 To assist the operators there are computer systems, with backups, which issue alarms when there are faults in the transmission or generation system.Power flow modeling tools let them analyze the state of their network, predict whether any parts of it may be overloaded, and predict the worst possible failure remaining, so that they can change the distribution of generation or reconfigure the transmission system to prevent a failure should this situation occur.If the computer systems and their backups fail, the operators are required to monitor the grid manually, instead of relying on computer alerts.