Installation and Maintenance -Final-year

8/13/2019 Installation and Maintenance -Final-year

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University of Education Winneba

College of Technology, Kumasi

Faculty of Technical and Vocational Education

Department of Design Technology Education

Installation and Maintenance of Electrical and Electronics Equipment

Course code: EET 482

Level: 400 Semester: 8

Program: B. Tech. Education

(Electrical and Electronic Engineering)

Academic Year: 2012-2013

K. A. Dotche

Ph. D. Telecom. Eng. (Research candidate)

(Lecturer)


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Course objective

This course aims at impacting electrical and electronics equipment maintenance and

management. This includes general rules of equipment installation, their servicing and their

management within a chain/ plant production in order to optimize the general maintenance cost

involved and personnel safety.

Course outline

Maintenance and services definition and concepts, Different types of maintenance: corrective,

preventive, Intervention planning and advantages, Pareto Analysis in scheduling preventive

maintenance, Maintenance and Policies, Decision tree of maintenance strategy, Maintenance

oriented with software packages advantages over traditional maintenance.


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Contents

UNIT ONE: MAINTENANCE AND MANAGEMENT ----------------------------------------------- 4

1.0. Conceptual Fundamental -------------------------------------------------------------------------- 4

1.1. Definition and stipulation ------------------------------------------------------------------------- 5

1.2. Maintenance components ------------------------------------------------------------------------- 6

1.2.1. Structural analysis ---------------------------------------------------------------------------- 6

1.2.2. Maintenance flowchart ----------------------------------------------------------------------- 7

1.2.3. Sub-servicing contractor --------------------------------------------------------------------- 7

1.3. TYPES OF MAINTENANCE ------------------------------------------------------------------- 7

1.3.1. PREVENTIVE MAINTENANCE --------------------------------------------------------- 8

UNIT TWO: MAINTENANCE AND MANAGEMENT ---------------------------------------------- 10

2.1. Reliable Centered Maintenance -------------------------------------------------------------------- 10

2.2. Choice and strategy of maintenance policies ----------------------------------------------------- 10

2.3. Objective of RCM service ------------------------------------------------------------------------ 11

2.4. Decision tree ------------------------------------------------------------------------------------------ 12

2.4. Strategy and Policy in Maintenance --------------------------------------------------------------- 13

3.1. Data Information ------------------------------------------------------------------------------------- 14

3.2. Tools of analysis for the maintenance service --------------------------------------------------- 14

3.2.1. Evaluation of risk and failure of the equipment -------------------------------------------- 14

3.2.2. Analysis of fault effect and degree of failure ----------------------------------------------- 14

3.2.3. Pareto Analysis ---------------------------------------------------------------------------------- 15

UNIT FOUR: STANDARD FOR AN ELECTRICAL PREVENTIVE MAINTENANCE (EPM)

PROGRAM --------------------------------------------------------------------------------------------------- 16

4.1. Characteristics of maintenance service (Types) ------------------------------------------------- 16

4.1.1. Frequency of EPM ------------------------------------------------------------------------------ 16

4.1.2. Equipment Efficiency and aging -------------------------------------------------------------- 16


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4.2. Recommended Maintenance Practices ------------------------------------------------------------ 16

