Oper Routines

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    9711 PLANT OPERATION ROUTINES

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    1. PLANT OPERATION ROUTINES

    8A103/JC

    9711

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    1.1. OP ER ATION AND MAINTE NANCEO F T H E D IE SE L P O WE R P L AN T

    1.1.1. Introduction

    Setting up the operation of a power plant includes management of several areas,

    of which the Operation and Maintenance are mostly recognised. All the areas to-

    gether will form a Power Plant Management System. Managing a Diesel Plant

    requires the knowledge about means and methods to achieve maximum availa-

    bility at lowest possible cost benefiting from the unique features a diesel plant

    can offer. Wrtsil Diesel has over the years collected and established useful in-

    formation of the Management of Diesel Power Plants.

    Fig. 1 Plant Management Areas

    Management of a power plant requires specific knowledge about all the areas

    presented in this circle. Of special interest is the Planned Maintenance System

    (PMS).

    In the following is a detailed overview of the means and methods which we con-

    sider a valuable assistance in the management of your power plant. The system

    described is manually controlled but is as such directly adaptable to the computer

    based system also available from Wrtsil Diesel. The computer system is called

    MAMA and its special features will be highlighted within { } in the text that fol-

    lows.

    {MAMA is sold as an optional feature of the plant documentation system}

    Personnelstaff

    Maintenance PMS

    Administration

    Operation andsupervisionMaterial

    administration

    Accounting

    economy

    DATABASEMAMA

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    1.1.2. Operational targets - Operational performance

    Power production is a ongoing competition between different methods and sys-

    tems of production. The losers are the less economical alternatives. The diesel

    plant is favoured due to its high fuel efficiency and flexibility, combined with

    high operational safety and possibilities to reduce pollution.

    The major target in power production is to utilise investments done at lowest pos-

    sible operating cost. The total economy is generally measured by its key number

    for overall efficiency.

    Safe power supply may be invaluable. Consequential damage due to power

    shortage or breakdown usually makes operational costs neglectable and it is

    therefore of prime interest to maintain high availability of the plant. Safety is best

    characterised by a key number defined as availability.

    1.1.3. Major factors affecting availability

    Operation availability (Ao) is a primary measure of equipment readiness for a

    diesel power plant. It represents the expected percentage of time that the diesel

    plant or diesel engine will be ready to perform satisfactorily during normal oper-

    ation conditions. More precisely, this is the probability that the plant will be ca-

    pable of performing its specified function when started at any random point in

    time.

    Fig. 2

    Availability

    How often?Reliability

    MTBFMean time to failure

    How long?Stop time

    Effective repair timeMaintainability

    MTTRMean time to repair

    Waiting timeSupportability

    MWTMean waiting time

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    Fig. 3 Availability definitions.

    In this figure the standard method of estimating equipment availability is pre-

    sented. Operation and maintenance should target the major factors which reduce

    the plant up-time.

    1.1.4. Plant configuration

    One of the major reasons for selecting diesel engines as prime movers for power

    plants has always been the possibility to build up the capacity in steps according

    to need. The secondary effect of this is that in the multi-unit plant availability

    will be extremely high. Some general rules of the thumb in this respect are:

    1.Utilise variation in size

    of the generating sets so that a suitable number ofsets are in operation on any plant load.

    2. Utilise capacity to be able to operate at optimum efficiency as an averageover the load range, bearing in mind that a generating set typically have a

    optimum at loads from 70% to 90% of nominal.

    3. Utilise operation priority to be able to keep at least one set in maintenance

    1.1.5. Design and facilities

    Plant arrangements will play a role in availability by setting the standard of ac-cessibility both for daily measures as well as major maintenance and repair

    works. Pay special attention to the following:

    1. Ample space for performing inspections and maintenance. The more fre-quent the measure should be carried out the better the accessibility should be.

    2. Plan for work space (work shop preferably) and proper spare part stocks.

    3. Check that all major components may be withdrawn for major maintenanceand repair.

    4. Provide for over-all cleaning of both space and equipment.

    5. Place drains and vents in convenient locations. A well planned plant will be

    easier to maintain which again will improve the reliability.

