Substation | Substation Definition & Types of Electrical substation or Power substation

Substation Definition & Types of Electrical substation or Power substation

An electrical substation or power substation are important for electricity. There are many types of power substation or electrical substation such as transformer substation, distribution substation, indoor substation, outdoor substation, Step up and step down substation, Electrical device substation, Transmission substation, switching substation, frequency changer substation, converting substation, industrial substation, power factor switching substation, Underground substation, converting substation, pole mounted substation, distribution substation, Primary & secondary grid substation.



The assembly of equipment to vary some characteristics of electrical power provide is named station. The current power system may be a.c. i.e. power is generated, transmitted, and distributed within the variety of the AC. the electrical power is made at a power station that area unit settled at favorable places usually quite far from the shoppers.


Classification of Substation

There are many types of substation

According to service requirement types of the substation is classified as:

  • Transformer Substation
  • Electrical device substation
  • Transmission substation
  • Switching Substation
  • Frequency changer Substations
  • Converting Substation
  • Industrial Substation
  • Power factor correction Substations

According to constructional feature, the types of the substation is classified as:

  • Indoor Substation
  • Outdoor Substation
  • Step up substation
  • Step down substation
  • Underground Substation
  • Primary grid substation
  • Secondary grid substation
  • Distribution substation
  • Pole mounted Substation

Transformer Substation

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It’s delivered to the shoppers through an oversized network of transmission and distribution. Transformer Substations are also in hand associate degree operated by an electrical utility or are also in hand by an oversized industrial or industrial client.

Electrical device station or Power transformer

electrical device They are called electrical device substations or power transformer as a result of the electrical device is the main element used to vary the voltage level, relying upon the purposed served electrical device substations.

A transmission station

What does a substation do? A transmission substation which convert the voltage level of electrical rations are named transformer this substation. These substations receive power at a voltage and deliver it at another voltage. Connects 2 or a lot of transmissions lines. The only case is wherever all transmission lines have identical voltage. In such cases, the station contains high-voltage switches that enable line to be connected or isolated for fault clearance or maintenance.

A transmission station might have transformers to convert between 2 transmission voltages, voltage control/power issue correction devices like capacitors, reactors

Switching Substation

Substation transformers also decrease the voltage higher to lower voltage, where it transforms 33 kV voltages to 11 kV voltages. After this transformation the 11kV is transmitted to the distribution part where within the transmission lines the distribution transformers occur to lower down the voltage (11 kV to 230 V). Those substations don’t turn the energy level incoming and outgoing channels have equal the energy.

Though they simply complete the switching methods of energy lines power factor correction substation.

Power Transformer is a device that converts inbound electricity to a better or lower value of voltage for specific purposes. it’s a serious component in grid to produce voltage in many nations. the 2 main functions of the transformers are:

  • To supply current from source to destination
  • To regulate the voltage of the present

It consists of a coil system within the device that manages the present flow within a particular range. Transformer generally employed in transmission network is generally referred to as power transformer. Basically, power transformer is employed in grid and substation.

Frequency Changer Substation

Those substations which change the frequency are referred to as changer substation, such a frequency change could also be rewired for industrial utilization.
An electrical grid is an interconnected network to produce electricity to consumers on a grid from the producer. Here 132 kV / 33 kV Step down power transformer is employed and transmitted to the substation parts. In Bangladesh most of this power transformers are of oil immerge type transformers. The capacity of grid transformer is sometimes 50/75 MVA.


Converting Substation

An electric substation for the conversion of electrical current—primarily with relation to frequency or the number of phases. It will be wont to convert a three-phase current of an advert frequency generated by an electrical station into an instantaneous current to feed, for instance, high-power electrolytic equipment, variable-speed electric drives for machine tools and rolling mills, galvanic baths, and phone systems of electrified transport. Conversion to an electrical energy of a frequency that’s higher or below the commercial frequency is employed for supplying power to such devices as variable-speed AC electric drives, warming equipment, and induction furnaces. Conversion to a single-phase electrical energy is finished to produce power to, for instance, high-capacity arc furnaces and single-phase contact systems. In DC power transmission lines, converter substations are accustomed convert a three-phase current to an immediate current (rectification) at the sending end of the road and to attain a reverse conversion (inversion) at the receiving end of the road. additionally, inversion is employed when a DC source, like a magneto hydrodynamic generator or a voltaic battery, must be connected to an AC distribution system.

Industrial Substation

How does a substation work? The Industrial Substation possibly a watertight design intended for close, dirty, and outside circumstances. The station consists of a sturdy watertight and dustproof casing (IP -65) of glowing aluminum metal. The first board is connected to the rear casing to authorize quick passage during foundation and improvement. The station has spiral extremities with numbers and also the three organs give the watertight and dustproof conjunction of lighting cable and amplifier wires. Those substations which provide energy to the different industrial company are called industrial substations.

Indoor substation

A station within which the equipment is provided within the station building is named indoor station.

Such form of station is especially used for the voltage up to 11000 v, however once the encircling air is contaminated by impurities like metal chemical action gases and

fumes, semi conductive dirt, etc., their voltage will be raised up to 33000 V to 66000 V.

