1. RISK, QUALITY AND RELIABILITY – RQR ‘07
September 20-21, 2007
Technical University of Ostrava, Czech Republic
Components redundancy
in power and propulsion systems
installed onboard platform supply vessels
Dr inż. Leszek Chybowski
Prof. dr hab. inż. Zbigniew Matuszak
Mgr inż. Paweł Pełka

2. Minutes of presentation
Dynamic positioning (DP) systems classification
Platform supply vessels characteristics
Power and propulsion plants characteristics
Propulsion and power plants components redundancy
Final conclusion

3. Dynamic Positioning Class 1 (IMO MSC/Circ.645)
(A. J. SØRENSEN 2004)
Class 1 – loss of position (drifting off a given position and/or heading due to a DP system failure) may occur in the event of a single fault.

4. Dynamic Positioning Class 2 (IMO MSC/Circ.645)
(A. J. SØRENSEN 2004)
Class 2 – loss of position (drifting off a given position and/or heading due to a DP system failure) should not occur from a single fault of an active component or system such as generators, thruster, switchboards, remote controlled valves etc. But may occur after failure of a passive component such as cables, pipes, manual valves etc.

5. Dynamic Positioning Class 3 (IMO MSC/Circ.645)
(A. J. SØRENSEN 2004)
Class 3 – loss of position (drifting off a given position and/or heading due to a DP system failure) should not occur from any single failure including a completely burnt fire sub-division (e.g one of the power plants) or flooded watertight engine room compartment. Single faults also include single inadvertent act by any person on board the DP vessel.

6. Analysed vessels characteristics
Vessel of
UT 755 Design
UT 755 L Design
Main Particulars
LOA
LPP
Breadth Moulded
Depth Main Deck
Min Draught
Max Draught
DWT (max draught)
GRT
Net Tonnage
67,0 m
61,8 m
16,0 m
7,00 m
4,80 m
6,00 m
3000 t
2237 t
951 t
71,9 m
66,8 m
3,80 m
5,83 m
3084 t
2401 t
1069 t
Performance
Max speed
Fuel consumption
per day
14, 7 knots
Sailing: 18 14,7 knots
Standby: 4 t
In port: 1 t
14,2 knots
Sailing: knots
Machinery and
Propulsion
Main Engines
Auxiliary Engines
Emergency Generators
Shaft Generators
Main Propellers
Tunnel Bow Thrusters
Azimuth Bow Thrusters
Tunnel Stern Thrusters
Rudders
2 x Rolls-Royce Bergen, 5450 BHP
2 x 250 kW, 450 V, 60 Hz
1 x 48 kW, 450 V,
60 Hz
2 x 1600 kVA, V, 60 Hz
2 x CPP
1 x 800 BHP
2 x HighLift
2 x 320 kW, 450 V, 60 Hz
1 x 65 kW, 450 V,
2 x 800 BHP
N/A
Dynamic Positioning
DP system
DP References
Joystick
DP II – Kongsberg Simrad SDP21
2 x DGPS, 1 x Fan Beam, 1 x IALA Land Station
Fitted
2 x DGPS
1 x Fan Beam,

7. Power and propulsion plants configuration
UT 755 hull design
UT 755 L hull design

8. Redundancy in different DP classes
z(X,t) - complex number plane position for system X is:
where: p(X, t) - number of basic components
r(X, t) - number of standby components
i - imaginary unit
For a given moment of time t≥0 the total number
of components J(X,t) in the system X equals:
where: J(X,0) - size of the system X at t=0
JREST - number of components of the system X that have been failed till the time t.

9. Components redundancy in power and propulsion plant systems
ES1-1 – DP control unit
ES1-2 – DP supervision station
ES1-3 – manual control system
ES2-1 – main generator sets
ES2-2 – main switchboard
ES2-3 – gensets auxiliary systems
ES2-4 – mains switchboard buses
ES3-1 – ship’s main propulsion unit
ES3-2 – main propulsion rudder
ES4-1 – uninterrupted power supply
ES4-2 – battery set
ES4-3 – emergency power plant
ES5-1 – gyrocompass
ES5-2 – anemometer

10. Reliability calculation based on redundancy model
For the subsystem X with a threshold k-out-of-n structure composed
of identical components EX the system reliability is:
For the threshold structure k-out-of-n composed of components
E1, E2,…En with various reliability characteristics system reliability is:

11. Reliability calculation for DP thrusters
(for exponentional failures distribution and generic data)

12. Final conclusion
Component redundancy model allows to compare different redundancy classes (DP Classes)
Component redundancy model allows to compare different systems in same redundancy class
Component redundancy model allows to number of transformations and particular measures estimation
There is possibility of application of redundancy model for reliability estimation

13. Thank you for attention