    INFLUENCE ON AVAILABILITY

    A=MTBF

    MTBF + MTTR + MWT

    MTBF depend on: MTTR depend on: MWT depend on: preventive maintenance

    daily care parallel functions modification

    design, installation

    accessories

    systems, routines technical assistance training documentation spare part supply

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    1.1.6. Availability of spares and manpower

    Through case studies it is easy to find that the major factor in availability in re-

    ality is the waiting time, or in more general terms the plant supportability. In this

    area both the supplier and the operator may contribute in a favourable direction.

    Selecting the right spare parts for local stocking is a task worth spending sometime on, and in this respect supplier and operator have to co-operate. When se-

    lecting spare parts the following should be taken into account:

    1. What is the suppliers recommendation for wear parts.

    2. What is the suppliers recommendation for safety parts.

    3. What parts are available in local stocks.

    4. What are typical delivery times to site.Well trained staff and trimmed routines for administering the maintenance and

    spare part logistics are other important parts of the supportability factor. Local

    service by the supplier will ensure shortest possible availability of specialists

    when so required.

    {some of the major features of the MAMA system is its capability to predict

    spare part needs and in general to organise the spare part logistic system}

    1.1.7. Using RAM analysis for follow-up

    Availability follow up is a tool for the management of a diesel plant. Long term

    trends in availability would be good indicators for efficiency of the maintenance

    and failures in the logistics are easily detected. In order to make a proper follow

    up, a well administered machinery management system is required {WrtsilDiesel MAMA-system or similar}. In this system both scheduled and unsched-

    uled maintenance operations are registered. It is also important to register all fail-

    ures, at least those causing stops, so that a accurate failure rate may be calculated.

    The routines for proper log-keeping is presented later in this manual.

    The RAM (Reliability-Availability-Maintainability) analysing method present-

    ed below may basically be used for any single component or system in a plant

    and the results should be used to study the availability of the system of which the

    component is a part. Ultimately the analysis are extended to study the complete

    plant in its complexity of multi-units, load limitations and different levels of re-dundancy.

    When both the scheduled and the unscheduled maintenance are taken into the es-

    timate, the general formula will be:

    Ao =MTBF x k

    (MTBF x k) + MDTs + MDTu

    MTBF= T1 + T2 + T3 +... Tnn

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    This method to estimate availability is highly dependent on supportability in ac-

    tual operation environment.

    1.1.8. Major factors affecting efficiency

    1.1.8.1. Fuel consumption characteristics

    Fuel consumption for a diesel engine is usually given as a specific value for how

    many kilograms of fuel is required to produce one kilowatt hour (Specific Fuel

    Consumption (SFC), unit g/kWh). Note, that the SFC always is referred to the

    engine load. This value is the inverse of efficiency, i.e. when fuel consumption

    is at its lowest, efficiency is at its highest. fig 3. shows a typical fuel consumption

    curve for one engine. Applying this curve to a multi-unit plant will give a com-

    bined curve according to fig 4 . With the help of this curve the plant utilisationefficiency may be studied. Some general remarks:

    1. The plant is less efficient at very low loads.

    2. The diesel engine have a very broad (flat) high efficiency operating field.

    3. Efficiency decrease at peak loads.

    4. Optimum efficiency may sometimes be reached using engines of differentsize in the same plant.

    Fuel efficiency will also to some extent be influenced by the actual ambient con-

    ditions.

    Fig. 4 Specific Fuel Consumption curve, for one single unit.

    SFC for one unit follows this typical curve. The plant operator should observe

    the best operating field.

    50% Load 100%

    Bestarea

    Specificfue

    lconsumption

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    Fig. 5 Specific Fuel Consumption curve, for a multi-set installation

    By combining the characteristic consumption curves of several units a more orless favourable plant consumption may be achieved by selecting the start and

    stop of individual units.

    1.1.8.2. Equipment condition-maintenance

    The condition of some key components, specially in the fuel system, will have a

    strong influence on the engine efficiency. Efficient machinery is maintained

    when at least the following maintenance measures are properly carried out:

    1. Fuel nozzles are checked and changed if found that the atomisation character-istics are abnormal. Payback time for changing nozzles is counted in hours,

    not in years.

    2. Perform water cleaning of the turbo charger regularly, specially in plantsusing heavy fuels.

    3. Operating the engine at optimum loads will prevent fouling of the combus-tion spaces. If extensively run on low loads cleaning of the combustion

    spaces may be required more frequently than normally recommended.

    4. Right charge air temperature will guarantee best fuel consumption. Keep

    the cooling systems in good condition.

