TSU CONS Reliability Meeting - 5

Present: M. Blaszkiewicz, L. Felsberger, N. Voumard, P. Van Trapen

Minutes

The purpose of the meeting was to review progress and discuss findings of the reliability study after the failure rate prediction and failure mode apportionment steps and before the end-effects assignment.

Key Discussion Points

• Detailed methodology and assumptions for failure rate prediction
• Statistical analysis and findings for TSU and TSU RTM boards
• Importance of accurate failure mode apportionment and end-effects assignment
• Strategies to improve reliability and reduce failure rates through ongoing analysis

Study Workflow

Steps followed in BISv2 reliability analyses

1. Estimation of failure likelihoods for components and subsystems
2. Identification of failure modes with assigned probabilities
3. Establishing failure end-effect probabilities for risk matrix comparison

Failure Rate Prediction

A recap of assumptions and parameters used in the first step of the study, followed by statistics and estimations - outcomes. 

The TSU Board: 2618 FIT (excluding rotary switches), TSU RTM Board: 299 FIT. 30 capacitors have no applied voltage read by the script, therefore a default value is used for them instead (to be followed up). Global assumptions were confirmed, with a modification to the duty cycle which was suggested to be set to 3-4, operating temperature to 50 for PSU and FPGA, as well as humidity to low (as is the case of the LHC).

The high failure rate indicated by the 217Plus standard for rotary swiches is somewhat confirmed by the experience (not in operation though) - therefore, this subject can be further explored if the end-effects show relevant criticality of their failures. They are used to set the delay between BRF and Delayed BRF and abort gap keeper - TSU in SBDS does reading when power on, and keep when in operation

Conclusions and Recommendations

The FMECA end-effects assignment should consider effects on the level of two TSU boards, exculding the CIBDS. 

Next steps are laregly to establish criticality of rotary switch failures (as both theory and practice shows potential problems). The next step is the end-effects assignment, for which we will send an FMECA table to NV as soon as possible, extending it with columns specifying pins connected to the capacitors.

Actions

1. Expand the FMECA tables to contain information on capacitors' pins.
2. Share the FMECA table with NV.
3. Providing support for the end-effects assignment step.