The Apocalypse

Appearance

Long-distance grid ​

High-voltage transmission lines are the backbone of modern electrical infrastructure, enabling efficient transport of large amounts of electricity over vast distances. This section covers the principles, components, construction, operation, and maintenance of high-voltage (HV) transmission grids essential for rebuilding industrial society after an apocalypse.

Introduction to High-Voltage Transmission ​

Electricity generated at power plants must be delivered to consumers often located many miles away. Transmitting electrical power over long distances at low voltages results in excessive energy losses due to resistance in conductors. To minimize these losses, electrical power is stepped up to high voltages—typically ranging from 69 kV (kilovolts) to over 765 kV—before transmission. High voltage reduces current for the same power level, which lowers resistive losses (I²R losses) and allows for thinner, lighter conductors.

High-voltage transmission lines form a network known as the transmission grid. This grid interconnects power generation sources with substations near load centers, where voltage is stepped down for distribution to homes, businesses, and industries.

A photo of a high-voltage transmission tower standing tall in a rural landscape during sunset, with multiple power lines extending into the distance.

Fundamental Principles of HV Transmission ​

Electrical Power and Transmission Losses ​

Electrical power (P) is the product of voltage (V) and current (I):
P = V × I

For a given power level, increasing voltage reduces current proportionally:
I = P / V

Resistive losses in conductors are proportional to the square of the current:
Loss = I² × R

By increasing voltage and reducing current, resistive losses decrease significantly, improving transmission efficiency.

AC vs. DC Transmission ​

Most long-distance transmission grids use alternating current (AC) because it is easier to transform voltages using transformers. However, high-voltage direct current (HVDC) transmission is increasingly used for very long distances or underwater cables due to lower losses and better control over power flow.

This section focuses primarily on AC transmission, as it is the foundation for rebuilding a regional or national grid.

Components of a High-Voltage Transmission Grid ​

Transmission Lines ​

Transmission lines consist of conductors suspended by towers or poles. Common conductor materials include:

  • Aluminum conductor steel-reinforced (ACSR): Aluminum strands for conductivity with a steel core for strength.
  • All-aluminum alloy conductors (AAAC): Lightweight and corrosion-resistant.
  • Copper conductors: Excellent conductivity but heavier and more expensive.

Conductors are bundled in multiple sub-conductors per phase to reduce corona discharge and increase capacity.

Towers and Poles ​

Transmission towers support conductors at safe heights and maintain phase clearance. Types include:

  • Lattice steel towers: Common for high voltages and long spans.
  • Tubular steel poles: Used in urban or constrained areas.
  • Wooden poles: Suitable for lower voltage lines or temporary installations.

Towers are designed to withstand mechanical loads from conductors, wind, ice, and seismic activity.

Insulators ​

Insulators prevent electrical current from flowing to the tower structure. Types include:

  • Porcelain insulators: Durable and widely used.
  • Glass insulators: High mechanical strength and visibility for damage.
  • Polymer insulators: Lightweight and resistant to vandalism.

Insulators are arranged in strings to provide sufficient voltage withstand capability.

Substations ​

Substations are nodes in the grid where voltage is transformed, power flow is controlled, and protection equipment is installed. Key substation components:

  • Power transformers: Step voltage up or down.
  • Circuit breakers: Interrupt fault currents to protect equipment.
  • Busbars: Conductors that interconnect equipment.
  • Switchgear: Devices to isolate or connect parts of the grid.
  • Capacitor banks and reactors: Manage reactive power and voltage stability.

A high-voltage transmission tower with labeled parts: conductor, insulator string, crossarm, and grounding wire on a white background with black line art.

Construction of High-Voltage Transmission Lines ​

Route Planning and Right-of-Way ​

Selecting the transmission line route requires balancing technical, environmental, and social factors:

  • Minimize length to reduce costs and losses.
  • Avoid populated areas to reduce hazards and opposition.
  • Consider terrain, vegetation, and land use.
  • Secure legal rights-of-way for construction and maintenance access.

