me002 basic mechanics for non mechanical trades pr inst

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SRI LANKA INSTITUTE of ADVANCED TECHNOLOGICAL EDUCATION

Training Unit

Electrical MaintenanceTheory

No: MS 004

INDUSTRIETECHNIKINDUSTRIETECHNIK

Automotive Engineering

Instructor Manual

Electrical and Electronic

Engineering

Instructor Manual


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List of Contents Page

Introduction 3

1. Definition 41.1. Breakdown Maintenance 51.2. Preventive Maintenance 51.3 Condition-Based Maintenance 62. Maintenance Philosophies 72.1 No Maintenance 82.2 Breakdown Maintenance 92.3 Preventive / Planned Maintenance 102.4 Predictive / Condition Based Maintenance 113. Goals Of Maintenance 143.1 General 154. The Position Of Maintenance Within A Company 165. Current Practical Situation Of Maintenance Management 176. Increasing Complexity Of Maintenance Services 187. Maintenance Strategy 197.1 Increasingly Stringent Safety Requirements 207.2 Stricter Environmental Regulations 207.3 Maintenance Orientated Design 207.4 Relative Increase In Knowledge 217.5 Shrinkage Of Time-Intervals 21

7.6 Shorter Utilization Time Of Systems, Process And Programs 217.7 Shorter Innovation Period 217.8 Manifold Combinations Possible 228. What Is Inspection (Condition Monitoring) 239. The Significance Of The Application Of Inspection Systems 2410. Reasons For Machinery Failure 2511. Total Cost Of Maintenance 2612. Maintenance Activities


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INTRODUCTION

For the most part, isn't maintenance still as a necessary evil or as an extension ofproduction? Don't maintenance departments hold a relatively high degree ofresponsibility yet have very little influence when important decisions are made?

These common attitudes will hardly enable companies to meet the challengesconfronting them in the future.

There are manifold reasons why maintenance in practice is not usually accorded theimportance it deserves. These range from insufficient knowledge of this specializeddiscipline to a lack of appreciation for maintenance activities and all the way tofailure to recognize the close ties between production and maintenance.

It is important that company management will acknowledge the steadily risingimportance of maintenance. Maintenance will in fact become a decisive factor inproduction.

More and more industries are employing condition-monitoring programs in theirmaintenance strategies to increase plant equipment availability.

This presentation will describe the difference between condition monitoring and othermaintenance philosophies and their development over the years.


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1.1 DEFINITION

The maintenance strategy is an object-related procedure, which specifies individualmaintenance activities, i.e. content, method and scope, to be carried out atpredefined intervals. If this procedure is defined by optimalization criteria then onerefers to an optimal maintenance strategy.

A review of the maintenance strategy over the course of time should begin before1970. At that time, the area maintenance foreman was the dominant figure in the

maintenance world.

He determined when and how a repair would be carried out based purely on hisown personal experience - normally after the damage had occurred - and alsodecided where and when plant improvements would be carried out.

Costs were irrelevant, budgeting and cost control was done but only in a very limitedway.

Many companies still follow the strategies of the 50's and 80 's for the most part,so-called unplanned or breakdown maintenance.


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1.1 Breakdown Maintenance

Using this method Planning costs are fairly low. However, work can only be planned afterdamage has occurred.

This method can resultin:

0 high breakdown rate0 considerable amount of consequential damage0 longer preparation time0 time-consuming spare parts ordering procedures0 inefficient use of resources (personnel, material, time, funds)

Naturally, this procedure is still worthwhile for some components but the percentageof breakdown maintenance should be very small

Companies, which recognized that this strategy was not efficient enough for theirplants moved one step further, to preventive maintenance.

1.2 Preventive Maintenance

A method, which was first applied in the airline industry, is based on regularreplacement or repair of parts based on experience, without taking the actualcondition of the part into consideration.

