seminar_power substation equipments.pptx

power substation equipments

1. Power Substation Equipments Submitted By: ODISHA UNIVERSITY OF TECHNOLOGY AND RESEARCH Submitted To: Sourav Satapathy Regd. No. : 23110157 Prof. Aswini Kumar Das

2. TABLE OF CONTENTS Introduction Transmission Electrical Sub-Station Lighting Arrested Instrument Transformer Isolator and Earth Switch Circuit Breaker Power Transformer Conclusion

3. INTRODUCTION Power stations: Produce electricity from combustible fuels (coal, natural gas, biomass) or non-combustible fuels (wind, solar, nuclear, hydro). Transmission lines: Carry electricity from power plants to demand centers. Transformers: Reduce voltage so distribution lines can deliver power for final use. This picture is from GOOGLE The electrical system consists of three main sectors:

4. After electricity is produced, it is transmitted across the country through a transmission line system. Power grids interconnect utilities, allowing power exchange to balance demand and prevent blackouts. Two types of electric power transmission: Overhead line design goals: Maintain safe clearance, ensure reliability against storms, ice, earthquakes, etc.; can operate above 765 kV between conductors. Interconnected transmission lines form the National Grid, with connections made at Grid Sub-Stations. Overhead transmission Underground transmission TRANSMISSION

5. ELECTRICAL SUB-STATION The assembly of apparatus used to change some characteristics (e.g. Voltage AC to DC frequency, Power factor, etc) of electric supply is called sub-station. TYPES OF SUB-STATION Transmission substation Distribution substation Collector substation Converter substation Switching substation Classification by Insulation substation Classification by Structure substation

6. ELECTRICAL SUB-STATION COMPONENT Primary power lines 1. overhead lines 3. Disconnect switch 5. Current transformer 7. Ground wire 2. Transformer for measurement 4. Circuit breaker 6. Lighting arrester 8. This picture is from GOOGLE

7. LIGHTING ARRESTER ( ) Lightning arresters protect substation equipment by discharging lightning and switching surges to earth; they consist of spark gaps and non-linear resistances (e.g., thyrite, metrosil). They allow heavy surge currents (thousands of amperes), dissipate energy quickly, then return to high resistance to stop arc continuation. Rated voltage: 80% of max line-to-line voltage for solidly earthed systems; 100% for unearthed systems (as arrester faces full line voltage during faults). Lighting Arrester Surge Counter This picture is from GOOGLE This picture is from GOOGLE

8. INSTRUMENT TRANSFORMER Purpose: Step down high voltage/current to safe levels for metering & protection; isolate secondary circuits from high voltages. Main types: CT designs: Window, bushing, bar, wound; insulation types – dead tank & live tank. Applications: Metering (accurate range 5–120%), protection (maintains accuracy under fault currents). Current Transformer (CT): Connected in series; converts high current to standard low current. Potential/Voltage Transformer (PT or VT): Connected in parallel; converts high voltage to standard low voltage.

9. CURRENT TRANSFORMER ( ) POTENTIAL TRANSFORMER ( ) Connected in series with the power line. Steps down high current to a standard low current (e.g., 5A) for metering/protection. Secondary must never be open-circuited for safety. Connected in parallel across the power line. Steps down high voltage to a standard low voltage (e.g., 110V) for meters/relays. Secondary is fused and must not be short-circuited. This picture is from GOOGLE This picture is from GOOGLE

10. Purpose: Disconnect a section/unit of a substation under no-load; always operated after opening and before closing the circuit breaker. Placement: Usually installed on both sides of circuit breakers for maintenance and safety. ISOLATOR & EARTH SWITCH ( ) Line Isolator 1. Bus Isolator 2. Transformer Isolator 3. This picture is from GOOGLE This video is from YOUTUBE

11. CIRCUIT BREAKER A protective device that automatically interrupts abnormal/fault currents (short-circuit or overload) to protect the system. Operates manually or automatically and can safely make or break circuits. SF₆ Circuit Breaker 1. 2. Vacuum Circuit Breaker

12. SF₆ CIRCUIT BREAKER ( ) VACUUM CIRCUIT BREAKER ( ) Uses Sulphur hexafluoride gas for arc extinction and insulation. Suitable for high-voltage applications; provides excellent insulation, fast operation, and low maintenance. Uses a vacuum as the arc-quenching medium; arc extinguishes quickly in vacuum. Commonly used in medium-voltage systems; long service life and low maintenance. This picture is from GOOGLE This picture is from GOOGLE

13. POWER TRANSFORMER Works on electromagnetism (current produces magnetic field) and electromagnetic induction (changing magnetic flux induces voltage). Primary and secondary circuits are electrically isolated but magnetically linked via a low-reluctance path. AC in primary induces AC voltage in secondary; used to transfer voltage from one side to another. Station transformers observed: 33/11 kV, D–Y mode, rated 5 kVA, used for night supply/emergency power, all properly grounded. TRANSFORMER BASICS Shapes: Core type or Shell type, laminated silicon steel core to reduce losses. Laminations stepped for circular cross-section; secured with bolts and nuts. Tank materials: sheet steel (small) or boiler plate (large), with thermometer pockets & radiator tubes for cooling. Windings: 3-phase has 6 windings (3 primary + 3 secondary), made of enamelled copper with insulation and insulating paper layers. CONSTRUCTION & CORE

14. Tank filled and sealed with mineral oil (refined petroleum). Functions: Oil level and quality should be checked regularly. TRANSFORMER OIL Provides additional insulation. Cools core and windings. Must have high dielectric strength, low viscosity, be acid-free, and resist sludge formation This picture is from GOOGLE POWER TRANSFORMER

15. Air-tight drum mounted above tank, connected to it; partially filled with oil. Accommodates oil expansion/contraction due to temperature changes, preventing contact with air. CONSERVATOR Maintains oil insulation by preventing moisture ingress. Contains silica gel crystals to absorb moisture from incoming air when oil contracts. BREATHER This picture is from GOOGLE POWER TRANSFORMER

16. Provides insulated connection to external circuits. Up to 33 kV: porcelain bushings; above 33 kV: oil-filled bushings (hollow porcelain filled with oil). BUSHING Adjusts transformer output voltage. 132/33 kV: uses on-load tap changer (OLTC). 33/11 kV: uses off-load tap changer (manual). Tap changing done on HV side (lower current, less arcing). TAP CHANGER This picture is from GOOGLE POWER TRANSFORMER

17. CONCLUSION The seminar provided a comprehensive understanding of the electrical power system and its components, including generation, transmission, distribution, and substation equipment. Special focus was given to transformers, their working principles, construction, and essential accessories like oil, conservator, breather, bushings, and tap changers. Proper design, maintenance, and protection devices such as lightning arresters and circuit breakers are crucial for reliable and safe operation of substations. Overall, an efficient electrical system ensures uninterrupted power supply and safety during both normal and emergency conditions.

18. THANK YOU FOR LISTENING I appreciate your interest and hope this presentation has provided valuable insights.

19. Q & A