The bulk transfer of electrical power takes place through a delivery system or process known as electric power transmission. Here the transfer takes place between the power plant and the substation nearer the consumer unlike electricity distribution where the transfer takes place from the substation to the consumer. This allows for distant energy sources to maintain a connect to populated areas economically. Large amounts of power at a high voltage of 110 kv or above are involved in the process of delivery of electricity to consumers, in the bulk transfer of electrical power. Due to this low-grade fuel resources can be exploited which would otherwise be expensive transport to generating facilities.
Overhead power transmission lines are usually used to transmit electricity over long distances. Densely populated areas use underground power transmission due to high installation and maintenance, and also because high reactive power produces large charging currents and voltage management difficulties.
Sometimes referred to as a grid, for reasons of economy a power transmission systems network is not a mathematical grid. Redundant paths and lines are provided for power to be routed from power plants to load centers through routes based on the economics of the transmission paths and the cost of power. Transmission companies determine the maximum reliable capacities of each line after analysis. Deregulation of electricity companies in many countries may have led to renewed interest in reliable economic design of transmission networks.