This had the following advantages:

0 reduction of the breakdown rate0 accurate planning of the maintenance activitiesO precise control of resources0 lower damage costs0 increased safety

However, there were still some disadvantages to be considered:

O higher consumption and costs of spare parts0 Inefficient use of spare parts and personnel due to too frequent replacements

and repairs

The exclusive use of this method like it was the case in the 1970s was thus veryexpensive for most companies, but preventive maintenance nowadays is still anecessity for equipment, which should provide 100% availability and safety.


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Finally, due to cost considerations, further development led to condition-basedmaintenance.


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1.3 Condit ion-based Maintenance

Maintenance activities were enhanced to include constant monitoring of equipmentand parts. The results of this monitoring are decisive factors in when a part shouldbe replaced or repaired.

The advantages and this method are obvious:

O selective planning and resource utilizationO low spare part costsO constant, up-to-date knowledge of the equipment condition

These and other advantages clearly justify additional personnel costs for inspectionand increased planning.


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2. Maintenance Philosophies

The following diagrams show the effect of different maintenance philosophies on

equipment life.

A . . . . . no maintenance

B . . . . . breakdown or unplanned maintenance

C . . . . . preventive or planned maintenance

D . . . . . predictive or condition based

maintenance


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2.1 A. NO MAINTENANCE


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2.2 B. BREAKDOWN MAINTENANCE


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2.3 C.PREVENTIVE / PLANNED MAINTENANCE


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2.4 D. PREDICTIVE / CONDITION BASED MAINTENANCE


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Due to the fact that the "no maintenance" strategy as such no longer exists, three

basic equipment maintenance philosophies remain to be applied.

Breakdown Maintenance (run to failure) "Running till breakdown occurs". This

strategy will be followed if breakdown costs are less than costs of other

strategies.

Preventive Maintenance

"Changing parts periodically". This strategy will be followed if condition monitoring

is impossible or uneconomic or breakdown costs are higher than replacement

costs.

Predictive Maintenance (condition monitoring) 'Planned replacements prior to

breakdown expected due to results of regular checks".


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Most machinery failures are predictive; therefore a good, well-selected monitoringprogram provides the basic tool for predictive maintenance.


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GOALS OF MAINTENANCE


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GENERAL

The corporate function of the maintenance department is to ensure that thetechnical facilities are in working order. Maintenance economy is defined by thegoal of minimizing the overall costs arising from the direct and indirect maintenance

costs. This goal is achieved by investing in information systems and the resultingplan ability. Today, of course, one is seldom in a position to apply this theoreticalknowledge as a management tool in practice. The reason for this is the difficultadditional collection and preparation of the respective data, which would have to beextensive enough to demonstrate an empirical relationship between the individualfactors with sufficient accuracy.

Progress towards optimization can be achieved, however, through continualcomparison of the costs of in-house services as well as the prices of contractedservices and the corresponding market trends. By suitably depicting the cost ofmaintenance activities, it is possible to determine the optimum capacity of thein-house maintenance department as well as the share of externally contractedservices.

Before the corporate objective for the plant maintenance sector is defined, anumber of maximization and minimization targets are listed, which are of highestpriority and are frequently cited in maintenance literature and practice.

Several frequently-mentioned targets are:

o cost minimizationo maximum plant availabilityo maximization of reliabilityo economical plant maintenance

o maximization of service life by preserving the value of fixed assets.

In addition to these individual targets, certain target-groups are also indicated, suchas:

0 optimization of profit0 optimization of service life0 optimization of maintenance costso ratio of preventive maintenance cost to cost of expected damage is

reasonable

From an economic viewpoint, the partial goals are always derived from theoverriding corporate goal of profit maximization and can be summarized into twoprimary goals of maintenance:

Optimization of Plant Availability


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Minimization of the Total Cost ofMaintenance


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4. THE POSITION OF MAINTENANCE WITHIN A COMPANY

As a result of technical developments and cost trends the significance ofmaintenance and the value attributed to ft is being increasingly recognized andacknowledged. Solutions have been developed by companies themselves, as well

as by external institutions, to put maintenance - whose status as an equal andoften-critical corporate element is by now uncontested - in an organizationalposition to perform its manifold technical and economic functions.

