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What are the main components of a substation

After I wrote about the electrical sub-station, I came to know many of you are searching for, what are the main components of a substation? So, I today would like to discuss about the very important components used in an electrical sub-station. Before reading this post, I am suggesting you to read the post about Electrical Sub-station is linked below.

Electrical substation is a crucial section of power system. In order to deliver the electric power from power generating stations to the consumers, it may desired to change some characteristics (e.g voltage, frequency) of electricity supply. To perform the duty an assembly of apparatus is used called sub-station. The sub-station is consists of many electrical components. These are listed and described below.

Main components of a substation

  1. Power Transformer
  2. Current Transformer
  3. Potential Transformer
  4. Insulator
  5. Isolator
  6. Busbar
  7. Circuit breakers
  8. Lightning Arrester
  9. Capacitor Bank
  10. Relay

1. Power Transformer

Power transformer or simply transformer is the main component for a transformer substation also called is distribution substation. In distribution substation, step down transformer is used to down the high voltage power in a utilization level, literally from 33kV or 11 kV to phase to phase 440 volt and phase to neutral 220 volt. In power generation substation, step up transformer is used to step up the voltage level for economic transmission.

Power transformer

2. Current Transformer

Current transformer or CT is a current transforming device. It transforms a high value current to low value. It’s primary current is always proportional to the secondary current. The current transformer is used with the AC instrument, meters or control apparatus where the current to be measured is of such magnitude that the meter or instrument coil cannot conveniently be made of sufficient current carrying capacity. The current transformer is shown in the figure below.

Current transformer

3. Potential Transformer

Potential transformer or PT is a device like current transformer. But the difference between them, PT is used for reducing voltage level. It’s a type of step down transformer. The PT step down the voltage level in a safe limit value which can be measured by the ordinary low voltage measuring instruments like volt meter, watt meter etc.

Potential transformer

4. Insulator

Insulators are such materials which does not allow current to be flowed. It’s also called none-conductive material. Insulators are used to prevent unauthorized current flow between two or more conductors. It protects short circuit and human body. There are 3 types of Insulators.

i. Pin type, ii. Strain type and iii. Suspension type.


5. Isolator

An isolator is a mechanical switching device. It is used to isolate an electrical circuit or equipment on off load condition. When any fault occurs or maintenance purpose, the required section of substation is isolated by isolator. There are 3 types of isolator.

i. Single Break Type, ii. Double Break Type and iii. Pantograph Type Isolator.


6. Busbar

Busbar is one of the main component of substation. Busbar is a metal bar which is composed of copper, brass or aluminum. It is a type of electrical junction in which all incoming and outgoing current meets. Most commonly used Busbar type is a type of rectangular solid bar. A Busbar receives electricity from many sources in same characteristic and supply to the different feeders or load. Circuit breakers are deployed at the both end of a busbar.


7. Circuit Breaker

Circuit Breaker is a switching device and at the same time it’s a protecting device too. Circuit breaker can automatically break or open an electrical circuit at any fault condition. It is also operated manually for opening and closing an electrical circuit.

Circuit Breaker

8. Lightning Arrester

Lightning arrester is a protective device. It receives the high voltage produced by Lightning strike and delivers to ground. Lightning arrestor has two terminal. One terminal is connected to live wire and another terminal with ground. When Lightning strike occurs then a high voltage produced in power line which can burns the power line and equipment. Lightning arrester protects the power system from Lightning strike.

Lightning arrester

9. Capacitor Bank

Capacitor bank means a set of capacitor. It is necessary for improving the power factor of electrical power system.

Capacitor bank

10. Relay

Relays are basically sensing gadgets which are devoted for sensing faults and are determining its location as well as sending interruption message of tripped command to the specific point of the circuit. A circuit breaker is falling apart its contacts after getting the command from relays. These are protecting equipment from other damages as well such as fire, the risk to human life, and removal of fault from a particular section of the substation.


Apart from these, there are many components used in a substation. I will discuss about those in my another post. Thanks for your patience reading.

Now, give answer to some questions below based on the topic, What are the main components of a substation. It will help you to boost up your knowledge on this topic.

Please, at first provide your name and email.

Your name
Your email
What kind of power transformer is used in distribution substation?
Current transformer (CT) is a kind of step-down transformer.
Potential transformer can reduces voltage level.
How many type insulators are discussed in this post?
Busbar is composed of
MCCB is a type of circuit breaker.
Lightning Arrester is a type of insulator.
Which device is used to improve power factor?
Relay is a protecting device

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