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Reliability block diagram templates

RBD — Potable Water Pumping Station

Annual availability of a district pumping station with a two-of-three duty pump set, showing the 11 kV incomer as the weakest block on site and the rising main as an unavoidable series element.

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District pumping station — raw water to service reservoirMission 8 760 h · 1.00 yr · 11 blocks · 3 redundant arrangements · R 0.093326parallel · R 0.22117411 kV incomerR 0.185516 · A 0.99904Standby diesel gensetR 0.043780 · A 0.99361Motor control centreR 0.960964 · A 0.99996parallel · R 0.964559Variable speed drive AR 0.811743 · A 0.99986Variable speed drive BR 0.811743 · A 0.999862 of 3 · R 0.552234Duty pump 1R 0.534879 · A 0.99829Duty pump 2R 0.534879 · A 0.99829Duty pump 3R 0.534879 · A 0.99829Surge vesselR 0.952499 · A 0.99980Rising main to reservoirR 0.990314 · A 0.99981Telemetry outstationR 0.873918 · A 0.99994System reliability0.093326Unreliability0.9067System MTTF4 343 h · 181 dAvailability0.999501Reliability importance — Birnbaum ∂R/∂Rᵢ, with criticality share111 kV incomer0.403482crit 36%2Standby diesel genset0.343676crit 36%3Telemetry outstation0.106790crit 1.49%4Surge vessel0.097980crit 0.51%5Motor control centre0.097117crit 0.42%6Rising main to reservoir0.094239crit 0.10%7Duty pump 10.084087crit 4.31%8Duty pump 20.084087crit 4.31%+3 more blocks not shownIdle redundancy: Standby diesel genset in the parallel group is not buying anything — take it out and the group itself is only 4.6% more likely to fail, and the system 1.50e-2 less reliable. That is redundancy you are paying to maintain and are not being paid for.…Weakest link: 11 kV incomer — R 0.185516, Birnbaum 0.403482, 36% of system failure. Improving this one block moves the system number further than improving any other.

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title "District pumping station — raw water to service reservoir"
mission 8760h

# Repair times are what they actually are on this site: a pump swap is a
# day, a rising main burst is a road closure and a week of reinstatement.
block mains     "11 kV incomer"            mtbf: 5200h    mttr: 5h
block genset    "Standby diesel genset"    mtbf: 2800h    mttr: 18h
block mcc       "Motor control centre"     mtbf: 220000h  mttr: 8h
block pump1     "Duty pump 1"              mtbf: 14000h   mttr: 24h
block pump2     "Duty pump 2"              mtbf: 14000h   mttr: 24h
block pump3     "Duty pump 3"              mtbf: 14000h   mttr: 24h
block vsdA      "Variable speed drive A"   mtbf: 42000h   mttr: 6h
block vsdB      "Variable speed drive B"   mtbf: 42000h   mttr: 6h
block surge     "Surge vessel"             mtbf: 180000h  mttr: 36h
block main      "Rising main to reservoir" mtbf: 900000h  mttr: 168h
block telemetry "Telemetry outstation"     mtbf: 65000h   mttr: 4h

series {
  parallel { mains; genset }
  mcc
  parallel { vsdA; vsdB }
  kofn 2 of 3 { pump1; pump2; pump3 }
  surge
  main
  telemetry
}