4.2.2. Air Circuit Breakers ---------------------------------------------------------------------------- 19

4.2.3. Arc Interrupters ------------------------------------------------------------------------------ 20

4.2.4. Operating Mechanism ----------------------------------------------------------------------- 20

4.2.5. Auxiliary Devices ------------------------------------------------------------------------------- 20

4.3. Vacuum Circuit Breakers ------------------------------------------------------------------------ 21

4.3.1. Air Disconnect Switches -------------------------------------------------------------------- 21

4.4. Oil Circuit Breakers ---------------------------------------------------------------------------------- 22

4.4.1. External ------------------------------------------------------------------------------------------- 22

4.4.2. Internal -------------------------------------------------------------------------------------------- 22

4.4.3. Auxiliary Devices ---------------------------------------------------------------------------- 23

4.5. Molded-Case Circuit Breakers ------------------------------------------------------------------ 23

4.6. Battery Stations / Chargers-------------------------------------------------------------------------- 23

4.6.1 Batteries ------------------------------------------------------------------------------------------- 24

4.6.2. Charger ---------------------------------------------------------------------------------------- 24

4.6.3. Safety --------------------------------------------------------------------------------------------- 24

4.7. Cables and Bus --------------------------------------------------------------------------------------- 24

4.7.1. Cables in Manholes ----------------------------------------------------------------------------- 24

4.7.2. Aerial Cables ------------------------------------------------------------------------------------- 25

4.7.3. Raceways ----------------------------------------------------------------------------------------- 25

4.7.4. Bus Duct ------------------------------------------------------------------------------------------ 25

UNIT FIVE: TRANSFORMERS -------------------------------------------------------------------------- 26

5.1. Dry Type Transformers ----------------------------------------------------------------------------- 26

5.2. Liquid-Filled Transformer -------------------------------------------------------------------------- 27

5.3. Protective Relays ---------------------------------------------------------------------------------- 28


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5.3.1. Visual and Mechanical Inspection -------------------------------------------------------- 28

5.3.2. Electrical Testing ---------------------------------------------------------------------------- 29

5.4. UPS Systems --------------------------------------------------------------------------------------- 30

UNIT SIX: Electric Motors --------------------------------------------------------------------------------- 31

UNIT SEVEN: CASE STUDY ---------------------------------------------------------------------------- 34

7.0. INSTALLATION AND MAINTENANCE OF TRANSFORMERS --------------------- 34

7.1. Introduction ---------------------------------------------------------------------------------------- 34

7.2. Accessories and fittings to a transformer ------------------------------------------------------ 35

7.3. Installation and maintenance -------------------------------------------------------------------- 35

7.4. INSULATION RESISTANCE TEST ---------------------------------------------------------- 36


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PART ONE: REGULATION AND PROCEDURES ON INSTALLATION

INSTALLATION OF PLANT

Definition

Plant installation is the process of putting a large piece of equipment (machine) in place and

connecting it to the requisite energy source such as electricity, gas or water so that it is ready for.

Stages of Installation of Equipment

Installation begins with taking delivery of the equipment and includes

1. Loading the equipment onto a truck2. Transporting it to site3. Unloading it from the truck4. Moving it to the place of installation5. Preparing the foundation and leveling6. Mounting the machine on the foundation7. Aligning components8. Test running

Procedure for preparing the foundation1. Study the machine and its specification and requirements2. Examine the place of installation3. Set out the foundation4. Excavate the floor where necessary5. Cast the foundation6. Position and secure in place the foundation bolts where possible

Procedure for mounting the machine on the foundation

1. Convey the machine near the foundation2. Lift and suspend the machine over the foundation3. Place wooden blocks on the foundation4. Lower the machine on the wooden blocks


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5. Check for alignment and ensure the hold-down bolts will fit into the holes on the baseplate of the machine correctly

6. Remove the wooden blocks gently one after the other7. Tighten the nuts in place as you check for leveling and alignment8. Connect the machine to the appropriate power source9. Test run and make the necessary adjustments10.commission

Plant Services

Servicing is the term used to describe the act of carrying out minor planned maintenance.

Planned maintenance refers to work organized and carried out with forethought , control and

records. It includes the whole range of maintenance and can equally apply to any type, that is

replacement, breakdown or preventive, provided that;

i. the maintenance policy has been considered carefullyii. the application of the policy is planned in advance, andiii. historical and statistical records are compiled and maintained to assess the results and

provide a guide for future policy.

The reason for servicing a plant is to ensure that:i. the machine must be available for start-up when neededii. the machine must not breakdown during production runsiii. the machine operates in an efficient manner at the required level of productioniv. the down-time for maintenance does not interfere with production schedules or runs.v. The downtime which may be caused by a breakdown should be at minimum.

Alignment

Shafts and other components are said to be in alignment when they are collinear at the coupling

point or when they are in-line with other machine components. Shafts are considered to be in

alignment when they are collinear at the coupling point. This implies that shafts which are not

collinear at the coupling point are misaligned.


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The term collinear refers to the conditions where the rotational centre lines of two mating shafts

are parallel and intersect. This is necessary so that the two shafts rotate just like a solid shaft.

Any deviation from the aligned or collinear condition, results in abnormal wear of machine train

components, such as bearings and shaft seals.

Several operational effects could send signals of misalignment, the most noticeable indications

of misalignment in rotating machinery, however, are shaft wobbling, excessive vibrations and

over heating of bearings.

Periodic alignment checks on all coupled machinery are considered to be one of the best tools in

a preventive maintenance programme. Such checks are important because the vibration effects of

misalignment can seriously damage a piece of equipment.

