AT 66K.V. SUBSTATION

ByPanjab university Elecrtical deppt

  I UNDERTOOK MY TRAINING AT 66K.V. SUB

STATION AT MANIMAJRA, WHICH COMES UNDER CHANDIGARH ELECTRICITY BOARD . IT IS A GOVERNMENT RUN BODY WHICH CONTROLS THE SUPPLY OF ELECTRICITY IN THE REGION OF UNION TERITORY OF CHANDIGARH AND ITS NEIGHBOURHOOD. IT ALSO MAINTIANS THE “ SCADA” RECORDS OF THE SAME REGION.

An electrical substation is a subsidiary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse using transformers.

Substations do not usually have generators

Transmission substation

Distribution substations

Collector substation

connects two or more transmission lines

The largest transmission substations can cover a large area (several acres/hectares) with multiple voltage levels, many circuit breakers and a large amount of protection and control equipment (voltage and current transformers, relays and SCADA systems).

transfers power from the transmission system to the distribution system of an area.

The input for a distribution substation is typically at least two transmission or subtransmission lines

Complicated distribution substations can be found in the downtown areas of large cities, with high-voltage switching, and switching and backup systems on the low-voltage side

Indoor type substations

Outdoor substations

in such substations the apparatus is installed within the substation building . such substations are usually for a voltage upto 11kv but can be erected for the 33kv and 66kv when the surrounding atmosphere is contaminated with impurities such as metal corroding gases and fumes etc.

they are of two types Pole mounted- they are erected for

distribution of power in localities. Single 4pole structures with suitable platforms are employed for transformers of capacity upto 25kva, 125kva and above.

Foundation mounted-for transformers of capacity above 250kva the transformers are too heavy for pole mounting . such substations are usually for voltages of 33000 volts and above

MAIN BUS BARS Switch gear Power transformer instrument transformers Protective relays Lighting arresters Batteries

An aluminum or copper conductor supported by insulators that interconnects the loads and the sources of electric power in an electric power system.

A typical application is the interconnection of the incoming and outgoing transmission lines and transformers at an electrical substation.

Bus-bars also interconnect the generator and the main transformers in a power plant.

Switchgear is used both to de-energize equipment to allow work to be done and to clear faults downstream.

Today, oil-filled equipment has largely been replaced by air-blast, vacuum, or SF6 equipment, allowing large currents and power levels to be safely controlled by automatic equipment incorporating digital controls, protection, metering and communications.

They are used for stepping up the voltage for transmission at generating stations and stepping down voltage for further distribution at main step down transformer substations.

Usually naturally cooled , oil immersed , known as on type, two winding , 3- phase transformers, are used upto the rating of 10mva

in electrical engineering, a current transformer (CT) is used for measurement of electric currents.

Current transformers, together with potential transformers (PT), are known as instrument transformers.

Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called "protection relays".

A relay is an electrically operated switch

It consists of a coil of wire surrounding a soft iron core, an iron yoke, which provides a low reluctance path for magnetic flux, a movable iron armature, and a set, or sets, of contacts; two in the relay pictured.

When an electric current is passed through the coil, the resulting magnetic field attracts the armature, and the consequent movement of the movable contact or contacts either makes or breaks a connection with a fixed contact

Buildings are protected from lightning by metallic lightning rods extending to the ground from a point above the highest part of the roof.

When lightning strikes it hits the rod and current flows down through the copper strip. These rods form a low-resistance path for the lightning discharge and prevent it from travelling through the structure itself.

In electric power stations and large capacity substations , the operating and automatic control circuits , the protective relay systems , as well as emergency lighting circuits are supplied by station batteries