Civilization's demands for electricity continue to grow, yet environmental, regulatory, and economic constraints often preclude the construction of new power plants and transmission lines. The challenge now faced by engineers, equipment manufacturers, and regulatory agencies is to find ways to maximize the capacity of existing power lines.Powerline Ampacity System is the first step in meeting that challenge. Along with developing a complete theory of transmission line ampacity, the author uses object-oriented modeling and expert rules to build a power line ampacity system. He describes new transmission line conductor technologies and power electronics FACTS devices that can take full advantage of a dynamic line rating system. He offers examples that clearly show the economic benefit of operating an interconnected transmission network that has a diverse mix of electricity generation sources. He also discusses - with examples - generator stability enhancement by dynamic line rating.