There are four alignment conditions. These are;

Perfect alignment Offset or parallel misalignment Angular or face misalignment Combination or skewed misalignment

Causes of misalignment

Misalignment may be caused by any one or a combination of the following;

Foundation movement or setting Thermal expansion Accidentally bumping the machine with another equipment Distortion caused by connecting piping Loose hold-down nuts, expanded grout and rusting shims.


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PART B: MAINTENANCE AND MANAGEMENT

UNIT ONE: MAINTENANCE AND MANAGEMENT

1.0. Conceptual FundamentalElectrical equipment failures account for millions of dollars in damage and lost business every

year. As electrical infrastructure continues to age, this problem is only going to worsen unless

active steps are taken to counter the trend. Ironically, more than two-thirds of electrical system

failures can be prevented by a routine preventive maintenance (PM) program. Studies show that

the failure rate of electrical equipment is three times higher for components that are not part of a

scheduled preventive maintenance program as compared with those that are. In addition, a

planned PM program allows the equipment owner to schedule the system outage at a time of

their choosing rather than having to correct major problems resulting from an always untimely

failure.

Therefore some production plant may define and organize the maintenance activities with regard to a

given standard or a recommended one by the manufacturer. The purpose of this standard is to provide the

insured with recommended practices and frequencies that would form the core of a regularly scheduled

electrical preventive maintenance program. All work associated with electric power systems and

equipment should be performed in accordance with accepted industry safety standards and work practices

Maintain To keeping something in its good state to insure the continuous of the plant

production

RepairTo fix something that has developed a fault, in such way that its efficiency is restored

Maintenance: - Work that is done to keep something in its good state or condition. (Dictionary

definition)

Ideally, maintenance is any activity undertaken with the aim of either retaining or restoring

something to a state or condition that enables its function very satisfactorily. The activities may


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not be confined to the technical aspect of the work only but may also include all supervisory,

managerial and administrative activities connected with the work.

In Engineering, however, activities may include replacements of parts, taking measurements,

conducting tests, adjusting parts of a machine and repairs. Maintenance can also mean all the

activities done to ensure that an item or material is retained in a serviceable state, including

testing, servicing inspection, classification in terms of serviceability, rebuilding, reclamation and

repairs.

1.1. Definition and stipulationThe Reference AFNOR X60-010, ought that, maintenance is the general actions which aim at

maintaining and fixing any equipment in a specific state to ensure a predefined service.

However, the German Institute of Normalization by its Reference DIN/RFA 311251proposes

that it is the general measures with goal to maintain and fix a given equipment/ good and to

appreciate its current efficiency in the production chain.

The Reference X60.000

It stipulates that maintenance is the general principles / rules or regulation in place in a given

organization /enterprise / production unit, to ensure the personnel safety and equipment

efficiency.

Meanwhile the Reference X60.010 identifies that maintenance might be the management of

equipment/ goods with a long term vision.

It may be argued that maintenance is a general management task which aims at ensuring the

working personnel safety and efficiency of goods/equipment in order to achieve a satisfactory

production. It may also be defined as all routine recurring work needed to ensure that an item is

kept in a good condition so that it can be used continuously for its intended purpose and at the

capacity, and efficiency at which it was designed.

In complex organization or firms software package are needed to manage maintenance

information eg. aerospace, military installations, large plants and ships. These software help


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improve supply chain communication as such material supply time is reduced, material

availability in increased, cost and repair times are reduced.

1.2. Maintenance componentsWe may identify three main parties, these are:

Structural analysis Functional flowchart Sub-servicing contractor

These components make use of a challenging factor, which is the time. We identify:

o Running before break time:o Total repair timeo Total break time

1.2.1. Structural analysisThis consists to define the necessary and sufficient activity/intervention out of a technical-

economic survey in order to identify the best method/strategy of maintenance which can

minimize the Global Maintenance Cost (GMC).

This accounts for the intervention cost, the failure/break cost, equipment-stored cost and the

damping stored cost.


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1.2.2. Maintenance flowchart

1.2.3. Sub-servicing contractorIt consists of assigning a partial servicing to a contractor. Thus, for some given equipment their

maintenance is undertaking by the contractor, who ensures and maintain the production

efficiency.