But one cannot help feeling, as one examines companies and maintenancedepartments and follows relevant literature, that maintenance is still in anunpleasant position; a position from which it can only extract itself with great effortA real breakthrough to the desired status has not been possible so far, or has beenonly partially successful. The uneasiness of the maintenance experts can beattributed to the fact that they were not able to keep pace with the general technicaland economic developments using the means and resources available to them.The routes taken to bridge the growing discrepancy were not always the best

Developments and Trends So Far

It was not all that long ago that production plants were generally wage-intensiveand equipped only with relatively simple machines. At that time, it was frequentlypossible to bridge machine operations in the event of a breakdown by increasingthe manpower. In an emergency, there were other machines and time, space,and/or capacity buffers to fall back on, without having to tolerate appreciablelosses. The demands placed on the maintenance team were relatively low.Things changed as machine-intensive factories separated production more andmore from manual labor. Larger, compacter, and more complex technical systemsreplaced simple machines. Investments rose along with the quantities producedand the possibilities to compensate and by-pass became more limited. Theproduction figures were decisively influenced by the operational reliability of theplants and breakdowns caused losses, which degreased the profits of thecompany.

At this stage of development the traditional maintenance organizations reached thelimits of their capability. It was the end of "management by foreman", based onintuition, personal initiative and improvisation, which had been common and hadfulfilled the requirements of the times.

Further mechanization and automation of production resulted in an almost totaldependency on machines. The tasks of operations personnel are limited to

operation and monitoring. High output levels, favorable profits, and low prices/unitcan only be achieved if the production plants function well. With increased in Tedinking of plants, there is also greater probability of a breakdown and greatertechnical and financial losses are expected as a result.


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5. CURRENT PRACTICAL SITUATION OF MAINTENANCEMANAGEMENT

The situation described here is based on studies carried out in companies as wellas discussions with maintenance experts in scientific and practical fields.

Misjudgment and Strategic Error of Corporate Management

The importance of maintenance within a company is generally underestimated. Onlyin exceptional cases is there Gear targets and long-tern strategies for maintenance.This permits considerable freedom of action and has created many weak points,which have been known for years but have not yet been eliminated.

Uncritical Ordering Att itude by the Client (Production)

Overvalued - too tight - repair deadlines lead to a high percentage of immediate

maintenance measures and consequently to great requirements for on-call services.Safety consciousness is exaggerated. In part, cost consciousness is verynon-discriminating; particularly as a sufficiently detailed overview of maintenancecosts and trends can often not be given.

Lack of or Inadequate Managerial Instruments in Maintenance

The important function of job planning is not given adequate importance. Thismeans that in many cases unplanned maintenance prevails instead of planned.Spare parts management is neglected. Records on the number and type of parts instock are rarely kept, making it impossible to control inventory.

Servicing and inspections are done only halfheartedly. Often there is a completelack of records on breakdowns or weak point analyses and repair. The work ordersystem is very inefficient and incomplete. Usually it is slow and nontransparent

Many of the weaknesses mentioned can be attributed to the fad that maintenance isnot adequately supported by data processing. There are - if any - many separatesystems as group-constrained solutions and no unique strategy for maintenancemanagement.

A survey of 25 industrial enterprises recently carried out by the Institute forEconomic and Management Sciences confirms these brief descriptions of thecurrent situation.


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6. INCREASING COMPLEXITY OF MAINTENANCE SERVICES

The ever-higher qualifications demanded of maintenance personnel become veryobvious when one remembers that some twenty years ago it was rather mechanicaland trade skills, which were required. Today, electronic specialists and softwareexperts play an increasingly important role.