    Specific

    fuelconsumption

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    Usually time spent in maintenance is recovered many times through savings in

    fuel consumption.

    1.2. P OWE R P LANT OP E R ATIONALROUTINES

    1.2.1. A general presentation

    1.2.1.1. Organising staff

    After the operation being defined with regard to grade of automation and man-

    ning the management should go through a detailed study of what need to be done

    to get the plant operational. The result of this study should be well defined jobdescriptions and routines for all tasks to perform in the plant, and adequate train-

    ing should be done.

    A. SETTING OF OPERATIONAL GOALS

    B. ORGANISING PERSONNEL JOB DESCRIPTIONS

    ACTIVITY DESCRIPTIONS FOR ROUTINES

    C. ORGANISING DOCUMENTATION INSTRUCTION DOCUMENTATION

    LOG/REPORTING SYSTEM

    ORGANISING MAINTENANCE TOOLS

    ROUTINES

    D. ORGANISING SPARE PARTS LOGISTICS STOCKING

    PURCHASING

    Routines and instructions form the basis of power plant operation training, which

    should be an on-going activity in any power station.

    Documentation of the routines in a standardised way helps the management to

    train its staff and to keep to the routines agreed upon.

    {The Machinery Management System (MaMa) contains a Planned Maintenance

    program which will work according to the strategic decisions done by the man-

    agement. The MaMa system will here be the flexible tool to document and fol-

    low-up the progress of maintenance.}

    1.2.1.2. Working routines

    All power plants will have working routines, whether documented or not. Setting

    up the Power Plant Management System means that the routines will be well de-

    fined and that these routines also in the daily operation will be followed. In a

    power plant we may identify four different groups of routines:

    supervision routines, which are highly dependant on the grade of monitor-

    ing

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    maintenance routines, which are dependant on the maintenance strategy

    control routines, which are highly dependant on the grade of automation

    administrative routines, which are company specific.

    We will in the following concentrate on the Supervision and Maintenance rou-

    tines. Control routines are described in the user instructions and the Administra-tive routines are better dealt with in intercompany instructions.

    {the MaMa system also covers specific routines of Supervision and Maintenance

    but is extended with some administrative functions such as allocation of costs

    and budgeting}

    1.2.1.3. Reporting

    Just like plans and budgets are a link between the Strategic Management and the

    Tactical level of management, reporting is the necessary link between the Tacti-cal level (middle management) and the Operative level of staff. Reports are re-

    quired at all levels but for different purposes. The top management may require

    a brief monthly report giving actual figures of availability, efficiency and budg-

    ets, while maintenance staff will be better served by Maintenance plans and spare

    part availability reports.

    Fig. 6(Fig 5) Reporting chain

    The reporting chain is usually built in a few links, of which all links at all times

    must be intact.

    In reporting motivation of staff at all levels is of critical importance. The benefits

    of collecting data must be proved through the actual use of this data in the daily

    work. Data must be evaluated and used in a form which is easy to read and un-

    derstand i.e. calculated summaries and graphical presentations like in trend

    curves. Training of the power station staff in both administration and technical

    aspects of the plant operation is naturally very important from this point of view.

    Training must stress the need to react on abnormal data as early as possible in thereporting chain.

    DATA

    DATA

    DATA

    Sum

    Sum

    Sum

    REPORT MaMa Feedback

    DB

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    The reporting chain as presented above is divided into four steps of activities:

    Step-1, Data collection

    Information specifically needed to monitor performance of the plant is collected

    either through an automatic data logging system or through manual reports col-

    lecting data in forms. Standardised forms for daily, weekly and monthly report-ing is used. Data collection is part of the supervision routines and its frequency

    is defined in the respective form used.

    {the forms presented here are the reports that are used in connection with the

    MAMA system}

    Step-2, Reporting

    Data collected is presented in the following standardised reports:

    {when using the MAMA system this step means entering the defined informa-

    tion in order to give on-line access to the information later}

    Step-3, Data processing

    This is a step to evaluate and process the collected data for presentation in a suit-

    able form and discuss the results in formal meetings or daily routines.

