Abstract: An electromagnetic switching device for operationally switching currents in the load range and having an instantaneous release, connected in series, for protection against welding of the contacts (6) in the overload range is created, and has a high reliability and low overall volume. The electromagnet (2) of the switching device (1) is arranged in the middle relative to the contact bridge carrier (8) and coupled directly to the latter in the middle. The instantaneous release (3) acts via a rocker (15) on the movable contact (6) and is actuated only in the case of overcurrents, use being made of the fact that only the directly coupled drive system of the switching device is employed in the nominal current range.

Abstract: An expandable automation system includes both a programmable controller that is capable of stand-alone operation, and a modular programmable controller. The programmable controller that is capable of standalone operation has an interface, such as a multipole plug connector, for connecting expansion units. The modular programmable controller consists of a central processing unit and expansion modules. The expansion modules of the modular programmable controller can be used as expansion units for the programmable controller that is capable of standalone operation.