Grid Substation

Grid substations are essential for voltage conversion, power distribution, and system protection. During my CEB industrial training, I observed key components that ensure efficient and safe power transmission.

Main Components of the Substation

❇Surge Arrester – Protects the system from sudden voltage spikes due to lightning or switching operations
❇Capacitor Voltage Transformer (CVT) – Reduces high voltage for metering, protection, and power line communication.
❇Isolator – Provides a visible break in the circuit for safe maintenance and isolation of equipment. There have Bus isolators and line isolators
❇Current Transformer (CT) – Steps down high current to measurable levels for protection relays and metering.
❇Circuit Breaker (CB) – Automatically interrupts fault currents, preventing damage to transformers and power lines.
Eg : SF6 (Uses sulfur hexafluoride (SF₆) gas to extinguish arcs and safely interrupt fault currents.)
❇Busbar – Conducts and distributes high-voltage electricity between different parts of the substation
❇Power Transformer – Converts 220kV to 132kV and 33kV, making voltage suitable for transmission and distribution.
❇ Variable Shunt Reactor (VSR) - It is a device used in power systems to manage reactive power. It helps control the voltage by absorbing excess reactive power when voltage levels are too high. The VSR can adjust how much reactive power it absorbs, allowing it to stabilize the voltage in transmission lines and improve the overall efficiency of the system.
❇Earth Transformer – Provides neutral grounding, ensuring system stability and fault protection
❇Auxiliary Transformer – Supplies power for substation control systems, lighting, and cooling systems.

Substation Types & Design

🔸 Air-Insulated Substation (AIS) – Uses open-air insulation for components, making maintenance easier and low initial cost

🔸 Gas-Insulated Switchgear (GIS) 🏗 – Compact design with enclosed switchgear for higher reliability in limited spaces.