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Student meeting 10.06.2013 Reliability analysis of the local power supply in the BLEDP. Vegard Joa Moseng BI - BL. From «The new BLM system for the injector complex» BI DAY 2012 – William Viganò. The circuit:. Function. About the power supply circuit.
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Student meeting 10.06.2013Reliability analysis of the local power supply in the BLEDP Vegard Joa Moseng BI - BL
From «The new BLM system for the injector complex» • BI DAY 2012 – William Viganò The circuit:
Function About the power supply circuit • Converts the 48V input to the needed supply voltages in the BLEDP. • Conversion is done by the two DC/DC converters. One produces the + -5V which is used by many of the IC’s on the card, and the other one produces the 3.3V which is also the source of the 2.5V and the 1.2V. • The 2.5V which is used for I/O , is made in two different brackets, one with more filtering, and the same applies for the 1.2V which supplies the FPGA.
Criticality Integration in the system • The criticality of the on board power supply circuit is obvious, as each of the voltages are vital for the operation of the BLEDP card. • The lack of 5V or 3.3V would mean many of the IC’s won’t work along with no conversion to 2.5V and 1.2V, and the lack of 2.5V will cause there to be no I/O functionality in the ADC (among other things). • The lack of 1.2V means the FPGA itself is shut down. Detection Detection will be easy because the whole BLEDP card will be dead.
The block arrangement Block system • 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 many times a group failure mode for each identical component. • The blocks are (FM = Failure modes – 48 in total): • 5V DC/DC block (8 FM) • +48V Input voltage block (13FM) • 3.3V DC/DC block (6 FM) • Voltage converter 3,3V to 2,5V block (6 FM) • Step down current mode converter block (15 FM)
MTTF: Reliability analysis • The value is for a single power supply circuit. • Failure rate (1x ): 2.852E-06 • MTTF in hours: 3.441E+5 • MTTF in years: ~40 years 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 .
Risk Priority Numbers Total: Severity = 144 Occurrence = 1 Detection = 1 RPN = (3x1x1)117 = 144
A total of 48 failure modes for random failures in the BLEDP power supply circuit will cause a failure that will compromise the BLEDP card by affecting one of the output voltages negatively. However, the individual probability of the failures are so low that they are considered highly unlikely. Satisfactory detection is also present due to the impact of the failure modes on the system. Given the overall low probability and reliability focused design, no special action is warranted. Comments