logging in or signing up Introduction to Protection aSGuest136636 Download Post to : URL : Related Presentations : Let's Connect Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Copy embed code: Embed: Flash iPad Dynamic Copy Does not support media & animations Automatically changes to Flash or non-Flash embed WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 2034 Category: Education License: All Rights Reserved Like it (0) Dislike it (0) Added: June 04, 2012 This Presentation is Public Favorites: 0 Presentation Description basics related to protection of power system Comments Posting comment... Premium member Presentation Transcript PowerPoint Presentation: INTRODUCTION TO POWER SYSTEM PROTECTION R&D Deptt. Protection & Control Division R.J.Phansalkar 1PowerPoint Presentation: What is Protected? Why protection is needed ? What is Power system & What are its basic elements ? Principle elements of Protection system including Circuit breakers, Relays, CTs & PTs Relay & Fuse comparison. What are Faults & why they occur ? Types of Relays & Digital relay Advantages & Enhancements Basic requirements of the Protection schemes Any Queries from the Audience Discussion Points 2PowerPoint Presentation: Protection of the equipments Protection of the personnel Protection of the property Protection of the protecting elements What is Protected ? 3PowerPoint Presentation: Power System includes: Generation System Electrical Power is obtained either by Thermal, Hydro, Nuclear, Solar, Wind Energy Transmission System Why transmission of Power? What are different voltages of power transmission? Overhead OR Underground? Distribution System All types of Electrical Loads Motors, Furnaces, Lights, Domestic appliances What is Power System ? 4PowerPoint Presentation: Power System Protection includes a series of devices, whose main purpose is to protect persons and primary electric power equipment from the effects of faults. Relays are like the “Sentinels” What is Protection System ? 5PowerPoint Presentation: There is no ‘ Fault Free ’ system. It is neither practical nor economical to build a ‘ Fault Free ’ System. Electrical system shall tolerate certain degree of faults. Usually faults are caused by breakdown of insulation due to various reasons: system aging, lighting etc. Why the system needs Protection ? 6PowerPoint Presentation: Cost of Damage because of Electrical Faults is directly proportional to the Square of the Fault current and is also directly proportional to the time for which Fault current flows. In addition to the direct losses there will be huge production losses if the fault is allowed to damage and power is not provided. SO PROTECTION OF THE POWER SYSTEM FROM THE FAULTS IS EXTREMELY IMPORTANT Why Protection ? 7PowerPoint Presentation: Damage to Main Equipment 8PowerPoint Presentation: http://video.google.com/videoplay?docid=7703052748770170847# Video showing severity of damage 9PowerPoint Presentation: I t I n I md Damage Curve Short-Circuit Current Damage Time Rated Value Electrical Equipment Thermal Damage 10PowerPoint Presentation: Whenever current flows in the unwanted device or unwanted place we call it a Fault Any undesired thing in the system such as Overvoltage or under voltage condition Or Over / Under frequency Condition we call it fault What is Fault? 11PowerPoint Presentation: Single-Phase-Ground : 70–80% Phase-Phase-Ground : 17–10% Phase-Phase : 10–8% Three-Phase : 3–2% Typical short circuit faults in the distribution system 12PowerPoint Presentation: Overload Insulation breakdown because of aging or over voltages External objects /Animals/Birds Mal operation of the Relays leading to system instability Rains/Moisture/Snow fall/ other external calamities WHAT ARE THE CAUSES OF FAULTS ? 13PowerPoint Presentation: Fuses Protective Relays Circuit Breakers Current & Voltage Transformers Communications Channels DC Supply System Control Cables Protection System Elements 14PowerPoint Presentation: Relays Circuit Breakers Fuses Acquisition Detection Activation Actuation Protective Devices Comparison 15PowerPoint Presentation: Relays are electrical switches that open or close another circuit under certain conditions. What are Relays ? 16PowerPoint Presentation: Isolate controlling circuit from controlled circuit. Control high voltage system with low voltage. Control high current system with low current. Logic Functions Relays Purpose 17PowerPoint Presentation: Electro-Mechanical Static Microprocessor based Microcontroller based Intelligent relays which can communicate with other devices Types of protective Relays ? 18PowerPoint Presentation: Electromagnetic Relays (EMRs) EMRs consist of an input coil that's wound to accept a particular voltage signal, plus a set of one or more contacts that rely on an armature (or lever) activated by the energized coil to open or close an electrical circuit. Solid-state Relays (SSRs) SSRs use semiconductor output instead of mechanical contacts to switch the circuit. The output device is optically-coupled to an LED light source inside the relay. The relay is turned on by energizing this LED, usually with low-voltage DC power. Microprocessor / Microcontroller based Relays Use microprocessor for switching mechanism. Commonly used in power system monitoring and protection. Relays Types 19PowerPoint Presentation: Fuses Vs. Relays Relays have different settings and can be set based on protection requirements. Relays can be reset. Fuses only have one specific characteristic for a individual type. Fuses cannot be reset but replaced if they blow. Protective Device Comparison 20PowerPoint Presentation: DC Tripping Circuit 21PowerPoint Presentation: Circuit Breaker 22PowerPoint Presentation: Very High Voltage CT Medium-Voltage CT Current Transformers 23PowerPoint Presentation: Medium Voltage High Voltage Note : Voltage transformers are also known as potential transformers Voltage Transformers 24PowerPoint Presentation: Protective Relays 25PowerPoint Presentation: What happens if protection fails ? What is Primary Protection ? Back-Up Protection Coordination Primary & Backup Protection 26PowerPoint Presentation: Primary Protection 27PowerPoint Presentation: Backup Protection 28PowerPoint Presentation: Single-Phase-Ground : 70–80% Phase-Phase-Ground : 17–10% Phase-Phase : 10–8% Three-Phase : 3–2% Typical Short circuit type Distribution 29PowerPoint Presentation: Why Faults occur 30PowerPoint Presentation: Protection Zone B Protection Zone A To Zone B Relays To Zone A Relays 52 Protection Zone B Protection Zone A To Zone B Relays To Zone A Relays 52 Primary Protection Zone Overlapping 31PowerPoint Presentation: When a fault takes place, the current, voltage, frequency, and other electrical variables behave in a peculiar way. For example: Current suddenly increases Voltage suddenly decreases Frequency suddenly drops Relays can measure the currents and the voltages and detect that there is an over-current , or an under voltage , or a combination of both Many other detection principles determine the design of protective relays How do Relays detects faults ? 32PowerPoint Presentation: Reliability Dependability Security Selectivity Speed System stability Equipment damage Power quality Sensitivity High-impedance faults Dispersed generation Main Protection requirements 33PowerPoint Presentation: Balanced System Unbalanced System Balanced Vs Unbalanced Conditions 34PowerPoint Presentation: Decomposition of an Unbalanced system 35PowerPoint Presentation: Over-current (50, 51, 50N, 51N) Directional Over-current (67, 67N) Distance (21, 21N) Differential (87) Power line protection principles 36PowerPoint Presentation: How a Relays Works ? 37PowerPoint Presentation: Solid State Relays 38PowerPoint Presentation: Multifunctional Compatibility with digital integrated systems Low maintenance (self-supervision) Highly sensitive, secure, and selective Adaptive Highly reliable (self-supervision) Reduced burden on CTs and VTs Programmable Versatile Low Cost Advantages of Digital Relays 39PowerPoint Presentation: THANKS 40 You do not have the permission to view this presentation. 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