STUDY OF SUBSTATION COMPONENTS

UNDER THE GUIDENCE OF

Mr. PAVAN KUMR

BALA KRISHNA

SUBSTATION COMPONENTS

A substation is a part of an electrical generation, transmission,

and distribution system.

Between the generating station and consumer, electric power may flow

through several substations at different voltage levels.

Transmission substation

Distribution substation

Converter substations

Switching substation

Classification by insulation

Classification by structure

CLASSIFICATION

MAIN COMPONENTS

TRANSFORMER

CIRCUIT BREAKER

LIGHTING ARRESTERCURRENT TRANSFORMER

BUS BAR ISOLATOR

POTENTIAL TRANSFORMER WAVE TRAP

INSULATOR EARTH SWITCH

EARTHING SYSTEMCONTROL PANEL

CABLES CABLE PARTS

TYPES OF CABLESTWISTED CABLES

TRANSFORMER

• Power transformers are used in transmission network of higher voltages for step-

up and step down application (400 kV, 200 kV, 110 kV, 66 kV, 33kV) and are

generally rated above 200MVA.

• Distribution transformers are used for lower voltage distribution networks as a

means to end user connectivity. (11kV, 6.6 kV, 3.3 kV, 440V, 230V) and are

generally rated less than 200 MVA.

PARTS OF TRANSFORMER

Main tankPrimary winding Secondary winding Buchholz relay Oil level indicator BreatherRadiatorL T & HT bushesTap changer Air release plug

Buchholz relaysBuchholz relays are used in most oil insulated electric transformers where there is an expansion tank. Buchholz relays are particularly efficient in detecting and capturing gases that may form inside the transformers and for instant system shut down in case of a serious defect.

CONSERVATOR

The conservator provides space

for the expansion of oil .

CONSERVATOR

BUCHHOLZ RELAY

BREATHER

The breather filled with silica gels

are provided to separate moisture from

the aspirated air.

The silica gel turns blue when it

becomes saturated with moisture

after which it needs to be replaced.

AIR RELEASE PLUGS These air releasing plugs are made

from very excellent quality raw material which ensure hassle free work performance. These plugs finds its applications in various industrial sectors. We are able to customized these plugs as per customer requirement with market competitive rates

BREATHER

AIR RELEASE PLUGS

TERMINAL BOX

A terminal box is designed to enable the electrical connection of the elements within a transformer to the external elements in an airtight and reliable manner that ensures

years of trouble-free operation.

COOLING FANS

They are used for cooling of

the transformer when there is a temperature raise in the transformer.

TERMINAL BOX

COOLING FANS

RADIATORS The radiator of transformer accelerates the cooling rate of transformer. Thus, it plays a vital role in increasing loading capacity of an electrical transformer. This is basic function of radiator of an electrical power.

TRANSFORMER RATING

RADIATORS

TAP CHANGER A tap changer is a connection point selection mechanism along a power T/F winding that allows a variable number of turns to be selected in discrete steps. A T/F with a variable turns ratio is produced, enabling stepped voltage regulation of the output. The tap selection may be made via an automatic or manual tap .

BHUSHINGS OF T/FThe oil impregnated paper insulated bushings arc used to connect over head lines to T/F. These are mounted on t/f in vertical or inclined position at a maximum inclnation of 30° from the verticaL.

TAP CHANGER

BUSHINGS OF T/F

BUS BARS

• a bus bar is a thick strip of copper or aluminium that conducts electricity.

• Bus bars are used to carry very large currents, or to distribute current to

multiple devices within switchgear or equipment.

CIRCUIT BREAKER

•It designed to protect an electrical

circuit from damage caused by

overload or short circuit.

•Its basic function is to detect a fault

condition and discontinue the

electric flow

.

BULK OIL CB

BULK OIL CB

It uses a large quantity of oilThe oil serves two purposes.Firstly ,it extinguishes the arc during opening of contacts.Secondly ,it insulates the current conduting parts from one anthor and from the earthed tank.

AIR BLAST CBThe CB in which high pressure air blast is used for extinguishing the arc.The arcing products are completely removed by the blast whereas the oil deteriorates with successive operations.The expense of regular oil replacement is avoided

AIR BLAST

MINIMUM OIL CB•These types of circuit breakers utilize oil

as the interrupting media. However,

unlike bulk oil circuit breaker, a minimum

oil circuit breaker places the interrupting

unit in insulating chamber at live potential.

• The insulating oil is available only in

interrupting chamber. The features of

designing MOCB is to reduce requirement

of oil, and hence these breaker are

called minimum oil circuit breaker.

CROSS BLAST CBThe CB in which the air blast is directed right angles to the arc path.

The splitters serve to increase the arc

length of the arc and baffles give improved

cooling resulting in extinguished arc.

MINIMUM OIL

CROSS BLAST

AUXIAL BLAST CBThe circuit breaker in which

the air blast is directed long

the arc path

When the fault occurs the arc

is extinguished and current

flow is interrupted.

