The 3RT19161DG00 is a surge Suppressor Diode Module. The surge suppressor is plugged onto the front of size contactors. Space is provided for them next to a Snap-On auxiliary switch block. A varistor is integrated in the timer module in order to damp opening surges in the contactor coil.
Integrated Surge Suppressor (varistor) for the Contactor Coil being Switched