Electric substation

working of electrical sub station ,types of sub station

1. ELECTRIC SUBSTATION SUBMITTED TO: GAGANDEEP SINGH WALLIA SUBMITTED BY: ANNU KUMAR REGISTRATION NO: 11711796 ROLL NO: B43 SECTION :1708 CASE STUDY

2. TABLE OF CONTANT INTRODUCTION TRANSFORMER CONDUCTORS , INSULATORS ISOLATORS BUSBARS LIGHTNING ARRESTERS CIRCUIT BREAKERS CONCLUSION REFERENCES

3. INTRODUCTION ELECRIC SUBSTATION : Part of an electrical, generation , transmission ,distribution system . Here voltage gets transforms from low to high or high to low(generally). Between generation to consumption various sub station may involve, at various level May be public or private owned May be of several types of substations ; transmission, pole, switching , distribution e.t.c .

4. This case study is based on TRANSMISSION SUBSTATION so important components used here are as follows, ELECTRICAL POWER TRANSFORMERS INSTRUMENTS TRANSFORMERS CONDUCTORS INSULATORS ISOLATORS BUS BARS LIGHTNING ARRESTERS CIRCUIT BREAKERS ELECTRICAL PANELS

5. SINGLE LINE CIRCUIT DIAGRAM

6. ELECTRICAL POWER TRANSFORMERS A STATIC ELECTRICAL MACHINE USED TO TRANSFORMS LOW VOLTAGE TO HIGH OR VICE VERSA. WORKING PRINCIPLE BASED ON FARADAY LAW OF ELECTROMAGNETIC INDUCTION ( a varying current in one coil produces varying magnetic field which in turn induces voltage in other coil)

7. FOUR COMBINATION IS POSSIBLE DEPENDING UPON USE AND LEVEL OF TRANSMISSION

8. INSTRUMENT TRANSFORMERS CURRENT TRANSFORMERS VOLTAGE TRANSFORMERS Instrument transformers scale the large values of voltage or current to small, standardized values that are easy to handle for instruments and protective relays . . This is because measuring meters or instruments and protective relays are low voltage devices , thereby cannot be connected directly to high voltage circuit for the purpose of measurement and protection of the system . A current transformer provides a secondary current that is accurately proportional to the current flowing in its primary. The current transformer presents a negligible load to the primary circuit. Current transformers are the current sensing units of the power system.  

9. CONDUCTORS The material that allows the flow of electric charge is called conductor. Conductors permit free movement of the flow of electrons through them . These are used for the transmission of power or electrical energy. Conductors are of different types and mostly aluminum conductors are preferred in practical power systems . Al 61% of conductivity than Cu. But has 30 % weight of copper. Bare wire of Al weighs half of Cu of same resistance.

10. Types of Conductors: AAC - All Aluminum Conductor. AAAC - All Aluminum Alloy Conductor. ACSR - Aluminum Conductor Steel Reinforced. ACAR - Aluminum Conductor Aluminum-Alloy Reinforced

11. INSULATORS An  electrical insulator  is a material whose internal electric charges  do not flow freely Insulators used for high-voltage power transmission are made from glass, porcelain or composite polymer materials. Strain insulator Suspension insulator

12. ISOLATORS Isolator switch  is used to ensure that an electrical circuit is completely de-energized for service or maintenance. The disconnector is usually not intended for normal control of the circuit, but only for safety isolation. Disconnectors can be operated either manually or automatically. Disconnectors lack a mechanism for suppression of electric arcs. They are off-load devices. Disconnectors have provisions for a  lockout- tagout so that inadvertent operation is not possible.

13. LIGHTNING ARRESTER A  lightning arrester  is a device used on electrical power systems to protect the insulation and conductors of the system from the damaging effects of lightning. If protection fails or is absent, lightning that strikes the electrical system introduces thousands of kilovolts that may damage the transmission lines, and can also cause severe damage to transformers and other electrical or electronic devices. USED BOTH SIDE OF TRANSFORMER These prevent the flow of the normal power or signal currents to ground, but provide a path over which high-voltage  lightning  current flows bypasses to earth. connected parallel to device to be protected

14. BUSBARS A busbar   is a metallic strip or bar, typically housed inside switchgear,  panel boards, and busway enclosures for local high current power distribution . They are also used to connect high voltage equipment at electrical switchyards, and low voltage equipment in battery banks . They are generally uninsulated, and have sufficient stiffness to be supported in air by insulated pillars . These features allow sufficient cooling of the conductors, and the ability to tap in at various points without creating a new joint . It can be used outside

15. CIRCUIT BREAKERS Vacuum interrupter  is a  switch which uses electrical contacts  in a vacuum. It is the core component of medium-voltage switches. Separation of the electrical contacts results in a vacuum arc, which is quickly extinguished. The separation of contacts causes the release of vapour which is filled in the contact space. It consists positive ions liberated from contact material. The vapour density depends on the current in the arc. When the current decreases, the rate of vapour release decreases and after current zero. M edium regain its dielectric strength if the vapour density is reduced.

16. CONCLUSION VARIOUS ELECTRICTAL SYSTAMS ARE WONDERFULLY CONTRIBUTING TO TRANSMISSION AND DISTRIBUTION SYSTEMS KNOWING THE SAFETY PRECAUTION TAKEN DURING WORKING MAINTAINING THE HEALTH OF EQUIPMENT IS VERY NECESSARY

17. REFERENCES WIKIPEDIA www.elprocus.com/vacuum-circuit-breaker-working-applications www.edgefx.in/electrical-engineering-substation-components-and-their-workings EE NPTEL PDF IIT KHARAGPUR WWW.QUORA.COM GOOGLE IMAGE