Smart Machine Protection System*

A Machine Protection System implemented on the SLC automatically controls the beam repetition rates in the accelerator so that radiation or temperature faults slowthe repetition rate to bring the fault within tolerance without shutting down the machine. This process allows the accelerator to aid in the fault diagnostic process, and the protection system automatically restores the beams back to normal rates when the fault is diagnosed and corrected,,The user interface includes facilities to monitor the performance of the system, and track rate limits, faults, and recoveries. There is an edit facility to define the devices. to be included in the protection system, along with their set points, limits, and trip points. This set point and limit data is downloaded into the CAMAC modules, and the configuration data is compiled into a logical decision tree for the 68030 processor. INTRODUCTION The Stanford Linear Collider includes a number of safety systems that shut down the Collider when unsafe conditions a%?-When the Collider shuts down, it becomes difficult to diagnose the cause of the problem. Often it becomes necessary to terminate the startup multiple times before the problem(s) are corrected and safe continuous operation can resume. Substantially more effective operation would result from a safety system that would report the cause of the fault from the origin of the equipment trip, allowing safe, lower repetition-rate operation to continue, so that the machine can be used to diagnose itself. Automatic return to higher-rate operation after repairs speeds recovery and allows automatic handling of system glitches. PROPOSED ENGINEERING SOLUTION A new Machine Protection System (MPS) is being installed in the SLC that will improve machine protection and utilization. The new system will continue to detect, unsafe conditions on a pulseto-pulse basis; however, it will now rate-limit the machine to continue operation at safe levels for diagnostic purposes. This new system utilizes stand-alone array processors to scan the set of fault detectors (radiation, temperature, flows, etc.), making rate limit decisions based on the type and severity of any detected faults, using machine configuration and parameter limit tables developed by machine and radiation physicists. Facilities have been included to support logging of all machine state changes; the protection system forwards a message to the control room explaining which input signal faulted, and the nature of the fault. These processes allow operators to determine quickly and directly what the problem is/was and what remedial action is required, with a data trail available for later analysis or post-event review. Beam rate control will be hard wired into the Ms.+ ter Pattern Generator (MPG) and the Injector interlocks used to control the accelerator, so that the machine can be shut down if the expected rates are not properly executed. Failures of sensors or communications failures in sensor processors are treated as if the associated device or included devices where in a worst case failure mode, and appropriate action is taken. HARDWARE IMPLEMENTATION The new system will be implemented as a loosely coupled element of the SLC control system, with common facilities on the CAMAC side, new elements built into VME systems, and integrated SLC user interface and applications facilities. As shown in Fig. 1, the system will