Siemens Fault signal contact, 2NO for mini circuit breakerProduct Overview The Siemens 5ST3021 is a professional fault signal contact accessory designed for monitoring and signaling the automatic tripping status of Siemens miniature circuit breakers and residual current devices. This dual normally open (2 NO) contact module provides essential status feedback for building management systems, alarm panels, and monitoring applications, enabling remote indication when circuit protection devices have