Bulk electric system (BES)

The bulk electric system (BES) comprises multiple generators and storage facilities that connect into the high-voltage transmission system as well as the transmission system itself. The transmission system consists of multiple lines that transport power, transmission substations that connect lines of different voltages, interconnections with neighboring transmission systems, and various protective, monitoring, and control devices. The BES ends at the interconnection to a distribution substation called the transmission-distribution, or T-D, interface.