    In our system the following process are recommended:

    operation priority list, either continuous or daily updating

    maintenance schedule, updated according to works performed

    weekly maintenance plan, weekly work plan for maintenance

    trend curves, selected data presented in trend curves

    {when using the MAMA system the basic data processing is automatically per-

    formed when entering data}

    Table 1:

    Report Frequency Reporting

    energy report daily daily

    machine operation log status change daily

    daily machine log hourly daily

    station log hourly daily

    power interruption log status change daily

    daily check list daily weekly

    plant attention report irregular daily

    maintenance report planned daily

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    Step-4, Feed-back reporting

    Feed-back reporting is the process of preparing special reports based on the data

    and information collected in the three previous steps. Our system suggest a few

    standard reports to be considered:

    statistical report, a detailed monthly summary of the key numbers of opera-tion (a typical report with explanations is attached herewith)

    station log summary

    machine log summary (individual status report for the generating set)

    The above reports are typical reports to the top management.

    {The real benefit from a MAMA system comes from feedback reporting. The

    system contains hundreds of reporting facilities of which the following are some

    of the most important ones:

    statistical reports, available in several levels

    efficiency report, selectable period

    maintenance plan over selectable number of weeks

    maintenance overview for selectable period

    maintenance reports at several interest levels

    stock inventory lists

    recommended purchases

    evolution of readings

    budget reports

    All the reports in MAMA are available any time and may be presented either on

    the screen or as printed reports}

    Forms and documentation of reportsHaving a Machinery Management System or not, organising the plant operation

    always means some forms will be required. Forms are designed to match the pre-

    viously described reporting chain. Introducing new routines and forms is always

    difficult task, it is therefore good to do a good homework and implement the right

    forms from the beginning.

    Badly designed forms will lower the motivation to use routines and systems.

    Good forms have usually been developed during a long period by the user them-

    selves. All the standard forms herein described are included in the Logbook file.

    The need for a good filing system will soon become necessary, however, it is not

    possible to give a definite suggestion for what files are required since the set upis very much depending on the people involved and the room to store each indi-

    vidual peace of information.

    A suitable filing system may be set up as follows:

    1. Machine logs, individual for each generating set (should have numberedpages)

    2. Station logs

    3. Energy reports

    4. Maintenance log, including daily checklist, Maintenance reports, Plant atten-

    tion reports, maintenance schedule and weekly maintenance plan5. Trend curves

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    {In this area the support of the Machinery Management System MAMA is re-

    markable, the system is fully integrated with the forms and may also print forms

    for daily use. Depending on the system configuration MAMA may also substi-

    tute paper reports since the information is available for the users on-line any time

    when needed}

    1.3. SUP E R VISION

    1.3.1. Supervision level

    Setting the optimum supervision level is critical both to efficiency and reliability.

    The trend today is towards higher degree of automation, we already talk about"intelligent engines". The grade of automation will increase with higher labour

    costs, however there are many factors to weigh into the decision of automation:

    1. Is skilled labour available to operate and maintain the automation systems

    2. Is the automation system proven to be reliable.

    3. Will the manufacturer have local support for the system.

    4. Is the system easy to learn and use, even in infrequent use.

    5. What is the typical use of the plant now and in the future. Generally speak-ing, in terms of monitoring and control the human can do more and many

    times also better than the system.

    Fig. 7 Supervision level, power plant

    MACHINE LOG

    STATION LOG

    SHIFT TAKE OVER

    DAILY CHECK

    OPERATION PRIORITY

    ENERGY READINGS

    STAND-BY ENGINE TEST

    ENGINE TEST (every 50h)

    Routinesperformed by the

    the plant staffHOURLY

    PERSHIFT

    DAILY

    WEEKLY

    MONTHLY

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    A recommended minimum supervision level is set in fig.6 The methods to per-

    form the supervision may however be very different depending on the grade of

    automation other staff related aspects.

    The actual supervision level is decided together with the manufacturer in an early

    stage of the project. The decisions are followed up by the planning of the Man-

    agement system and its subsequent training of staff.

    1.3.2. Specific routines of Supervision

    A routine is an activity performed according to a defined schedule following a

    route agreed upon and performing specified tasks in named stations. In the fol-

    lowing the routines of the recommended supervision level are described in detail:

    Operation Priority List (OPL)

    By means of the OPL the plant supervisor monitors and controls the operatinghours of the generating sets. This is a typical daily (morning) duty. The list

    should give present status of each generating set using standard definitions like

    "On SB", "In Maint." etc.. Operation priority can be selected one of three meth-

    ods:

    A. Constantly even operating hours

    B. Constantly offset operating hours

    C. Continuously diverting operating hours

    Machine Operation Log (MOL)

    This is the individual log for each generating set and it should be continuouslyupdated any time a change in its status occur. A change in status is considered

    any start or stop but also performing of maintenance on a stand by set must be

    recorded. As a minimum (e.g. for stand by sets) the status at 00.00 and 24.00

    shall be stated. The log is summarised and reported once per day.

