This part is a kind of semiconductor called 3TK28xx.

Function of this product has Safety Integrated Application Manual.

Manufacturers : Siemens

Image and pinout :

Some of the text within the PDF file :

6.1 Switch Safely The following circuit examples have been harmonized with the German Trade Association (BG) and have been approved. • Contactor circuits • SIGUARD safety combinations using contactors using safety relays Suitable for: • EMERGENCY OFF • Protective door monitoring functions • Press controls EMERGENCY OFF circuits for extremely simple machines EMERGENCY OFF switch The EMERGENCY OFF function may only be fed through an EMERGENCY OFF switch for extremely simple machines, depending on the result of a risk analysis. In this particular case, only Stop Category 0 is possible. Such an EMERGENCY OFF switch switches, contrary to usual EMERGENCY OFF pushbuttons, the main circuit (circuit diagram 6/1). An EMERGENCY OFF switch must be configured, so that • There is only one E [ ... ]

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