My guess would be that it refers to some operating mode of the substation.
They have complex support systems and multiple operating modes.
However, as the steering ability of a ship is greatly reduced when running astern, it could not be considered a main operating mode.
Occupancy is one of two or more operating modes for a building automation system.
Synapse features four different operating modes that make up the development cycle.
Just didn't realize that was your normal operating mode.
It features several different operating modes, including "Auto" and manual.
One hundred percent of the rated capacity is the normal operating mode; those beyond 140 percent are considered likely to produce failure.
And most of the monitors have different operating modes.
Don't ask, don't tell is the operating mode for much of the nanotechnology industry these days when it comes to where discarded products end up.