    Note! The log must have numbered pages.

    Power Interruption Log (PIL)

    This is the log for the power production and the recording of possible disturbanc-

    es in either production or distribution of power to the consumers. The log is sum-marised and reported once per day.

    Daily Machine Log (DML)

    The recommended frequency is to perform a normal round-trip once per shift, al-

    though many stations perform these as frequent as every hour. What should be

    kept in mind is the purpose of the trip is firstly visually inspect the plant and sec-

    ondly to collect some specific data. From this point of view the correct frequency

    should be selected.

    One of the daily readings should be selected as a reference data. This time should

    preferably be selected during normal peak hours (e.g. noon ) and the data collect-ed from that round-trip will be used to enter into the trend curves. Transfer of

    data to the trend curves should be done daily and preferably in the morning.

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    Daily Station Log (DSL)

    The frequency of this log should preferably be the same as for the Daily machine

    logs. It is reported daily.

    Daily Check List (DCL)This list is a summary of the daily measures in the form of checks and mainte-

    nance tasks that should be performed by either the operators or the maintenance

    staff. The importance of this check should be stressed and it is recommendable

    that the station supervisor performs a daily double check according to this list.

    Daily Energy Report (DER)

    Energy readings are usually taken a given time of the day (typically midnight).

    They are recorded in the Energy report and the efficiency of the previous day

    may be calculated. It should be noted that this daily report seldom is very accu-

    rate, to get more reliable figures a much longer reporting period should be select-ed. (e.g. one month).

    Plant Attention Report (PAR)

    This report is designed to be used by the operators as well as maintenance staff.

    It serves as a reminder to perform rectification works (irregular work) and is is-

    sued immediately when a problem is detected. The Plant Attention report should

    be attended to in the daily maintenance or included in the weekly maintenance

    schedule.

    Trend monitoring curves (TMC)Selected parameters of the Daily Machine Log are transferred to graphs showing

    the daily development of the measured values. Values should be selected the

    same time every day and preferably from a period typically having relatively

    high loads.

    Stand By Test (SBT)

    Generating sets being on stand by for longer periods than one week should be test

    run according to prescribed procedures.

    Engine Test Run (ETR)Irrespective of the engine being in operation or on stand by it should be perform-

    ance tested either every 500 hours or at least once per month. This measure is

    also considered to be a maintenance operation and is therefore included in the

    maintenance schedule. This test run will be recorded in the Operating Data

    Record and the results should be compared to the official norm curves of the en-

    gine.

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    1.4. MAINTE NANCE

    1.4.1. Maintenance strategies

    The purpose of planned maintenance is to ensure the trouble free and economical

    service of the equipment in the plant. Since maintenance is causing costs, it is

    natural to try to minimise the work carried out. It has to be considered on one

    hand how often and how thoroughly should the maintenance be carried out, and

    on the other hand what kind of risks will be taken in case some of the measures

    were postponed or not carried out at all. Both the engine manufacturer and the

    owner of the power plant have to consider that question, the engine manufacturer

    when laying out the maintenance instructions and the power plant management

    when deciding when and what maintenance work should be done.

    In a power company, like in most other companies, we typically find three levelsof responsibility in the maintenance:

    A. The STRATEGIC level, setting the targets of maintenance. Important deci-sions regarding the resources, methods and goals of the plant are done at this

    level. Typical decisions may be to decide what part of the maintenance to do

    with own staff and what to subcontract. Signing of maintenance contracts are

    considered at this level.

    B. The TACTICAL level, which should be able to carry out plans according totargets set and in this process use information gained from the operative

    level.C. The OPERATIVE level, that should have the skills and instructions to

    carry out the daily tasks in the plant.

    Fig. 8 Organisation responsibility levels

    Different levels of staff plays their own role in the maintenance organisation. The

    Power Plant Management System will have to serve all the three levels.

