power system protection and why to protect the system
- 1. CONTENT INTRODUCTION ELEMENTS OF PROTECTION SYSTEM ELECTRICAL SYSTEM FAULT AND SYSTEM PROTECTION WITH PROTECTIVE RELAYS CONCLUSION Power System Protection
- 2. WHY A SYSTEM NEEDS PROTECTION ? 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 over current, over voltage, lighting, etc.
- 3. ELEMENT OF PROTECTION SYSTEM (1)Current and Voltage Transformers (2)Relays (3)Circuit breakers (4)Batteries (5) Fuses (6)Lighting Arresters
- 4. CURRENT TRANSFORMER Current transformer consists at least of two secondary windings. The first winding is usually designed for measuring, the second is used for protection. The secondary of current transformers are almost connected in star
- 5. VOLTAGE TRANSFORMER Voltage transformer is often consists of two windings. The first winding is connected in star, and the stare point must be earthed. The second winding is connected as open delta.
- 6. RELAY PURPOSE Isolate controlling circuit from controlled circuit. Control high voltage system with low voltage. Control high current system with low current.
- 7. ADVANTAGES FOR USING PROTECTIVE RELAYS Detect system failures when they occur and isolate the faulted section from the remaining of the system. Mitigating the effects of failures after they occur. Minimize risk of fire, danger to personal and other high voltage systems.
- 8. CIRCUIT BREAKER Low voltage circuit breaker Magnetic circuit breaker Medium voltage circuit breaker High voltage circuit breaker
- 9. BATTERY BANK Battery bank are called as backbone of protection system Emergency use for power system
- 10. FUSE Fuses are selected to allow passage of normal current and of excessive current only for short periods. It is used to protect the low voltage or current rating devices
- 11. LIGHTING ARRESTER A lightning arrester is a device used on electrical power system to protect the insulation damaging effect of lightning. All lighting arrester are earthed
- 13. PROTECTIVE DEVICES COMPARISON CIRCUIT BREAKER V/S RELAY Relays are like human brain; circuit breakers are like human muscle. Relays 'make decisions' based on settings. Relays send signals to circuit breakers. Based the sending signals circuit breakers will open/close.
- 14. GENERATOR PROTECTION Generator Differential Protection Loss of Field or Loss of Excitation Protection Negative Sequence or Current Unbalance Protection Over Fluxing or Over Excitation Protection Over Current Protection Stator Earth Fault Protection
- 15. Rotor Earth Fault Protection Restricted Earth Fault Protection Backup Impedance Protection Low Forward Power Protection Reverse Power Protection Over Frequency Protection Under Frequency Protection Over Voltage Protection
- 16. GENERATOR PROTECTION Differential Protection: Detects faults within the generator's stator windings by comparing the current entering and leaving the generator. Rotor Earth Fault Protection: Protects the rotor winding from faults to ground, potentially preventing severe mechanical damage. Inter-turn Fault Protection: Detects faults between turns of the stator windings, preventing phase-to-phase and phase-to-earth faults. Loss of Excitation Protection: Protects the power system from instability if the generator loses its field excitation.
- 17. GENERATOR PROTECTION DIFFERENTIAL AND GROUND FAULT
- 18. NEGATIVE SEQUENCE The direction of rotation of a negative sequence is opposite to what is obtained when the positive sequence are applied. Negative Sequence Relay will constantly measure and compare the magnitude and direction of the current.
- 19. TRANSFORMER PROTECTION Gas and Temperature Monitoring Thermal protection Differential and Ground Fault Protection Over current protection
- 22. TRANSFORMER PROTECTION GROUND FAULT AND DIFFERENTIAL RELAY
- 23. THERMAL OVERLOAD RELAYS Use bimetallic strips to open/close relay contacts when temperature exceeds/drops to certain level. Require certain reaction time Inverse time/current relationship
- 24. TRANSMISSION LINE PROTECTION Distance protection Earth fault protection Over current protection Carrier protection
- 25. CONCLUSION Relays control output circuits of a much higher power. Safety is increased Protective relays are essential for keeping faults in the system isolated and keep equipment from being damaged. Relay is like an insurance against damage due to fault.
- 26. THANK YOU NAME = KASIF ALI (21EEAEE014)