1. This project on Primary sub station of Visakhapatnam port trust at Visakhapatnam. It is 132kv/11kv substation with incoming feeder from APTransco and 11 outgoing feeders which supplies power to various units in the port. In this substation the incoming feeder from APtransco gives power at 132kv and this steps down to a voltage of 11kv with the help of transformer rating. The secondary of this transformer connected to a busbar to which the 11 feeders at 11kv are connected. In this project about the distribution of power using circuit breakers and relays.In this sf6 circuit breaker is using because of it has more advantages compare to other circuit breaker.Buchholz relay is used to protect the transformers against slow raising faults.

2. INTRODUCTION OF SUB STATION The present Day electric power is generated transmitted & distributed in the form of A.C It may desirable &necessary to change some characteristic of electric suuply which accomplish by suitable apparatus called substation

5. SWITCH YARD The term switchgear, used in association with the electric power system, or grid, refers to the combination of electrical disconnects, fuses and/or circuit breaker used to isolate electrical equipment. Basic Component Of Switch Yard: 1. Isolator. 2. Current x-mer. 3. Potential x-mer. 4. Circuit breaker. 5. Lightning arrester.

6. ISOLATOR These are used to disconnection transmission line under no-load condition for safety, isolation and maintenance.

7. CURRENT TRANSFORMER These are used to step-down currents for measurement, control & protection.

8. POTENTIAL TRANFORMER These are used to step-down voltage for measurement.

9. CIRCUIT BREAKER CIRCUIT BREAKER IS NOTHING BUT A SWITCH USED TO OPEN OR CLOSE THE CIRCUIT UNDER LOADING CONDITIONS. VACUUM CIRCUIT BREAKER IS EMPLOYED IN THIS POWER PLANT. WHEN EVER THE RELAY SENSES THE FAULT & GIVE SIGNAL TO THE CIRCUIT BREAKER IT OPENS OR CLOSES THE CIRCUIT.

10. LIGHTNING ARRESTOR LIGHTNING ARRESTORS ARE ALSO CALLED SURGE DIVERTERS USED TO PROTECT THE EQUIPMENT IN SWITCH-YARD. THESE ARE USED TO GROUND THE SURGE CURRENTS WHEN EVER THE LIGHTENING OCCURS. THE VALVE TYPE LIGHTNING ARRESTORS ARE U SED IN PLANT.

11. EARTHING The purpose of earthing system is to in a power station area is to limit the potential gradient within and immediately outside the area. Mainly the Earthing is of 2 types Pipe Earthing Plate Earthing Pipe Earthing Plate Earthing

12. CONCLUSION From the project on substation about switch gear, it is very necessary to protect every substation. Switch yard plays a major role in protection of substation. The periodic maintenance should be done to every equipment in switchyard for better operation. In this substation the distribution is of radial type which is more advantageous when compared with the other type of distribution system. Butchholtz relay is more useful to protect the transformers from slow rising faults.SF6 and Air break circuit breakers are efficient to protect substation.