Vibration monitoring and alarm system

This report describes a system designed for use in nuclear power stations, or at other infrastructure sites, where a rapid response may be required when the ground acceleration caused by an earthquake exceeds a certain threshold. The system uses free-field acceleration measurement to trigger a physical alarm. The data acquisition and alarm functions are carried out on a PC that then triggers an alarm by use of a relay. The system described here has two such PCs for redundancy, although a single PC could perform the required task.