Vegard Joa Moseng BI - BL Student meeting Reliability analysis summary for the BLEDP

 «SYSTEM ARCHITECTURE FOR MEASURING AND MONITORING BEAM LOSSES IN THE INJECTOR COMPLEX AT CERN» - C. Zamantzas, M. Alsdorf, B. Dehning, S. Jackson, M. Kwiatkowski, W. Vigano, BLEDP:  Function  BLEDP: Beam Loss Electronics Double Polarity  Acquisition module (card) is responsible for acquiring the input signal from the monitors with a dynamic range between 10pA and 200mA. This is done with the use of two measuring methods; FDFC which measures between 10pA and 30mA, and DADC which measures the signal directly in the 20.3uA to 200mA bracket.  Which bracket used is controlled by the FPGA based on the previous measurements. The FPGA is also responsible for doing most of the control operations in the card.  It is protected by circuit breakers and have it’s own power supply block for creating various needed voltages, locally.  It also has some diagnostics tools, such as humidity & temperature sensors.

Criticality  The Beam Loss Electronics Acquisition Crate (BLEAC) and the higher tier system is completely dependant on the continued correct operation of each BLEDP card in order for the beam loss protection system to function within the safety integrity levels set. This means that any failure in the BLEDP card that causes one of the 8 inputs for beam loss monitors to malfunction, will cause a false dump.  It is therefore very important to remove any potential blind failures. Detection  Detection of an malfunctioned BLEDP will typically be indicated in either failing the start up algorithm, or that the output values are obviously erroneous thanks to, for example, a dead ADC, no 5V to part of the card, loss of an input in a comparator and so on. This is evaluated for each separate failure mode for all the components in the BLEDP (see FMEA). Integration in the system

The schematic block arrangement  To simplify the analyses and to make it easier for the readers to identify important information, the report is constructed in blocks rather than components. For the blocks, the important failure modes for the individual components have been added to make sure all components have been evaluated and that the crucial information is preserved in the report.  Note: Each failure mode listed are in many cases a group failure mode for each identical component.  The circuit blocks are : 1.Circuit breaker 2.Input monitor 3.ADC channel 4.Filters and protection 5.Power supply 6.Connectors 7.Relay and Calibration 8.Misc (Temp, humidity etc) 9.FPGA The total number of failure modes are: 639 Failures modes with false dump: 561 Failure modes for maintenance: 78 Failure modes with blind failures: 0 Block system

MTTF:  The value is for a single BLEDP:  Failure rate per BLEDP: 1.106E-05  MTTF in hours: 9.043E+04  MTTF in years: 10.3 Number of different component blocks: 326 Number of different parameters: 4496 Risk Priority Number (SxOxD): 4094 Highest RPN possible (worst case): Lowest possible RPN: 639 Severity ranking  1. No effect: Non-critical failure such as filtering.  2. Maintenance: Failure in redundant components and other failures that allow for continued operation but should be fixed as soon as possible.  3. False dump: Failures that causes loss of critical functionality and/or safety, will cause the system to abort (dump the beam).  4. Blind failure: Failures where you are unable to detect erroneous information, or where you have no protection when you expect to have. Reliability analysis

Comments There are no Blind Failures that are not detectable within the same run by either the FPGA, connectivity check, erroneous COUNT value or an erroneous combination of COUNT values and ADC values (combination algorithm). Statistical inference for failure rate based on a conservative estimate shows a failure every 10 years. The real number is most likely less frequent than this indicates. The most likely components to fail are the voltage converters in the power supply block, which means a full BLEDP shutdown. RPN numbers are considered to be good - only about 20% of worst case.