Guidelines for the use of underground cable systems and overhead conductor systems

Introduction:

Distribution of electricity involves the transfer of electrical energy through sub-transmission and distribution lines, which can be overhead lines or underground cables.

Each type has its benefits and drawbacks, with the choice depending on factors like safety, cost, right of way, and aesthetic considerations.

1.?????? Overhead Network:

Uses structures like poles or towers to suspend conductors.

Consists of various components such as poles, conductors, insulators, stay wires, and grounding materials.

Conductors can be bare or insulated, with choices based on factors like power carrying capacity, cost, and reliability.

Aerial Bunched Cables (ABC) are a good option for overhead LT distribution, providing higher safety, reliability, and system economy.

2.?????? Underground Network:

Power is transferred through cables laid underground, providing an aesthetic look and less susceptibility to outages due to weather conditions.

Cables consist of conductor, insulation, bedding, armoring, and outer sheath.

Faults in underground cables require specialized techniques for location and repair, which can be time-consuming and costly.

3.?????? Comparison - Feasibility Analysis:

• Cost of Installation: Underground network installation is more expensive due to cable and road restoration costs.
• Fault Location Identification & Repairing Time: Identifying faults in underground cables is more challenging and time-consuming.
• Cost of Repairing a Fault: Repairing faults in underground cables is more expensive than in overhead lines.
• Line Outage Durations: Underground system repairs can lead to longer customer outages.
• Line Modifications: Underground lines are more difficult and expensive to modify.
• Effect from Weather Conditions: Overhead lines are more prone to damage from severe weather conditions.
• Range of Electromagnetic Fields (EMF) Emission: Underground cables produce less external magnetic field than overhead lines.
• Space Requirement: Underground cables do not require physical ground space, unlike overhead lines.
• Hazard to Wildlife: Underground cables pose no hazard to wildlife compared to overhead lines.
• Illegal Connection/Theft of Power/Pilferage: Underground cables are less susceptible to illegal connections or theft.
• Aesthetics: Underground cables provide a cleaner and more aesthetic view compared to overhead lines.
• Flexibility to Increase Line Capacity: Overhead lines can be easily upgraded, while underground cables need to be supplemented or replaced.
• Line Life: Insulation deterioration is faster in underground cables compared to overhead conductors.
• Safety: Underground cables do not require minimum safety clearances like overhead lines.

These guidelines provide a comprehensive overview of the factors to consider when choosing between underground cable systems and overhead conductor systems, including their costs and benefits.