In addition to extensive technical expertise, maintenance personnel are required tohave the ability to penetrate complex process sequences systematically. Thismeans that maintenance crews have to be able to think and act in aninterdisciplinary manner. This trend is clearly evident in the qualifications demandedof maintenance personnel servicing machine tools, shown in following total.

Qualifications Demanded of Maintenance Personnel

Servicing Machine Tools

Area of Specialization: Knowledge Required of:


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MechanicalMachine Tool Components and OperatingElements Geometry and Dimensions of theMachine ToolsSet-Up and Servicing of Machine ComponentsHydraulic and Pneumatic components

Electrical

Electrical Components and Control ElementsElectronic Components and Circuits

ElectricalMeasurement and

Control Units

Logic

Electrical, Electronic, and Fluid ControlElementsLogic Functions

Contact, Measurement and Control

Units

ControlEngineering

Basic Principles of ControlMeasuring Devices and TransducersTransformers

Principles of a Machine Tool Control SystemGeneral NC Control Systems

Programming

Principles of NC ProgrammingTroubleshooting and Recognition ofProgramming

Errors

TroubleshootingTheory of Fault-FindingLogic SystemsPractical Troubleshooting

Organization ofRepairs

Documentation of Planned and UnplannedRepairs


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Updating of FaultDocumentation


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7. MAINTENANCE STRATEGY


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7.1 Increasingly Stringent Safety Requirements

Increasing public sensitivity reinforces this criterion above all. Accidents in atomicreactors, chemical plants, and in airline travel have alarmed wide circles of thepopulation.

Maintenance experts know that maintenance, no matter how well executed andorganized cannot entirely preclude the sudden occurrence of damage.

However, there is no question that equipment weak points will be tracked downeven more efficiently in the future, through ultra sensitive servicing and inspectiondevices/systems.

7.2 Stricter Environmental Regulations

To satisfy legal requirements, many industries have found it necessary to installenvironmentally-friendly plants or plant components.

Reference need only be made to:

Coal-fired power stations - flue-gas desulphurizationSteel mills - filter plantsPaper and chem. Industry - waste water purification plants

The plant operators are thereby confronted with technologies, which are new tothem, and which also place special demands on the respective maintenancedepartment(s).

7.3 Maintenance-Oriented Design

Maintenance personnel have long called for a design process, which takes theneeds of, and for maintenance into consideration. Increasingly, their demand that"maintenance start with the design" is being put into action. One could fill entirelibraries with examples of unacceptable designs, which resulted in time-consumingand expensive repairs.

It has become widely accepted that the designer requires more than acomprehensive training. More and more, there is awareness that plant parts orcomponents may fail due to the negative impact of dirt, excessive cold or heat, peak

loads, operating errors, and/or the complexity of the plant as a whole or of thesystem on the plant part being designed.


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7.4 Relative Increase in Knowledge

Assuming the knowledge in the year 1800 to be 100 percent, its current level isapproximately 1600 percent and will presumably quadruple within the next twentyyears ff present trends continue. Innovations appear regularly and must be used ifan optimum is to be maintained.

7.5 Shrinkage of Time - Intervals

The volume of new knowledge within a given time frame is increasing at the samerate as progress is accelerating. The result is that patents, system designs, etc.within a specific field follow one another at shorter intervals.

7.6 Shorter Util ization Time of Systems, Processes and Programs

Systems, processes and programs consist of a multitude of single components,

which are modified or replaced by others as a function of the increase in knowledge.This frequently leads to a redesign of systems, processes, and programs, at ever-shorter intervals, thereby significantly reducing the effective lives of such systems.Up until now, it was estimated that a system, which was not updated regularly, hadan effective life of about ten years, but in the meantime one has to accept that it isconsiderably shorter.

Another consequence of this for system, process, and program development is thatthe conventional learning processes associated with development can now be atbest only partly oriented towards the actual situation. The learning processes mustrun concurrently to system develop it and must be directed towards a targetperformance from which one can rear to useful parts of the actual situation. Overall,the actual condition is generally so obsolete already that it no longer represents a

useful foundation on which to build.

