Black start

A black start is the process of restoring an electric power station, a part of an electric grid or an industrial plant, to operation without relying on the external electric power transmission network to recover from a total or partial shutdown. Power to restart a generating station or plant may come from an on-site black start standby generator. Alternatively, where a large amount of power is required, a tie-line to another generating plant or to an emergency generator may be used to start the facility. Once the main generating units are running, the electrical transmission network can be re-connected and electrical loads restored. Black-start power may be ensured by an agreement where a particular energy supplier is paid to make black start power available when required. Not all generating plants are suitable for providing black-start power to a network. The ability to perform a black start requires complex technology and is economically costly. In addition, the power plant providing the black start must be located close to the electricity users.