The Calculate EGU button 
is used with animations where Fetch Limits has been selected to set the percentage equation for the data source. Specifically, this is needed when using a DeltaV Operate on a remote workstation such as through a satellite linkup. Slow data transfers over some types of remote connections can cause the animation to operate at less than real-time speeds. Calculate EGU allows the animations to move at real-time speeds, that is, the picture of the tank will fill or empty, the agitators will rotate, and so forth, according to the real values without the data transfer connection delay.