The Daresbury personnel safety system

The personnel safety system designed for the Synchrotron Radiation Source (SRS) at Daresbury is a unified system covering the three accelerators of the source itself, the beamlines, and the experimental stations. The system has also been applied to the experimental areas of the Nuclear Structure Facility, and is therefore established as a site standard. A dual guardline interlock module forms a building block for a relay-based interlock system completely independent of the machine control system, although comprehensive monitoring of the system status via the control system computer is a feature. An outline of the design criteria adopted for the system is presented together with a more detailed description of the philosophy of the guardline logic and the way this is implemented in a standard modular form. The emphasis is on the design features of a modern microprocessor-based variant of the original SRS system. Experience with the original system during buildup and operation of the SRS facility is described.<>