1.3. TYPES OF MAINTENANCE1. Scheduled maintenance (Preventive)2. Unscheduled maintenance (corrective)3. Conditional maintenance (predictive/ systematic) (depending on plant servicing)4. Curative maintenance5. Palliative maintenance

Maintenance Officer

Planning / Regulation

Unit

Work-Order Officer

Electrical Mecanical team

Storage-Officer

Maintenance Officer

Planning Unit

Work-Order Officer

Electrical / Mechanical team

Store and supply-Officer


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Maintenance

Preventive Curative Other

operations

Conditional

MaintenanceSystematicMaintenance

Palliative(repairing)

Curative(fixing)

InspectionControl

Visits

Testing

DetectionLocalization

Diagnostics

Innovation

Modification

replacement

(Standard)

Inventary

Diverse

1.3.1. PREVENTIVE MAINTENANCEThe term preventive maintenance refers to the care and servicing of an equipment or facility for

the purpose of maintaining it in satisfactory operating condition. It involves systematic

inspection, detection and correction of imminent failures before they occur or develop into major

defects.


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The maintenance engineer may test, measure, adjust or replace parts mainly to prevent faults

from occurring. It is to be noted that this type of maintenance occurs before failure to avoid far

more expensive damage. It is therefore designed to preserve and restore equipment reliability by,

for example, replacing worn out parts or components before they actually fail.

Activities of preventive maintenance (PM) may involve partial or complete or overhauls at

specific periods, change of oils, lubrication etc. An ideal PM program is necessary to prevent all

equipment failure before they occur. There is however, the element of human error and

equipment failure that can lead to failures despite carrying out PM. The importance of PM

cannot be over emphasized. However, it is often misunderstood by most people who think the

expenses involved are unnecessary.

In conclusion PM is conducted to ensure that an equipment is kept in a good working condition

and to extend its life span.

Corrective maintenance also called REPAIRS ensures that an equipment is working again. In

this instance failure has occurred and there is need for correction else the equipment cannot

function again. This may happen as a result of negligence of PM.


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UNIT TWO: MAINTENANCE AND MANAGEMENT

2.1. Reliable Centered Maintenance

RCM is an industrial improvement approach aimed at identifying and establishing the

operational, maintenance and capital improvement policies for the effective managing of the

risks of equipment failure.

It addresses the following seven basic questions:

1. What is the function of the item?2. What are the ways of failure in the provision of its functions?3. What events symptoms lead to each failure?4. What happens in the event of failure?5. Why does it matter?6. What systematic activities can be carried out to prevent it or satisfactorily minimize the

impact of its failure?

7. If a suitable preventive activity cannot be found, what other step must be taken?This type of maintenance lays emphasis on predictive maintenance (PdM) technique as well as

traditional preventive measures.

2.2. Choice and strategy of maintenance policies

This consists to define clearly:

What preventive maintenance is beneficial for our production/unit What are the economic resources requirements to minimize the failure/ cessation cost out

of the repair maintenance to curative maintenance.


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From unscheduled curative maintenance, wait for the problem/ cessation/ failure thenlook for what next to do and to solve the equipment/ failure/ cessation

Either to decide for predictive / systematic maintenance, this means to change all delicateequipment susceptible to cause the failure or cessation of the production plant/ unit, etc

2.3. Objective of RCM service

It targets to minimize the provisional global maintenance cost of equipment by identifying the

measures and tasks. This consists to evaluate either the preventive maintenance, or the corrective

maintenance for a given equipment in terms of its intrinsic and extrinsic elements is suitable:

Intrinsic elements: these correspond to the technical conception at designing process and

usually defined by the manufacturer such as: Lubrication, response to atmospheric effect, sub-

sets of the equipment which life spans are relatively shorter than the equipment one.

However, it may be pointed out that, these elements yield fatal cost such that any corrective

action cannot be undertaken for further improvement.

Extrinsic elements: these correspond to the usage of the equipment such as:

Production plant legislation constrains defining the periodic visits, inspections, controlsetc

utilization condition at the production planto the life span of the equipmento Annual utilization hourso The risks in terms of cessationo

The availability of the equipment

o The qualification of personnelo The real power used to the supply power

The personnel security and environment protection


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2.4. Decision tree

The decision tree is often used whereby we have little information about the running before

break time.

Fault

Ratio

Fault

impacts

security

Fault

impacts

security

Is the fault

Progressive

?

Is the fault

Progressive

?

