PJM works behind the scenes to ensure the reliability of the power grid and to keep the lights on. System Operations is responsible for managing the transmission and distribution grid. PJM coordinates and directs the operation of the region’s transmission grid. Power grid operators at PJM make real-time decisions that balance electricity supply and demand to keep the lights on. PJM performs “what if” scenarios all day long to assess conditions based on data from hundreds of thousands of points on the grid every four seconds.