7.7 Shorter Innovation Period

The time, which passes before a new invention can be put to practical, use (readyfor the market) is decreasing. If one traces the history of technology, one discoversthat the innovation period in earlier eras was quite long and that there wereinventions, which were not innovated at all, although they were actually practicalfrom a modem point of view.

Other inventions were developed twice, because at the time they were firstconceived, no one knew or devoted much thought to where and how they could be

profitably utilized.

When new systems are developed, it is advisable to consider not only the alreadyfamiliar possibilities, but also those, which are currently being developed oranticipated. If this is not done, then a system might already be obsolete by the timeit is implemented.


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7.8 Manifold Combinations Possible

Innovations of every type, be they technical, organizational, or other systems,consist of elements or groups of elements which have significance extendingbeyond the original purpose or field of knowledge. The choices and conceivablealterative increase exponentially as the level of knowledge and achievements rises.

The number of system components, which have to be taken into consideration fornew designs, reorganization, and/or adjustments, is constantly rising.

In practice, this means that there is not only a need for specialists who complementeach other and cooperate closely on developments, but that suitable systemtechniques must be applied in order to choose the most appropriate from the varietyof options available.


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8. What is Inspection (Condit ion Monitoring)?

Inspection or condition monitoring is a method of obtaining information regarding the

condition of machinery and is defined as "A series of activities to assure the most effective

use of the equipment during its life cycle".

A condition-monitoring program includes:

1. Planning

2. Performing

3. Obtaining measuring results

4. Analysis of results

5. Taking corrective action


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9. The Significance of the Application of Inspection Systems

Inspection should help the maintenance personnel examine machinery, (plant)

equipment. Condition monitoring is a concept, which involves the routine

organization of machine parameter values. These parameters are related to the

mechanical and operational condition of the machine.

To obtain such parameter values, technically high-developed measuring systems

are needed.

The information obtained by such inspection equipments can then be used as a

basis for necessary maintenance decisions. Such a maintenance decision could be

a planned shutdown at a suitable time, which in any case is more efficient than an

unforeseen breakdown.

As a result, many industries are now using predictive maintenance programs to

provide a guidance as to when maintenance should be performed, rather than

relying on fixed calendar dates (see the following example).


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10. Reasons for machinery failure

To build up a monitoring program it is essential to know the possible reasons of

machinery breakdown.

Possible reasons are:

- Natural wear

- Wrong operation (human error)

- Change of production (other products)

- Change of process parameters (temperature, pressure, flow etc.)

- Wrong design (manufacturers faults)

- External influence (damage from outside)


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11. TOTAL COST OF MAINTENANCE

The opinion that maintenance costs are comprised of personnel and material expenditures ha

in production shops became cost-conscious.

Maintenance Expenditures

(fix & variable)Costs of Breakdowns

Consequential costs

of Breakdowns

Personnel

Material, Spares

Energy

Tools

Rents

Education

Contractors

Product Volume

Delays

Lack of Quality

Process Energy

Sales Loss

Delayed Delivery

Delayed Income

Loss of Image

Loss of Customer


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Cost / Prod. Unit Cost / Min. ?

It's important to continuously control maintenance costs and to help keep the total cost ofpurpose, two significant values should be available in each production plant.

Maintenance Costs / Produced Unit

Cost of Loss of Production / Minute of Breakdown


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12. Maintenance Activities

Item Unit Description Operational Measures Pe

1 Motor Protection Switch Clean, check contacts and mechanical

function, check nominal current

adjustment

1 x ann

2 Miniature Breaker Clean, search for defects, check

mechanical function

1 x ann

3 Clean, search for defects, check

mechanical function

1 x ann

4 Discrepancy Control Switch Clean, search for defects, check

mechanical function

1 x ann

5 Miniature Control Switch Clean, search for defects, check

mechanical function

1 x ann

6 Pushbutton Clean, search for defects, check

mechanical function

1 x ann

7 Limit Switch Clean, search for defects

Check mechanical functionCheck contacts and function

Check oillevel and sealing

Lubricate bearings as required

2 6 x


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Check drive for abrasion

8 Spindle Limit Switch Clean, search for defects and abrasion

at drive, drive chain and contacts,

check tightness of locknuts, check oil

level and sealing

6 x mon

9 Centrifugal Switch Clean, search for defects, test contacts

and mechanical function

6 x mon


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10 Power Contactors Clean, search for defects, check

