Skip to content
flowss
Start freeChecking your session
Reliability block diagram templates

RBD — Data-Centre Power Train

Utility feed backed by a cold-standby generator pair, 2N UPS strings and 2-of-3 PDUs, computing annual system reliability, MTTF and availability for the rack busway.

Reliability block diagramArchitectureReliability block diagram syntax docs
Template previewReliability block diagram
Concurrently maintainable data-centre power trainMission 8 760 h · 1.00 yr · 10 blocks · 4 redundant arrangements · R 0.435381parallel · R 0.443257Utility 11 kV feedR 0.130392 · A 0.99907Automatic transfer switchR 0.952499 · A 0.99997cold standby · switch 0.995 · R 0.377719Diesel generator AR 0.122163 · A 0.99713Diesel generator BR 0.122163 · A 0.99713parallel · R 0.995044UPS string AR 0.929601 · A 0.99997UPS string BR 0.929601 · A 0.999972 of 3 · R 0.996780PDU 1R 0.966869 · A 0.99999PDU 2R 0.966869 · A 0.99999PDU 3R 0.966869 · A 0.99999Busway to rackR 0.990314 · A 0.99999System reliability0.435381Unreliability0.5646System MTTF9 068 h · 1.04 yrAvailability0.999991Reliability importance — Birnbaum ∂R/∂Rᵢ, with criticality share1Diesel generator A0.714589crit 90%2Diesel generator B0.710623crit 89%3Utility 11 kV feed0.628848crit 97%4Busway to rack0.439640crit 0.75%5Automatic transfer switch0.322632crit 2.71%6UPS string A0.030803crit 0.38%7UPS string B0.030803crit 0.38%8PDU 10.027984crit 0.16%+2 more blocks not shownWeakest link: Diesel generator A — R 0.122163, Birnbaum 0.714589, 90% of system failure. Improving this one block moves the system number further than improving any other.Redundancy check: removing any one of the 8 branches makes its own group measurably more likely to fail — the least of them by 15%. Every one of them is earning its place.

Make it your own.

title "Concurrently maintainable data-centre power train"
mission 8760h

# The utility feed is by far the weakest element — a few outages a year is
# normal, which is exactly why the generator path exists.
block grid   "Utility 11 kV feed"        mtbf: 4300h    mttr: 4h
block ats    "Automatic transfer switch" mtbf: 180000h  mttr: 6h
block dgA    "Diesel generator A"        rate: 2.4e-4 /h  mttr: 12h
block dgB    "Diesel generator B"        rate: 2.4e-4 /h  mttr: 12h
block upsA   "UPS string A"              mtbf: 120000h  mttr: 4h
block upsB   "UPS string B"              mtbf: 120000h  mttr: 4h
block pdu1   "PDU 1"                     mtbf: 260000h  mttr: 3h
block pdu2   "PDU 2"                     mtbf: 260000h  mttr: 3h
block pdu3   "PDU 3"                     mtbf: 260000h  mttr: 3h
block busway "Busway to rack"            mtbf: 900000h  mttr: 8h

series {
  parallel {
    grid
    series { ats; standby cold { primary: dgA; spare: dgB; switch: 0.995 } }
  }
  parallel { upsA; upsB }
  kofn 2 of 3 { pdu1; pdu2; pdu3 }
  busway
}