Is the faultProgressive

?

Is the fault

Progressive

?

Conditional

(Unscheduled)

Maintenance

Preventive

Maintenance

Conditional

(Unscheduled)

Maintenance

Predictive

Maintenance

Conditional

Maintenance

Curative/

Corrective

Maintenance

Predictive

Maintenance

Curative/

Corrective

Maintenance

Yes

No

Yes

No

Yes

No

Yes

No

No

No

No

Constant

Yes

Variable

Yes


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2.4. Strategy and Policy in Maintenance

The choice of maintenance policy and strategy for equipment may rely on the deployment and

installation of the so-called no-destructive controllers e.g. alarm / signaling, indicating light

system. They are self-learning and auto diagnostic types of failure or any type of apparent fault.

These controllers are helpful in monitoring and management of the global maintenance cost.

The failure/ cessation

of the Equipment

May affect the

Production or

The personnel

security

The Cost

yields by

this failure /

cessation

Is it

Acceptable/

Manageable

Is it

Possible to use

Measurament/

Testing

Techniques

Is this

Method/

Technique

Good

for us?

Curative

Maintenance

Systematic

Maintenance

Predictive

Maintenance

Yes

Yes

No

No

YesNo

Yes


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UNIT THREE: DATA INFORMATION FOR MAINTENANCE UNIT (RCM)

3.1. Data Information

It helps the maintenance unit to appreciate any discontinuity or apparent fault in order and how

to schedule/ undertake the preventive maintenance with respect to the equipment in store. These

tools are also called the indicators or indicating parameters. They are defined in the Reference

AFNOR X60-020 and also emphasis on the maintenance unit response to a given fault. These

are:

Mean Time Between Failures (MTBF)It is a measure of the mean time between failures. It is the mean time of running time before

break/fault. It is a measure of the equipment availability after a failure has occurred. It is

measured in hours and defined by the manufacturer.

Mean Time To Repair (MTTR)It is a measure of the quality of response to a given fault by the maintenance unit/team.

3.2. Tools of analysis for the maintenance service

3.2.1. Evaluation of risk and failure of the equipment

This method aims at classifying the equipment with respect to the degree of risks or failures

likelihood during the production time. It is carried by out the survey of three to four technicians.

This survey allows scheduling the preventive maintenance.

3.2.2. Analysis of fault effect and degree of failure

It consists to point out a maximum likelihood record of failures of the equipment by a simple

rating exercise.

Failure =G*P


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Fault Value likelihood

Stop a sub-set of the equipment but not the production plant 1 exceptional

Stop the equipment but not the production plant 2 Rare/ scarce

Stop the production plant and fixing is needed 3 frequent

Stop the production plant and the personnel is unsecure 4 certain

With this rating exercise, the maintenance officer or maintenance unit may schedule a predictive

maintenance on relative equipment.

3.2.3. Pareto Analysis

It accounts for the preparation before interventions. It consists of adapting the preparation

activities in terms of demand and priority.

Pareto assumes that 20% of interventions correspond to 80% of the intervention expense yield

and 50% of interventions correspond to 95% of the cost of global maintenance interventions.

Consequently, the gain of intervention remains between:

20% to 40% of the cost due to maintenance intervention

30% to 50% of the fault and failures maintenance charges

The gain represents the observed and practical well planning intervention.

3.2.3.1. Preparation before intervention

It may consist of defining the procedures and rules to improve the maintenance Unit /team with

regard to the potentiality of a given site. In general, it is recommended that simple rules may be

applied as follows:

Write down, what we have to do Do exclusively what was written Record (short report) exactly, what have been done.


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UNIT FOUR: STANDARD FOR AN ELECTRICAL PREVENTIVE MAINTENANCE

(EPM) PROGRAM

Recommended Maintenance Practices for Electrical Distribution System Equipment

4.1. Characteristics of maintenance service (Types)

4.1.1. Frequency of EPM

In general, Hartford Steam Boiler recommends a frequency of once every three years for

conducting regular preventive maintenance on electrical equipment. Where applicable, this

standard will note components that require a more frequent EPM program to help ensure

reliability and operation.

It is recognized that individual locations may require more frequent maintenance due to the

physical environment or operational nature of the equipment. For example, harsh environments

where excessive moisture or dust may be present should have a more frequent EPM program.

