✦ Short Answer:

Insulation in high-voltage transmission is used to prevent electrical current from leaking out of the conductors and to protect people, equipment, and the surrounding environment from electric shocks or damage. It acts as a barrier that keeps the high-voltage current safely confined within the wire or transmission line.

The main purpose of insulation is to ensure safe and reliable operation of the power system. Without proper insulation, high-voltage electricity could jump to nearby objects or the ground, causing faults, power outages, or serious accidents. Insulation also helps maintain system efficiency and reduces energy losses.

Detailed Explanation:

Purpose of insulation in high-voltage transmission

❖ Why Insulation is Important

In high-voltage transmission systems, electrical energy flows at very high voltages—often above 100,000 volts. At such high levels, even air can become a conductor if the insulation is not adequate. Therefore, insulation is used to control the electric field and prevent any unwanted flow of electricity outside the conductor. It ensures that the electricity stays within the wires and does not escape to the tower, ground, or nearby objects.

❖ Main Functions of Insulation

1. Preventing Leakage Current
   Insulation acts as a protective layer around conductors, stopping any leakage of current. This ensures the power flows smoothly from one point to another without unnecessary losses.
2. Ensuring Safety
   High voltages can be very dangerous. Proper insulation protects people and animals from coming into direct contact with live wires. It also prevents arcing, which can cause fires or damage nearby structures.
3. Avoiding Short Circuits and Faults
   Without insulation, current may jump from one phase conductor to another or to the ground. This can lead to short circuits, tripping of circuit breakers, and disruption in power supply. Insulation helps avoid such problems.
4. Maintaining System Efficiency
   Insulated systems reduce the chances of energy being lost into the environment. This increases the efficiency of power transmission and ensures that more energy reaches the end user.
5. Protecting Equipment and Infrastructure
   Insulation prevents damage to transmission towers, poles, and other supporting structures by avoiding direct current contact. This helps in increasing the life of equipment.

❖ Types of Insulation Used in High-Voltage Transmission

1. Air Insulation
   In overhead lines, air itself acts as the primary insulating medium. The wires are held high above the ground and spaced apart to use air as insulation.
2. Solid Insulation
   Materials like porcelain, glass, or polymer are used in insulators to support and separate conductors from towers.
3. Oil and Gas Insulation
   In underground cables and transformers, special oils and gases like SF₆ (sulfur hexafluoride) are used to insulate and cool the components.
4. Composite Insulators
   Modern high-voltage lines use composite insulators that combine rubber or polymer with other materials. These are lightweight and weather-resistant.

❖ Where Insulation is Applied

• On Overhead Transmission Lines: Using disc or long-rod insulators to keep wires away from towers.
• In Transformers and Substations: Using insulating oils, bushings, and barriers to prevent faults.
• In Underground Cables: Using multiple insulation layers around the conductor to ensure safety under the ground.

✦ Conclusion

Insulation in high-voltage transmission is extremely important for the safety, reliability, and efficiency of the power system. It prevents dangerous current leaks, protects equipment and people, and ensures smooth flow of electricity without losses or faults. Whether in the form of air gaps, solid insulators, or advanced materials, insulation is a vital part of every high-voltage transmission network. Without proper insulation, the entire system would be unsafe and inefficient.