The team was very welcoming and friendly. A. Shunt Faults: Basically shunt faults are short circuits. Many questions about teamwork will be behavioral interview questions. Windows Server Interview Questions: Windows Server is a series of different server operating systems that have been developed by the Microsoft Corporation. Biased differential relay is preferred because its operation is not affected by the trouble arising out of the difference in the CTs ratios for high values of external short circuit currents. These are the time setting and the plug setting. Name the different kinds of over current relays. The process took 2 weeks. Actually they used for isolating the CBs for maintenance. Question 5. Types: 1. If they got excellent grades, this will be easy to answer. Question4: What is a Data Link Connection Identifier (DLCI)? A differential relay operates when the phasor difference of two or more similar electrical quantities exceeds a pre-determined amount. b. current transformer interview questions and answers is very important for electrical graduates. These questions require you to provide an example from your past work experiences. So, they have very short arcing time and can interrupt high currents. The generation, distribution, and transmission system … Series Faults: Series faults are nothing but a break in the path of current. A PT primary is connected in parallel at the point where a measurement is desired. Under normal conditions the moving contact comes in contact with fixed contact thereby forming the closed contact for the flow of current. (adsbygoogle = window.adsbygoogle || []).push({}); A. Section 2: Electrical Interview Questions and Answers About Operating Principles and Relay Characteristics. Actuating quantity is change in current in case of over current relay Reverse Power flow relay are used to stop the flow of power from grid to station generator when the generating units are off. Electric Interview Questions In Relay . Post on: April 24, 2016 . What is reverse power relay? It is an electrical device designed to initiate the isolation of a part of the electrical installation, or to operate an alarm signal, in the event of abnormal condition or a fault. Interview. Negative sequence relay is employed for the protection of generators and motors against unbalanced loading that may arise due to phase to phase faults. Answer : Access Rate; Committed Information Rate; Voice Over Internet Protocol (VOIP) Interview Questions . Where Impedance relay, Reactance relay, and Mho relays are employed? We'll assume you're ok with this, but you can opt-out if you wish. Foundation Fieldbus Interview Questions and Answers, Electrical Cables Interview Questions & Answers, Transmission and Distribution Interview Questions, Electric Drives and Traction Interview Questions, High Voltage and Power System Stability Interview Questions, Power Electronics Interview Questions Part-1, Transformers Interview Questions & Answers, What is FAT and SAT? Negative sequence relay is employed for the protection of generators and motors against unbalanced loading that may arise due to phase to phase faults. The voltage transformer or potential transformer steps down the high voltage of the line to a level safe enough for the relaying system (pressure coil of relay) and personnel to handle. Thus fuses are used for only once but breakers can used by multiple number of times. Difference between them, Electrical & Instrumentation QC Interview Questions, Start Stop of one Motor from the same Push button PLC program, Remote Seal Transmitters Ranging Calculation, Difference between AC and DC Solenoid Valves, Ability to operate with low values of voltage, There should be no voltage and current creep. Explain the working of an Over current relay and mention the types of it? Did you also work with Electromechanical relays? A. In addition to job-specific interview questions, you will also be asked more general questions about your employment history, education, strengths, weaknesses, achievements, goals, and plans. Q. Vacuum Circuit Breaker 6. Question3: At what layers of the OSI model does Frame Relay operate? An over-current (OC) relay has a single input in the form of ac current. The operation of a relay should be fast and selective, ie, it should isolate the fault in the shortest possible time causing minimum disturbance to … What is protective relay? Whereas CB gets activated under fault conditions according to the fault detected. Explain The Encapsulation Types Of Frame Relay? Oil Circuit Breaker 3. The Impedance relay is suitable for the phase faults relaying for the lines of moderate lengths Reactance type relays are employed for the ground faults while Mho type of relays is best suited for the long transmission lines and particularly where synchronizing power surge may occur. This website uses cookies to improve your experience. A. It is an inverse definite minimum time relay. Generator Protection Interview Questions; Protection Relays Interview Questions; Neutral Grounding in Power System; Answer: Basic fundamental elements of the relay are: Sensing element: It is the measuring element measures the actuating quantity. 23. Networking Tutorial. d. All of these. A. Fuses are burnt when over current flows in the circuit but circuit breakers will just open during over current. The CIR is the committed information rate, by the service provider, in bits per second, at which data will be transferred. In IDMT relay its operating is inversely proportional and also a characteristic of minimum time after which this relay operates. During abnormal & faulty conditions (when current exceeds the rated value) an arc is produced between the fixed & moving contacts & thereby it forms the open circuit arc is extinguished by the Arc Quenching media like air, oil, vacuum etc. Related: 20 Customer Service Tips Why biased differential protection is preferred over simple differential protection? No real technical question but they asked me to submit a piece of code that I had written. While there’s no way to know for sure what topics will be covered, there are several popular interview questions you can expect to be asked. 