Substations of the Integrity designed kind In such form of station, the device is provided on website. In such station, the cell structure is built of concrete or bricks.

Substations of the composite kind In such form of stations manufacturing plant or workshop area unit designed however area unit assembled on the website among a substation switch gear space.

The compartments of such substations take the shape of metal cupboards or enclosures, every of that contains the instrumentality of 1 main association cell.

In such cupboards, an associate degree oil breaker, a load device switch, and one or a lot of voltage transformers are also mounted.

Unit kind manufacturing plant made-up Substations and Metal Clad Switchboards These area units in-built electrical workshops and area unit carried to the positioning of installations totally pre-assembled.

once installations of substations and switchboards solely association to the incoming and outgoing power circuits area unit needed to be created.

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  •   Less area is needed
  •  Operation is less complicated than out of doors station Disadvantage
  •  Future extension is tough
  •   Capital price is high

 More risk of step-up Outdoor station for voltage on the far side 33kV, instrumentality is invariably put in in out of doors.

A station that is employed for all voltage levels between fifty-five kilovolt to 765 kilovolts is named out of doors station.

Such form of station needs less time for construction however uses extra space.

The out of doors substations area unit chiefly classified into 2 varieties, specifically pole-mounted station and foundation-mounted substations.

Underground Substation

In thickly inhabited areas, the house offered for instrumentation and building is restricted and the value of land is high.

underneath such conditions, the station is formed underground.

In this station all the instrumentation space assembled and also the substations are embedded by the fence for safety purposes.

The instrumentation needed for such kind of substations ar serious, and hence the positioning selected for such kind of station must have a decent path for heavy transport Pole

Mounted station Such substations are used for supporting distribution transformers having the capability of up to 250 kVA.

Such styles of transformers are the most affordable, simplest, and smallest of distributions.

All the instrumentation is that the out of doors kind and mounted on the supporting structures of high-tension distribution line.

Triple pole automatically operated switch used for the shift on and off the high-tension cable.

The electrical devices having a capability up to a hundred twenty-five kVA are mounted on the double pole structure and for the transformer having a capability between a

hundred twenty-five to 250 kVA 4-pole structure with the acceptable platform is employed.

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Ø  Easy to future extension

Ø  Low capital cost

Ø  Easy to fault location



Ø  More space is required

Ø  Operation is difficult

Step-Up station

The generation voltage is stepped up to high voltage to have an effect on the economy in the transmission of electrical power. This area unit usually settled within the power homes and area unit of an outside kind.

Such varieties of substations generate low voltage like three.3, 6.6, 11, or 33kV. This voltage is stepped up by the assistance of a transformer for transmittal the ability over giant distances. It’s settled close to the generating station.

Step-Down station

This station is placed close to the load Center wherever the first distribution is stepped down for sub-transmission. The secondary distribution electrical device feeds the patron through the line.

Primary Grid station

This station lowered the worth of primary stepped-up voltages. The output of the first grid station acts because of the input of the secondary substations. The secondary station is employed for stepping down the input voltage to a lot of lowered for more transmission.

Secondary Grid station

At a secondary station, the voltage is more steeped right down to 11KV. The 11KV lines run on the necessary road of the town. The secondary substations also are of an outside kind.

Distribution station

A distribution station transfers power from the gear mechanism to the distribution system of a region. The input for a distribution station is usually a minimum of 2 transmission or sub-transmission lines. Distribution voltages area unit usually medium voltage, between 2.4 and thirty-three potential unit counting on the dimensions of the world served and also the practices of the native utility.

Besides dynamic the voltage, the work of the distribution station is to isolate faults in either the transmission or distribution systems. Distribution substations may be the points of voltage regulation, though on long distribution circuits (several km/miles).


Pole mount substation

Pole mount substation is a substation that is situated form a is a small substation that is not required more space, it’s need only a pole. In this substation is step down substation

Distribution Substation of 33/11 kV

The Bangladesh Rural Electrification Board (BREB) has 33/11 kV distribution Sub Stations. Under this 33/11 kV distribution Substation Gazipur Palli Bidyut Samity-1 (GPBS-1) has 22 Substations. I am very lucky to say that I got an opportunity to od my internship into one of them. Which is situated as Gazipur Palli Bidyut Samity-1. 33/11 kV Substation Zajor Gazipur.

Substation of GPBS-1

The Zajor Palli Bidyut (Gazipur PBS-1) 33/11 kV distribution substation is situated beside the Head Quarter of the Gazipur PBS-1 in Zajor, Board Bazar, Dhaka. The type of substation is the 33/11 kV outdoor substation. This substation has a total of Two (2) power transformers of 10/12.5 MVA. The capacity of this substation is a total of 20 MVA. The substation has to take 33 kV source power as input from Power Grid Company Bangladesh Ltd. (PGCB). The total load of this substation is 18 MW.

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Single Line Diagram of GPBS-1 Substation

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Fig Single line diagram of 33/11 kV Substation GPBS-ii 

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