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Reliability block diagram templates

RBD — Offshore Wind Turbine Drivetrain

Annual reliability and availability of an offshore turbine drivetrain, where the 2-of-3 pitch group and the array cable's 60-day repair time pull the numbers in opposite directions.

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Offshore wind turbine drivetrainMission 8 760 h · 1.00 yr · 10 blocks · 1 redundant arrangement · R 0.161671Rotor blades and bearingsR 0.772868 · A 0.997182 of 3 · R 0.730362Pitch actuator, blade AR 0.658927 · A 0.99829Pitch actuator, blade BR 0.658927 · A 0.99829Pitch actuator, blade CR 0.658927 · A 0.99829GearboxR 0.864158 · A 0.98814GeneratorR 0.833185 · A 0.99305Full-scale power converterR 0.534879 · A 0.99829Yaw drive systemR 0.803322 · A 0.99880Nacelle transformerR 0.934836 · A 0.99871Array cable to substationR 0.990314 · A 0.99840System reliability0.161671Unreliability0.8383System MTTF4 871 h · 203 dAvailability0.972841Reliability importance — Birnbaum ∂R/∂Rᵢ, with criticality share1Full-scale power converter0.302256crit 17%2Rotor blades and bearings0.209183crit 5.67%3Yaw drive system0.201253crit 4.72%4Generator0.194039crit 3.86%5Gearbox0.187085crit 3.03%6Nacelle transformer0.172940crit 1.34%7Array cable to substation0.163252crit 0.19%8Pitch actuator, blade A0.099496crit 4.05%+2 more blocks not shownWeakest link: Full-scale power converter — R 0.534879, Birnbaum 0.302256, 17% of system failure. Improving this one block moves the system number further than improving any other.Redundancy check: removing any one of the 3 branches makes its own group measurably more likely to fail — the least of them by 110%. Every one of them is earning its place.

Make it your own.

title "Offshore wind turbine drivetrain"
mission 8760h

# Offshore MTTRs are weather windows, not spanner time: a gearbox exchange
# needs a jack-up vessel, so 720 h is a realistic mean downtime.
block blade   "Rotor blades and bearings"  mtbf: 34000h   mttr: 96h
block pitchA  "Pitch actuator, blade A"    mtbf: 21000h   mttr: 36h
block pitchB  "Pitch actuator, blade B"    mtbf: 21000h   mttr: 36h
block pitchC  "Pitch actuator, blade C"    mtbf: 21000h   mttr: 36h
block gearbox "Gearbox"                    mtbf: 60000h   mttr: 720h
block gen     "Generator"                  mtbf: 48000h   mttr: 336h
block conv    "Full-scale power converter" mtbf: 14000h   mttr: 24h
block yaw     "Yaw drive system"           mtbf: 40000h   mttr: 48h
block trafo   "Nacelle transformer"        mtbf: 130000h  mttr: 168h
block cable   "Array cable to substation"  mtbf: 900000h  mttr: 1440h

series {
  blade
  kofn 2 of 3 { pitchA; pitchB; pitchC }
  gearbox
  gen
  conv
  yaw
  trafo
  cable
}