Gps timestamped electrical measurements are sent over fiber optic cables between substations on either end of transmission lines to make sure current in is the

Gps timestamped electrical measurements are sent over fiber optic cables between substations on either end of transmission lines to make sure current in is the same as current out, roughly. Also for measuring and controlling power flows. https://www.smartgrid.gov/recovery_act/program_impacts/applications_synchrophasor_technology.html https://www.smartgrid.gov/recovery_act/program_impacts/appli...