Foundation and Tower Erection ​

Tower foundations depend on soil conditions and tower type:

  • Concrete foundations: Common for lattice towers, designed to support vertical and lateral loads.
  • Driven piles: Used in soft or unstable soils.
  • Anchors and guy wires: Provide additional stability for some tower designs.

Towers are assembled on-site or pre-fabricated and erected using cranes or helicopters.

Conductor Stringing ​

Conductor installation involves:

  • Pulling conductors with tension control to prevent damage.
  • Installing vibration dampers to reduce mechanical fatigue.
  • Attaching grounding wires (shield wires) above conductors to protect from lightning.

Safety Measures During Construction ​

  • Use of personal protective equipment (PPE) for workers.
  • Strict adherence to electrical safety protocols.
  • Coordination with local authorities and landowners.

A photo showing workers in safety gear stringing conductors on a high-voltage transmission tower, with clear blue sky background.

Operation and Maintenance of HV Transmission Grids ​

Monitoring and Control ​

Modern grids use Supervisory Control and Data Acquisition (SCADA) systems to monitor voltage, current, and equipment status remotely. This enables rapid response to faults and load changes.

Routine Inspections ​

Regular inspections detect issues such as:

  • Corrosion or damage to conductors and towers.
  • Insulator contamination or cracks.
  • Vegetation encroachment causing fire or fault risks.
  • Loose hardware or grounding problems.

Inspections are performed visually, with drones, or using infrared thermography to identify hot spots.

Vegetation Management ​

Vegetation near transmission lines is a major cause of outages and fires. Maintaining clearances through trimming or removal is essential.

Fault Detection and Repair ​

Common faults include:

  • Lightning strikes causing flashovers.
  • Conductor breaks due to mechanical failure.
  • Short circuits from tree contact or animals.

Rapid fault isolation using circuit breakers and repair crews minimizes outage duration.

Upgrading and Expansion ​

As demand grows, grids may require:

  • Adding new lines or circuits.
  • Upgrading conductors to higher capacity.
  • Installing series capacitors or FACTS devices for voltage control.

Safety Considerations ​

Electrical Hazards ​

High voltages pose lethal risks. Safety protocols include:

  • Maintaining minimum approach distances.
  • Using insulated tools and equipment.
  • Grounding lines before work.

Environmental Impact ​

Transmission lines can affect wildlife and ecosystems. Mitigation measures:

  • Bird diverters to reduce collisions.
  • Avoiding sensitive habitats.
  • Using underground cables in urban or protected areas where feasible.

Public Safety ​

  • Clear signage and fencing around substations.
  • Public education on dangers of climbing towers or touching downed lines.

A safety warning sign showing a high-voltage hazard symbol on a white background with black line art.

Rebuilding a Long-Distance Grid After Collapse ​

Assessing Existing Infrastructure ​

  • Inspect surviving towers, lines, and substations for damage.
  • Prioritize repair of critical links to restore regional power flow.

Sourcing Materials and Equipment ​

  • Salvage conductors, insulators, transformers, and hardware from abandoned sites.
  • Manufacture replacement components using local industry capabilities described in earlier chapters.

Workforce Training ​

  • Train technicians in line construction, maintenance, and safety.
  • Establish teams for vegetation management and emergency response.

Grid Design Principles ​

  • Build redundancy with multiple paths to improve reliability.
  • Implement sectionalizing switches to isolate faults.
  • Plan for future expansion and integration of renewable generation.

Integration with Generation and Distribution ​

  • Coordinate with power plants to match generation capacity and load.
  • Ensure voltage levels and protection schemes are compatible across the grid.

Conclusion ​

High-voltage transmission grids are critical infrastructure for restoring industrial society’s electrical power system. Understanding the electrical principles, components, construction methods, operation, and safety practices enables survivors to rebuild and maintain a reliable long-distance grid. This foundation supports all subsequent levels of industrial and technological recovery.

For foundational knowledge on manual lumber processing and charcoal production needed to build towers and insulators, see Manual lumber processing and Charcoal production and clay kilns.

A photo of a panoramic view of a high-voltage transmission corridor crossing a valley with multiple towers and lines stretching to the horizon under a clear sky.