    There are a lot of factors which affect the need of maintenance, all of which atleast the tactical level should be aware of:

    OPERA

    TIVE

    STRATE

    GIC

    TA

    CTICAL

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    1. The equipment features, especially in respect of reliability and serviceabil-ity.

    2. The engine load and annual running hours. There is a big difference innecessary service work between a diesel engine of a emergency set and an

    engine of a base load plant.

    3. The type of fuel. The maintenance cost when running on heavy fuels may besome ten percent higher than for using pure distillates, however, this fact

    does not offset the savings from using heavy fuel.

    4. Ambient conditions. High altitude and high ambient temperature will nothave any bigger negative influence if only the engines are de-rated corre-

    spondingly. The cleanness of the charge air is moreover important.

    5. Lub. oil quality and treatment. When running on heavy fuel, utmost atten-tion should be paid to the proper function of centrifuges and filters in the lub.

    oil system.

    6. Cooling water quality. The choice of cooling water system should be studied

    carefully at the planning stage of a power plant. Abnormal corrosion ordeposits in cooling water spaces of the engine may cause additional costs.

    1.4.2. Maintenance scheduling-condition monitoring

    As already mentioned, a recommended maintenance schedule is given in the in-

    struction manual. This recommendation is based on experience during normal

    operating condition, possibly taking into account the quality of fuel.

    Fig. 9 The principle of a maintenance schedule

    250 h

    500 h

    1000 h

    2000 h

    8000 h

    4000 h

    16000 h

    250 500 750 1000 1250 1500 1750 2000

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    In a Planned Maintenance schedule the operations are performed at regular inter-

    vals which means that the amount of work for each occasion may vary consider-

    ably.

    Note! The user is not allowed to change the maintenance intervals of the equip-

    ment during the warranty period without the consent of the manufacturer.

    The need for maintenance stated in this schedule is also based on the running

    records obtained from the engine under normal operation. Such operating data

    may be:

    exhaust temperatures

    max. firing pressures

    turbocharger speed

    charge air pressure and temperature

    fuel rack position of injection pumps

    pressure drop over charge air cooler

    pressure in the crank case

    The information given by these data is valuable and gives a good picture of the

    engine condition, provided that they really are evaluated by a trained person.

    This method of checking the state of the engine is normally referred to as engine

    testing for which standard report graphs are available.

    Other means of condition checking is to perform visual inspections on compo-

    nents, component condition evaluation. A general visual inspection, being it by

    means of endoscope or the bare eye, require a very experienced engineer with

    training especially for the inspection of modern bearings. Easier is the method ofmeasuring main components at specified and critical areas. For this purpose the

    manufacturer supplies standard forms.

    Today much more advanced systems are available. They are called condition

    monitoring systems and are usually monitoring a few but very important param-

    eters, like:

    main bearings

    cylinder liners and indirectly also the pistons

    exhaust valves

    When using that system, serious breakdowns can be prevented through an early

    alarm signal or automatic shut down in case of bearing overheating, piston sei-zure or leaky exhaust valves.

    The very latest technology in this field is the computer based diagnostic systems

    (Wrtsil Diesel FAKS, or similar) which are capable of supporting the operat-

    ing staff in their judgement of plant behaviour and thus detect signals of malfunc-

    tion in a very early stage. A diagnostic system is connected to a large number of

    measuring points which are scanned at intervals much more frequent than any

    human could ever do. Based on the huge amount of data the sc. expert system

    will continuous perform a diagnosis of the actual state of the equipment. Obviously the

    trend is to equip the machinery with these sophisticated monitoring systems and to base

    the need of maintenance to a greater extent on the systems.

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    1.4.3. Maintenance routines-quality of work

    It is an unfortunate fact that engine failures or serious breakdowns sometimes is

    experienced immediately after an engine overhaul. The reason is usually easily

    found - something was made wrongly during the overhaul. Some typical mis-

    takes are mentioned hereinafter:

    wrong judgement of bearing condition. A worn bearing may not do any

    harm as long as the bearing remains untouched, but if the same bearing is

    taken out of the engine and assembled again, the geometry of the bearing

    can be disturbed, resulting in a failure.

    important bolts are wrongly tightened

    engine components are wrongly reconditioned or assembled.

    Most of these mistakes could be avoided if the maintenance work were carried

    out by skilled enough engineers and staff.

