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- 1. COURSE CODE :18EE72 POWERSYSTEM PROTECTION (Core Subject) Faculty : SRIDHAR N H Assistant professor
- 2. Module-1 Introduction toPower System Protection: Need for protective schemes Nature and Cause of Faults Types of Faults, Effects of Faults Fault Statistics, Zones of Protection Primary and Backup Protection Essential Qualities of Protection Performance of Protective Relaying Classification of Protective Relays Automatic Reclosing CTs-VTs for protection
- 3. Cont….., Relay Constructionand Operating Principles: Electromechanical Relays, Static Relays – Merits and Demerits of Static Relays, Numerical Relays, Comparison between Electromechanical Relays and Numerical Relays. Overcurrent Protection: Introduction, Time – current Characteristics, Current Setting,
- 4. Objective of powersystem protection To isolate a fault section of electrical power system from the rest of the live system so that rest portion can function satisfactorily without any severer damage due to fault current.
- 5. What Components(Equipment) Do We Protect? •Generators •Transformers •Lines •Buses •Capacitors
- 6. Protective system elements Fuses Circuit breakers Relays CTs &PTs
- 7. An electrical powersystem consists of generators, transformers, transmission and distribution lines, etc. Short circuits and other abnormal conditions often occur on a power system. The heavy current associated with short circuits is likely to cause damage to equipment if suitable protective relays and circuit breakers are not provided for the protection of each section of the power system. Short circuits are usually called faults by power engineers. Strictly speaking, the term fault simply means a defect. Some defects, other than short circuits, are also termed as faults. For example, the failure of conducting path due to a break in a conductor is a type of fault. NEED FOR PROTECTIVE SCHEMES
- 10. Effects of faults Heavy short circuit current may damage to equipment or any other element due to over heating and high mechanical force set up due to heavy current. Area associated with short circuit may cause fire hazards. There may be reduction in the supply voltage of the healthy feeders, resulting in the loss of industrial loads. Short circuit may cause the unbalancing of supply voltages and currents ,thereby heating rotating machines. There may be loss of system stability. Loss of revenue.
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- 15. There are threetypes of back-up protection Remote backup Relay backup Breaker backup
- 17. Performance of protectiverelay Correct operation Incorrect operation No conclusion
- 19. BASED ON SPEEDOF OPERATION Instantaneous Relay Time Delay Relay High Speed Relay Ultra High Speed Relay
- 20. Over Current Protection DistanceProtection Carrier Current Protection Differential Protection classification of protective schemes
- 24. Relay Construction andOperating Principles
- 25. Electromechanical Relays Arelay is an electromechanical device having electrical, magnetic and mechanical components. The relays control the electric circuit by opening or closing the contacts of that circuit. An electromechanical relay consists of three terminals namely common (COM), normally closed (NC) and normally opened (NO) contacts. These can either get opened or closed when the relay is in operation. These relays can work on both AC and DC supply sources.
- 27. 1. HINGED ARMATURETYPE 2. PLUNGER TYPE 3. BALANCED BEAM TYPE 4.MOVING COIL TYPE 5. POLARISED MOVING IRON TYPE 6.REED TYPE ATTRACTED ARMATURE RELAYS
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