This invention relates to a speed monitor apparatus for monitoring speed and acceleration of rotating turbine equipment (turbomachinery) and for operating an overspeed trip to shut down the equipment in the event that the speed or acceleration exceed predetermined thresholds. The invention provides a speed monitor module having an output switch comprising a plurality of armature clamped relays such that first armatures form a first electrical path only when both first armatures are open or when both first armatures are closed and second armatures provide a second electrical path when either or both second armatures are open or closed such that the second electrical path is discontinuous when either first armature is stuck in an open or closed position causing either second armature to remain floating between an open and closed position.