SF6 CBThe circuit breaker in which

sulphur dioxide (SF6)gas is

used for arc extinction.

Due to superior arc quenching

property of SF6 ,such circuit

breakers have short arcing

time.

AUXIAL BLAST

SF 6

1. Actuator lever - used to manually

trip and reset the circuit breaker.

2. Actuator mechanism - forces the

contacts together or apart

3. Contacts - Allow current when

touching and break the current when

moved apart

4. Terminals

5. Bimetallic strip.

6. Calibration screw - allows the

manufacturer to precisely adjust the

trip current of the device after

assembly.

7. Solenoid

8. Arc divider/extinguisher

CIRCUIT BREAKER

ISOLATOR

•It is a disconnection

switch and to be operated

on no load.

•It is used to make sure

that an electrical circuit can

be completely de-energized

for service or maintenance.

• It provide electrical isolation of the equipment .

CURRENT TRANSFORMER

•CT is a type of instrument transformer

that is used in power system for

measurement, detection, protection of the

system.

•Current transformers are used extensively

for measuring current and monitoring the operation of the power grid.

POTENTIAL TRANSFORMER

Potential transformers are instrument

transformers. They have a large number of

primary turns and a few number of

secondary turns.

It converts voltages from high to low. It

will take the thousands of volts behind

power transmission systems and step the

voltage down to something that meters can

handle.

LIGHTING ARRESTER

It discharge the over voltage surges to earth

and protect the equipment insulation from

switching surges and lightning surges.

It located at the starting of the substation as

seen from incoming transmission lines and is the first equipment of the substation

INSULATOR

An insulator, also called a dielectric,

is a material that resists the flow of

electric current.

Insulators are used in electrical

equipment to support and separate

electrical conductors without allowing

current through themselves.

PIN TYPE

SUSPENSION TYPE

PIN TYPEPin type insulators are used for transmission and distribution of electric power at voltages up to 33 kV. Beyond operating voltage of 33 kV, the pin type insulators become too bulky and hence uneconomical.

SUSPENISION TYPEFor high voltages (>33 kV), we use suspension type insulators. Each unit or disc is designed for low voltage, say 11 kV. For instance, if the working voltage is 66 kV, then six discs in series will be provided on the string.

STRAIN TYPEWhen there is a dead end of the line or there is corner or sharp curve, the line is subjected to greater tension. In order to relieve the line of excessive tension, strain insulators are used. For low voltage lines (< 11 kV), shackle insulators are used as strain insulators.

STRAIN TYPE

STRAIN TYPE

SHACKLE TYPE

SHACKLE TYPEIn early days, the shackle insulators were used as strain insulators. But now a day, they are frequently used for low voltage distribution lines. Such insulators can be used either in a horizontal position or in a vertical position. They can be directly fixed to the pole with a bolt or to the cross arm.

STRAIN TYPEWhen there is a dead end of the line or there is corner or sharp curve, the line is subjected to greater tension. In order to relieve the line of excessive tension, strain insulators are used. For low voltage lines (< 11 kV), shackle insulators are used as strain insulators. However, for high voltage transmission lines, strain insulator consists of an assembly of suspension insulators as shown in Figure. The discs of strain insulators are used in the vertical plane. When the tension in lines is exceedingly high, at long river spans, two or more strings are used in parallel.

WAVE TRAP

It trap the high frequency communication

signals sent on the line from the remote

substation and diverting them to the telecom/

teleprotection panel in the substation control

room .

The Line trap offers high impedance to the

high frequency communication signals thus

obstructs the flow of these signals in to the

substation bus bars.

The signals are primarily teleprotection

signals and in addition, voice and data

communication signals.

EARTH SWITCH Earth Switch is used to discharge the voltage on the circuit to

the earth for safety.

Earth switch is mounted on the frame of the isolators.

Earth Switch is located for each incomer transmission line and

each side of the bus-bar section

EARTHING SYSTEM

Station Earthing System includes Earth Mat and Earth electrodes placed below ground levelFunction earthing system is to provide low resistance earthing for Discharging currents from the surge arresters, overhead shielding, earthing switches For equipment body earthing

For safe touch potential and step potential in substation.

METERING, CONTROL AND RELAY PANELS

To house various measuring Instruments, control Instruments, Protective relays.

They are located in air-conditioned building. Control Cables are laid between

Switchyard equipment and these panels.

RELAYS TYPESElectromagnetic relays•These are those relays which are operated by

electromagnetic action. Modern electrical

protection relays are mainly micro processor

based, but still electromagnetic relay holds its

place. It will take much longer time to be

replaced the all electromagnetic relays by micro

processor based static relays.

Induction relay•This relay in nothing but one version of

induction disc relay. Induction cup relay work in

same principle of induction disc relay. The basis

construction of this relay is just like four poles

or eight pole induction motor. The number of

poles in the protective relay depends upon the

number of winding to be accommodated.

CABLES STRUCTURE & CONSTRUCTION

THREE CORE CABLES TYPES