contacts, contact pressure and

mechanical function, lubricate bearing

as required

Size:

0 1

2 3

4 10

12 14

1 x ann

11 Auxiliary Contactors Clean, search for defects, check

mechanical function

1 x ann

12 Time Relay Clean, search for defects

Check adjusted values

Check mechanical function and move

ability of gear

Check electronic circuit

2 x ann

13 Timer Clean, search for defects, check

mechanical function

2 x ann

14 Fuse Isolator Clean, search for defects 2 x ann


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Lubricate contacts with contact grease

if required, Check engage of pawl

15 Thermal Release (Over Current Relay) Clean, search for defects, check

nominal current

2 x ann

16 Thermostat Clean, search for defects

Check electrical function

2 x ann


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17 Buchholz - Relay Test indication and release function\

Auxiliary means: Air pump

2 x ann

18 Measuring Instruments Clean, check for damages, Zero-point

and span adjustment

1 x ann

19 Optical-And Acoustic-Alarms Clean, search for defects

Check electrical function

1 x ann

20 Capacitors And Choke Coils Capacitor:

Clean and check for visual faults,

check discharging resistance

Auxiliary means: Ohm meter

Choke Coil:

Clean and visual check for faults

1 x ann

21 DC - Machines Clean Housing

Clean inside and insulation plates,

check length of brushes, change

brushes if minimal length has been

reached, check brushes for move

ability in the holders, check springs for

Weekly

2 x wee


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tension and mech.

faults, check connection wires for

tightness and for colour changes

through heat, check commutator for

visual defects

Bearings: Check oil-level at motor- Daily


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21 bearings, check function oflubrication-ring, check roller bearing

Check bearing temperature and noise

under load

Motor cooling fan: Clean air filter and

fan blades

DC-Motor:

Remove covers, clean the windings

and interiors, search for faults, check

functions

Speedometer: Search for any oil film, if

necessary clean and change packing

rings, check length of brushes andchange if required, check move ability

of brushes in the holders

Daily

1 x ann

1 x ann

Monthly


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22 Slip Ring Induction Motors Clean housing and air-inlet, searchfor faults

Check tightness and seals of protection

covers

Monthly

Weekly


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22 Slip Ring Induction Motors Clean Inside Housing

Search for possible faults in

connection cables, at brush holders,

Check length of brushes and contact

pressure of brushes

Change brushes if necessary


under load, Lubricate if necessary

Monthly

Monthly

Daily

23 Squirrel Cage Induction Motor Clean housing and air inlet, search for

possible faults

Check tightness and seals of protection

covers


under load, lubricate if necessary

Monthly

Weekly

Daily

24 Eldro-Brake Clean housing, search for possible Monthly


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defects, check oil level and seals

Add oil if requested

25 Accumulators Clean and check for possible defects

Check acid or alkalide weight

Weekly

Monthly


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25 Accumulators Clean, tighten and lubricate the

connections

Auxiliary means: Personal protection

equipment (gloves, safety glasses,

protection dress),

Acid meter

Alcalide meter

Distilled water

Vaseline grease

Monthly

26 Plate-Resistors Search for possible faults

Clean and search for faulty or

deformed plates. Check for loose

connections and for loose fix bolts also,

measure plate and insulation

resistance

Auxiliary means: Ohmmeter

Every tw

27 Potentiometer, Sliding Resistance Clean and search for faults

Check for abrasion at slider and

resistor

Every tw


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Check sliding pressure of slider

