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Basics of Electric Power Transmission


From UPSC perspective, the following things are important :

Prelims level : NA

Mains level : Power transmission

power transmission

Central Idea

  • In 1954, India’s first Prime Minister, Jawaharlal Nehru, referred to dams as “the temples of modern India” during a visit to the Bhakra Nangal Dam site.
  • This statement emphasized the critical role of electricity in the nation’s development and its transmission as the cornerstone of economic progress.

This article offers a simplified introduction to the world of electric power transmission.

Three Components of Power Supply

  1. Generation: Electricity is generated at power plants, including renewable energy installations.
  2. Transmission: It involves the distribution of electricity through a network comprising substations, switches, overhead and underground cables, transformers, and more.
  3. Distribution: The final step is delivering electricity to consumers, tailored to the requirements of various machines and applications.

Key Principles of Electric Power Transmission

  • Efficiency and Voltage: Lower current and higher voltage enhance transmission efficiency. Transformers play a crucial role in voltage manipulation, stepping it up before transmission and reducing it for consumers.
  • Resistance and Cable Thickness: Transmission cables exhibit resistance, leading to energy loss. Thicker cables minimize losses but also increase costs.
  • Distance and Transmission Cost: Longer transmission distances result in lower costs.
  • Alternating Current (AC): AC power transmission is predominant due to its adaptability and higher efficiency compared to direct current (DC). However, higher AC frequencies result in increased resistance.

Understanding AC Power

  • Three-Phase AC: AC power transmission commonly utilizes three-phase AC, where voltage periodically changes polarity.
  • Phases in AC: In a three-phase AC circuit, three wires carry AC current in different phases, typically at 120°, 240°, and 360°.
  • AC in Household Appliances: Consumers receive three-phase AC power, which is used in household appliances for ease of control.

Transmission Process

  • Voltage Stepping: Voltage is stepped up at power plants using transformers before being transmitted.
  • Transmission Lines: Suspended from transmission towers, transmission lines carry the electricity across long distances.
  • Safety Measures: Insulators, circuit-breakers, grounding, arresters, and dampers ensure safe and stable transmission.
  • Switches: Used to control current availability and to redirect currents between lines.
  • Substations: Different types of substations perform tasks like power collection, frequency modification, voltage reduction for distribution, and diagnostics.

Operation of Power Grids

  • National Grids: A national grid encompasses generation, transmission, and distribution. It must accommodate various power sources, production locations, and consumption patterns.
  • Storage Facilities: Grids include storage systems to manage surplus and deficit power supply.
  • Flexible Sources: Gas turbines and automated systems respond to fluctuating consumer demand or emergencies.
  • Grid Management: Grids maintain synchronized frequencies, manage demand, control voltage, and improve power factor.
  • Wide-Area Synchronous Grids: Such grids, where all generators produce AC at the same frequency, result in lower costs but require measures to prevent cascading failures.

Key agencies in Power Transmission

India’s power transmission sector relies on key agencies to manage and enhance the electricity grid. These include:

  • State Transmission Utilities (STUs): Managing intrastate power transmission within each state.
  • National Load Despatch Centre (NLDC): Maintaining national power balance and grid security.
  • Regional Load Despatch Centres (RLDCs): Overseeing regional power operations and grid stability.
  • Central Electricity Regulatory Commission (CERC): Regulating tariffs and power transmission at the national level.
  • State Electricity Regulatory Commissions (SERCs): Regulating power transmission within individual states.
  • Private Transmission Companies: Collaborating with government agencies for grid expansion and modernization.


  • Electric power transmission is a complex but vital aspect of modern civilization, serving as the backbone of economic development.
  • Understanding its basic principles sheds light on the intricate network that powers our lives and fuels progress.

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