User`s manual

page 20
Smooth Start
The Smooth Start feature of the STP line of power inverters is
designed to handle the power surge that is created when some
appliances are turned on. This feature helps protect both the
appliance and the inverter from excessive power draws and surges.
When the power switch is turned on, the STP inverter smoothly
brings up the AC power. This circuitry also activates under
excessive loads, even short circuits, to quickly turn off power to
protect the device and the inverter. The STP inverter then
automatically attempts to smoothly bring up the AC power, unless
it detects an excessive load.