300+ TOP Protection Relay Engineer Interview Questions [UPDATED] Question 1. A. Think of DLCIs as the MAC address of the Frame Relay network. The relay has two settings. Some of the reasons are faster protection, simpler coordination, simpler application, permanent settings without the need for readjustment, less effect of the amount of generation and fault levels, fault current magnitude, permits the high line loading. a. A. IDMT relays have better fault clearing times over DTOC relays. 78% of relaying is still electromechanical. 22. A. A. Answer : In this article, we share some of the most commonly asked interview questions with tips on what interviewers are looking for in your response and example answers. What is the need of relay coordination? When voltage increases then current also increases then what is the need of over voltage relay and over current relay? It is inverse in the sense, the tripping time will decrease as the magnitude of fault current increase. We can set the pick-up value of the relay, keeping in mind that the relay should allow normal load as well as a certain degree of overload to be supplied. Soft skills interview questions aim to reveal how strong a candidate's soft skills are before a hiring decision is made. The relay has two settings. Behavioral Interview Questions. Save my name, email, and website in this browser for the next time I comment. The current transformer has two jobs to do. Here are some important Windows Server Interview Questions for fresher and experienced candidate both. I don't leave many remarks, but i did some searching and wound up here "Interview Questions on Transformer Protection". A. But, DTOC relays are used for lines which are short in length as Zs>>Zl and If remains almost same. Bharadwaj. What grades did you get in college? In the above figure, the relay circuit is divided into three parts. What are soft skills interview questions? Question 6. Best Switchgear Protection Interview Questions and Answers. Refer to the diagram below to answer Question 5 to Question 8 Q5. How definite time lag is achieved in attraction armature relays? When the path of the load current is cut short because of breakdown of insulation, we say that a ‘short circuit’ has occurred which is nothing but a shunt fault. The farthest point from the relay location, which is still inside the zone of protection, is called the reach point. With an additional 53 professionally written interview answer examples. Protection Relays Interview Questions & Answers . It is a differential relay where the operating current required to trip can be expressed as a percentage of load current. Firstly, it steps down the current to such a level that it can be easily handled by the relay current coil. A. Review this list of 15 questions and answers to help you prepare for your next interview. Global Relay interview details: 159 interview questions and 108 interview reviews posted anonymously by Global Relay interview candidates. What is the operation principle of the differential relay? Secondary of the CT and the operating coil. Learn Windows Server Interview Questions and answer cracks the interview. What Are The Bandwidth Specifications Of Frame Relay? These are the time setting and the plug setting. Buchholz relay provides protection only against transformer internal fault. Thus, the pick-up value should be less than the smallest fault current. Where does the Negative phase sequence relay is employed? Relay interview details: 1 interview questions and 1 interview reviews posted anonymously by Relay interview candidates. Induction type non-directional over current relay,Induction type directional over current relay & current differential relay. A. Distance relay is superior to overcurrent protection for the protection of transmission lines. A. Air Blast Circuit Breaker 5. Practice 27 Global Relay Communications, Inc. Interview Questions with professional interview answer examples with advice on how to answer each question. Differential Relays must have the following features: Relay settings mean the actual value of the energizing or characteristic quantity at which the relay is designed to operate under given conditions. The circuit breaker is an electrically operated switch, which is capable of safely making, as well as breaking, short-circuit currents. It is observed in practice that most of the open conductor faults sooner or later develop into some or the other short-circuit fault. Naturally the primary protection is the first to operate, it’s operating time being less than that of the back-up relay. For example, an interviewer might ask, “Tell me about a time you … What is the percentage differential relay? If the secondary of a CT is open current through it is zero and hence the ampere turns produced by secondary which generally oppose the primary ampere turns becomes zero. Instantaneous Over-current Relay 2. What Is The Operation Principle Of Differential Relay? Primary winding of a current CT which is connected in series with the line to be protected. Become a part of our community of millions and ask any question that you do not find in our Electrical Q&A library. Q. Define operating time of … Negative sequence relay is employed for the protection of generators and motors against unbalanced loading that may arise due to phase to phase faults. EelectricalLive.com | 2015-2020 | Contact US, Interview Question On Circuit Breaker And Relay, Torque-Slip Characteristics In Three Phase Induction Motor. Of ac current Question 8 Q5 for example, an interviewer might ask, Tell... A library, etc over-current ( OC ) relay has a single input in the above,... Naturally the primary relay, Reactance relay, Reactance relay, and website in this browser the. 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