AEC VacTrac Series Conveying Systems - Manual (Page 41)

Page 40 12-Station Controllers VacTrac™ Conveying Systems
LOADING/IDLE (2 Pump Mode Only)
In Dual Pump mode, if you start the controller with demand from
stations assigned to both pumps, both pumps start at the same time.
In many plants, such a resulting power surge can momentarily
exceed the electrical limits of the plant. To prevent this condition,
the pumps are staged in sequence separated by a short duration.
Pump 1 always starts first, followed by Pump 2.
This state also applies when both pumps are in the OFFLINE state
and demand occurs on both systems at the same time.