TS-123
Some Considerations on Dependability Models of Redundant Power Systems on Board due to the Marine Field Data in Japan
Takeshi HASHIMOTO*, Hachiro KIDO**, Shinya HIDAKA*, Nobuo KIRIYA***
ABSTRACT
This paper describes the models of redundant system and dependability (reliability and maintainability with suportability) of power systems which are redundant engine sets with multi-cylinders for propulisive primemover and power generating station of ships, and their running data and designing and manufacturing ones.
As the some results of analyses it was obtained that the more safety degree due to the more paralell redunduncy of systems could be demonstrated by both the theoretical models and some statistical evaluation indices but on the other hand the harder man-power degree due to the more redundant systems could be also done by the kinds of two investigated data. They are more than 11000 field data (the Data Base of JSRIC; Ship Reliability Investigation Committee in Japan) submitted by 224 ships during 15 years 1982 〜 1997 and the 661 ones done by the 3rd. Technical Committee of Machinery of MESJ (the Marine Engineering Society in Japan) during 1997 〜 1999.
According to the surveyed on 270 ships with 661 generating sets installed during 1995 〜 1997 it was cleared that the avarage number of generating sets was estimated to be 2.90 [sets/ship] with the range of them was between 2 and 5 [sets/vessel], and that the range of number of cylinders per a generating set is 3, 5, 6, 8[cyl/set].
Analysing, the JSRIC Database during more than 7 millions propelling hours four kinds of evaluation indices (failure rate λ, average man-hour mh, manning index MI and average delayed time Td) were obtained with respect to all the failures and emergency ones which were 11,700 and 1,700 occurrences respectively. The three indices λ,mh and MI can formulate the equation of MI=λ×mh, then λi and λ di (all the failures and emergency ones) were between 0.2 〜 1.5 and 0.02 〜 0.9 [ooc./1000Hr] ,mhi and mhdi between 4 〜 14 and 9 〜 27[MH/ooc.] and MIi and MIdi between 2 〜 15 and 0.5 〜 15 [MH/1000Hr] respctively.
The tendency of λi could be confirmed by not only the analysed results due to lots of field data but also the redundant model for keeping the safety sea-going, but the ratios of mhdi to mhi was between 1.5 〜 3 but MIdi to MIi was between 0.3 〜 15.
key words; redundant powering system, diesel engine, marine field data, dependability, reliabilty and maintainability
1. INTRODUCTION
In order to keep the safty of sea-going all the warships, passengers boats and ferry boats used to have parallel engines and/or twin propellers. It is well known that a redundant system is always used in the vital auxilialy machineries like a stering system and generating power station on board by the rules of Classification but it is not well known that they do not always require the redundancy for main propulsive system.
Furtheremore there is no-doubt that the redundant concepts and system have clearly some merits and advantages, however does little evidence of running results, and besides it is not well known that the more redundant system needs the more man-power work for isolated crew on board from land-relief.
* Kobe University of Mercantile Marine
5-1-1 Higashinada-ku, Kobe, 658-007, Japan
Phone & Fax; 81-78-431-6280
E-mail; t-hashi@cc.kshosen.ac.jp
** Marine Technical College,
12-24 Nishikura-cho, Ashiya, 659-0026, Japan
*** Ship Research Institute of MOT
6-8-1, Shinkawa, Mitaka, 181-0004, Japan
