In a continuous process plant what is the time span a dcs can control the plant without any manual operations or supervisory acts?? One of my friend is working is a power plant and says there dcs cant control the plant more than 15mins without any operator. They have to watch the process every time. But when any process is automated i think its made to have max control by its controller and control the process for long times without any manual or supervisory action other than in some critical failure conditions.