For example, sudden, dark storm clouds will increase demand because many lights will be turned on. The load dispatcher forecasts changes in demand and adjusts the generation and transmission of power accordingly. When demand exceeds the generating capacity of a power plant, the load dispatcher may reduce the voltage to prevent a blackout. Such a situation, called a brownout, may damage electrical equipment or cause it to operate less efficiently. The transmission networks of most electric companies are interconnected, forming a power pool.
Power pools enable companies to receive power from one another in an emergency.
Computers control the flow of electric current through transmission networks. The electric power industry Organizations that generate, transmit, or distribute electric power are called electric utilities. In most countries, nearly every electric utility is the sole supplier of electric power in a particular area. Government agencies regulate electric utilities to ensure that they serve the needs of the public. In some countries, the government owns all electric utilities.