28 Control Magnet Clean and search for possible defects

Check move ability and clearance of

piston rod

Check seals and mechanical function

Every

month


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29 Brake Lifting Magnet Clean and search for possible defects

Measure protection-resistance

Auxiliary means: Ohmmeter

Monthly

30 Magnetic Device Clean and search for possible defects

Check oil-level and seals

Check for defects at the cabledrum,

Testing the function

Search for faults at slipring, brushes

and brushholders, check length of

brushes, replace if minimum length

Is reached, check contact pressure

Check cable and plug-sockets

connection for faults

Monthly

31 Load Lift-Magnet Check for faults, check connection and

sockets

Check abrasion of chain

Check if fixing bolts are tight and

covers are tidy

Visual check of cable

Monthly


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32 Power Transformer (Oil Cooled Type) Secure workplace as required

Clean transformer area

Clean transformer insulators, capacitor

batteries

Check discharge resistance of

capacitors

Every tw


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32 Power Transformer (Oil Cooled Type) Check Buchholz relays and protection

devices

Take oil sample fro high tension test

Auxiliary means: Ohmmeter, air pump,

clean sample glass, oil test device

Every tw

33 Control Board Clean and search for possible defects

or faults, check mechanical and

electrical function

Monthly

34 Push Button Panel Clean and search for possible defects

or faults, check mechanical and

electrical function

Monthly

35 Connection Box, Distribution Board Clean and search for possible defects

or faults, check seals and tightness of

housing

Check interior housing, connectors for

defects and tightness

Every tw

36 Starting Switch (Oil Type) Clean and search for possible defects

Check seals and tightness of housings

Monthly


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Check oil level

Check abrasion of sliding contacts

Check mechanical function


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37 Power Sockets Clean and check for any defects

Check interlocking

Every

month

38 Lighting Sockets Check for defects Every

month

39 Emergency Lighting Check for defects

Test function of batteries

Every tw

40 Lighting System Check for defects and faults

Check function

Every

month

41 Field Control Switch Clean and search for possible defects

Check drive contacts and sliders for

abrasion

Check length of brushes and change if

necessary

Every

month

42 Cabledrum (Springoperated) Search for defects, check functions

Check sliprings, brushes and brush

holders

Check cable and connection socket

Every tw

43 Crane Track Check fro defects at bus-bars, joints,

extension joints, insulators and

Monthly


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connectors

44 Crane Trolley Search for possible defects, check

tightness and seals of protection

covers

Distribution boards: Clean housing

Monthly


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44 Trolley and interior, search for any possible

defects

Limit Switches: Clean and search for

possible faults

Check mechanic and electric function

Supply cable: Check cable car, cable

holder and rail

Check for defects at bus bar, joints,

extension joints, insulators and

connectors

Current collector: Clean insulators,

search for defects, check brushes and

spring pressure

Check tension champ of cable fixing

Every tw


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45 Emergency Diesel Generator Check electrical function by test run Weekly


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Item Unit Description Operational

Measures

Period Qualification

46 Brush-Lifting-Device Clean and search for

defects or abrasion

Lubricate as required

Check mechanical

function

Every three

month

Electrical

Technician

47 Current Collector Check contact

pressure, lubricate joint

as required

Clean insulators, check

brushes for any defects

Check pulley for

defects or abrasion

Monthly Electrical

Technician

48 Welding Converter Clean housing and

interior, search for any

possible defects, check

length and contact

pressure of brushes,

check free movement

of carbon-brushes in

the brush holders,

Search fro possible

defects at commutator,

cables, plug and

sockets

Check mechanical

function

Every two

month

Electrical

Technician

49 Welding Transformer Clean housing and

interior, check cable,

plugs and sockets for

any possible defects

Control device: Search

for faults, check

mechanical function

Every two

month

Electrical

Technician


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me002 basic mechanics for non mechanical trades pr inst

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