    The management of a power plant should therefore consider to what extent the

    maintenance work should be carried out by the staff at the plant and for what

    measures the services of manufacturer should be used.

    This is a very important strategic decision and the manufacturer is nowadays pre-

    pared to extensive co-operation e.g. through maintenance agreements.

    1.4.4. Spare part logistics

    The engine manufacturer is often asked to give a recommendation for spare parts

    which should be kept on stock at a power plant. Before he does so, the base on

    which the recommendation is to be given, should be agreed upon. In the follow-

    ing some aspects:

    1. If the annual running hours were known, the minimum spare part stockcould be planned according to the maintenance schedule given in the instruc-

    tion manual.

    2. The consequences of an eventual failure of an engine component evaluated.

    Can it e.g. be accepted that the engine is out of service until spare parts havebeen supplied from the service station or from the manufacturer? The result

    of such a consideration may be that cheaper but essential safety parts should

    be kept in stock at site.

    3. The time needed for normal maintenance could be reduced if certain com-ponents immediately could be replaced by reconditioned ones in an

    exchange system. A complete set of injection valves, cylinder heads etc.

    could be of great advantage when trying to save time.

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    Fig. 10 Spare Part Stock Control

    For each article in stock a definite stock level should be defined, at the same time

    a decision for which part to stock must be done. This is an important factor of

    plant availability.

    The spare part logistics is to a great extent a co-operation between the plant, the

    local service station and the manufacturer.

    {the MAMA program includes all the required facilities for spare part logistics}

    1.4.5. Maintenance planning

    Since we now work according to the principle of preventive maintenance, this

    also means that we must be able to foresee (predict) the maintenance in advance.

    Maintenance planning is best done using a Maintenance Schedule as a tool. For

    more detail planning a Weekly Maintenance Plan will help to organise the work

    and in the day to day schedule we use a Daily Check List. These three tools shall

    work together as follows:

    1.4.5.1. Weekly Maintenance Plan

    This plan should be agreed upon mutually by Operation and Maintenance man-

    agement since it basically takes both sides into account:

    operation must allow a scheduled stop or advice when the stop best may be

    performed

    maintenance shall be able to estimate the time required for the stop based

    on available staff and spare parts

    The Weekly Maintenance plan is a summary of the work that is estimated to be

    done according to the Maintenance schedule, the Plant Attention and other irreg-

    ular work. It is good practice to do the WMP either in the beginning of the week

    or end of the previous week.

    {the MAMA system will automatically draw the Maintenance Plans}

    SAFETY STOCKAmountof

    work

    Point of re-ordering

    Time for delivery

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    1.4.5.2. Maintenance schedule

    Many types of maintenance schedules exist. The method we here introduce have

    the advantage of additionally also working as a planning tool. The schedule is

    used step by step in the following way:

    1. Each individual schedule is issued on the day and running hour that the jobwith the lowest period require. These are the Date and Hours which

    firstly are entered into the lines for Scheduled operating hours and dates".

    2. The jobs performed are recorded on their respective lines and signed off.

    3. Jobs are then scheduled starting from the date and hour given in (a)."Hours" is estimated using the lowest period as in this example:

    4. Hours for issuing the schedule is 3590 and the lowest period is 250 hours.The next time this job shall be performed is then at 3840 hours. If the esti-

    mated running hours per day is 22 hours this will mean that the next time to

    perform this job is eleven (11) days forward etc.

    5. The schedule is used for guidance and jobs should be performed within itslimits with a maximum deviation of 10%. Note, that a deviation from the

    plan should not change the schedule which could cause a reduction in the

    number of jobs performed.

    1.4.5.3. Daily Check List

    The DCL is issued every week and the routine checks that it contain shall be per-

    formed at a given time or according to a given schedule every day. It should also

    be given task for the plant supervisor to follow this work up by personal inspec-

    tions of the plant.

    1.5. Tr a in in g is a m u s t -Se t t in g u p t h et r a in i n g p la n

    Everything in operation and maintenance is working towards best possible total

    economy. Obviously training must start from this understanding, everything in

    training should support this effort.

    Finally, it has to be emphasised that training of the staff at the power plant is im-

    portant not only in respect of maintenance work, but also in order to create a bet-

    ter understanding of engine behaviour and condition. The engine manufacturer

    is obliged to provide training courses of various levels either at the factory, at lo-

    cal service stations or at site.