Electrical Sub-Station

Introduction of Sub-Station

Substations play a crucial role in supplying energy to local areas. They receive high-voltage energy from generating stations, retread it to suitable levels for distribution, and facilitate switching operations. Substations can serve various functions, including safety device installation, voltage regulation, and housing equipment for street lighting. Let’s explore the nomenclature of substations based on variegated criteria.

“Substations are important in energy distribution, accommodating high-voltage energy for local supply, with a wide variety of types serving specific functions and voltage levels.”

1. Classification based on Nature of Duties:

• Step-Up or Primary Substations: Positioned in proximity to generating stations, these substations play a pivotal role in elevating the generated low voltage (e.g., 3.3, 6.6, 11, or 33 kV) to primary transmission levels. This transformation facilitates cost-effective long-distance power transmission to load centers.
• Primary Grid Substations: Strategically located withal primary transmission lines, these substations step lanugo primary transmission voltage to various suitable secondary voltages. The secondary transmission lines then proffer to secondary substations, situated at load centers, where remoter voltage reduction occurs for sub-transmission or primary distribution.
• Step-Down or Distribution Substations: Serving load centers directly, these substations remoter reduce sub-transmission or primary distribution voltage to the secondary distribution level (415/240 V), ensuring the efficient supply of energy to end consumers.

2. Classification based on Service Rendered:

Transformer Substations: These substations primarily house transformers, essential for interchange power from one voltage level to another, meeting diverse energy demands.
• Switching Substations: Defended to switching operations, these substations facilitate the reconfiguration of power lines without interchange voltage levels.
• Converting Substations: Specialized in interchange the nature of power, these substations can convert successive current (AC) to uncontrived current (DC) or vice versa. They can moreover modify frequency, catering to specific requirements.

3. Classification based on Operating Voltage:

• High Voltage Substations (HV Substations): Operating within the voltage range of 11 kV to 66 kV, these substations are crucial nodes in the distribution network.
• Extra Upper Voltage Substations (EHV Substations): Operating between 132 kV and 400 kV, these substations handle higher voltage levels, contributing to long-distance power transmission.
• Ultra Upper Voltage Substations (UHV Substations): Operating whilom 400 kV, these substations are key players in managing extremely upper voltage levels.

4. Classification based on Importance:

• Grid Substations: Serving as pivotal points in the energy grid, these substations facilitate the zillion transmission of power between variegated points. Any disturbance in these substations can potentially lead to grid failure.
• Town Substations: Essential for urban energy distribution, these substations step lanugo voltages for remoter distribution within towns. Failures in these substations can result in widespread power outages.

5. Classification based on Design:

• Indoor Type Substations: Equipped with workings housed within a defended building, these substations are suitable for voltages up to 11 kV. They can moreover be erected for higher voltages (33 kV and 66 kV) when the surrounding environment is contaminated with impurities such as metal corroding gases and fumes, conductive dust, etc.

• Outdoor Substations: Remoter classified into pole-mounted and foundation-mounted substations based on transformer capacity.

(a) Pole-Mounted Substations: Designed for local power distribution, these substations utilize single stout poles or structures with suitable platforms.

(b) Foundation-Mounted Substations: Reserved for transformers with capacities exceeding 250 kVA, these substations are typically used for voltages of 33,000 volts and above.

In essence, substations are indispensable components in the intricate web of energy distribution networks, ensuring the seamless and efficient supply of power to diverse locations. Their classifications based on diverse criteria highlight the versatility and complexity of these essential energy infrastructure components.


Substations play an important role in local energy supply by receiving and accommodating high-voltage energy for distribution.

Types based on duties:

Step-up: Located near generating stations, it steps up low voltage for long distance transmission.
Primary Grid: Located along the transmission lines, it steps down the voltage for further distribution.
Step-down: Acts directly on the load centres, reducing the voltage to the consumer supply.

Types based on service:

Transformer: Housing transformers for various energy demands.
Switching: Facilitates power line reconfiguration.
Converting: Specializing in changing the nature, voltage and frequency of electricity.

Types depending on voltage:

High Voltage: Operates between 11 KV to 66 KV.
Extra Upper Voltage: Handles 132 KV to 400 KV for long distance transmission.
Ultra Upper Voltage: Manages extremely high voltage levels in excess of 400 KV.

Types based on importance:

Grid: Critical to the energy grid; Any disturbance can cause grid failure.
Cities: Essential for urban energy distribution, failures cause massive power outages.

Types based on design:

Indoor: equipped with protected buildings for voltage up to 11 kV; Used in contaminated environments.
Outdoor: This includes pole-mounted for local distribution and foundation-mounted for higher capacity and voltage.