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 wherein the speed monitor module may be may be plugged in to the same chassis as a module which is controlling the speed of the turbine, and wherein the turbine speed monitor is arranged to receive configuration parameters relating to the overspeed threshold and the overacceleration threshold only when the turbine is operating at a speed lower than a predetermined threshold.