Victron Energy automatic transfer switches: the VE Transfer Switch at 5kVA and 10kVA, 230V, for switching between two AC sources, and the Filax 2, an ultra-fast transfer switch with a changeover time of a few milliseconds.
The difference is time: an electromechanical transfer switch changes over in tens of milliseconds, fine for lights and fridges but not for sensitive equipment. The Filax 2 comes in under 20 milliseconds and was built to let shore power and an inverter share a boat or a motorhome with no interruption you can notice.
They are sized on the current of the line being switched, allowing for inrush from inductive loads.