Similarly, equipment that is used intermittently or equipment critical to a key process should be

considered for a more frequent program. Sound engineering judgment should be used in

determining if more frequent maintenance is appropriate.

4.1.2. Equipment Efficiency and aging

The equipment efficiency may be affected by age of utilization. Thus, as time goes on the

equipment may be unable to deliver its optimal efficiency. Therefore, in such a situation the

maintenance unit/ officer would have to schedule either a systematic maintenance or a predictive

maintenance running not necessary with respect to the manufacturer guidelines. It is assumed

that by then the maintenance/Unit have enough information on the equipment and how its failure

or cessation in the running process may affect the production.

4.2. Recommended Maintenance Practices

The following sections are segmented by equipment type. For each component, a recommended

minimum practice for preventive maintenance is provided; additional suggested practices are

presented for a more thorough EPM program.


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4.2.1. Switchgear

4.2.1.1 Enclosures

1. Ensure that all enclosure panels, doors, and structures are well-maintained in accordance with

the manufacturers specifications.

2. During deenergized maintenance, enclosures are to be vacuum cleaned of all loose dirt and

debris use of compressed air is not recommended since this may cause foreign particles to

become embedded in the insulation or damage insulators.

3. Any buildup of dirt or other contaminates that will not come off with vacuuming should be

cleaned with lint free rags using cleaning solvents recommended by the manufacturer.

4. All vents and fan grills are to be cleaned of all dust and/or dirt accumulations.

5. Ensure that ventilation openings are not obstructed.

6. Where seals and/or gaskets are installed, these should be examined and repaired or replaced as

necessary. All doors and access panels should be properly secured during operation.

7. Where heater elements are installed, these should be cleaned, examined for damage and/or

deterioration, and tested. Repair or replace heater elements as necessary.

8. In environments where there is an extreme exposure to adverse conditions, the frequency of

maintenance for enclosures should be increased as conditions warrant.

9. Electrical equipment rooms or vaults should be kept cleaned of dirt and/or dustaccumulations on a regular basis.

10. Doors and windows should be maintained in proper working order and kept closedduring routine operation.

11. Access doors should be clearly marked to alert personnel that live electrical equipment isin use.

12.Where ventilation and/or air conditioning is used, all fan motors should be cleaned andexamined for signs of wear and deterioration.

13. Fan blades should be cleaned of dirt and dust and bearings should be properly lubricated.14.Vent openings should be cleaned of all dust and dirt accumulations.15. Filters should be cleaned and/or changed as recommended by the manufacturer, or more

often if conditions warrant. Electrical equipment rooms should never be used as storage

areas.


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16.Electrical equipment rooms or vaults should be examined for evidence of water seepage.The tops of electrical equipment enclosures should be examined for evidence of water

since this is a common entryway that often goes undetected until a failure occurs.

17.The source of the water should be immediately identified and corrective measures takento permanently correct the condition.

4.2.1.2 Insulators, Supports, and Connectors

1. Inspect insulators and conductor supports for signs of cracking, broken pieces, and other

physical damage or deterioration.

2. Clean all loose dirt with lint free rags. For contaminates that will not remove easily, solvents

approved by the manufacturer may be used. Examine for evidence of moisture that may lead to

tracking or flashover while in operation.

3. Examine surrounding areas for signs of tracking, arcing, or overheating. Repair or replace

damaged insulators and supports as necessary.

4. Examine all bolts and connecting devices for signs of deterioration, corrosion, or overheating.

Ensure that bolts and connecting devices are tight, according to manufacturers specifications. Be

careful not to over torque bolts and connecting devices since insulators are easy to damage and

difficult to replace.

5. Where copper and aluminum conductors and/or connectors are used together, examine

connections for signs of galvanic action. Ensure that the connectors are properly used and

installed in accordance with manufacturers specifications. Apply an antioxidant compound to all

aluminum-to copper connections.

4.2.1.3 Conductors

1. Examine insulation for signs of deterioration, cracking, flaking, or overheating.

2. Examine all connections for signs of overheating, cracked or broken connectors, and signs of

tracking or arcing.


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3. Ensure that conductors are clean and dry.

4. Examine and clean all connections, and torque to manufacturers recommendations.

4.2.2. Air Circuit Breakers

4.2.2.1 Insulation

1. Remove and clean interphase barriers.2. Clean all insulating materials with vacuum and/or clean lint free rags. If it is necessary to

use cleaning solvents, use only solvents recommended by the manufacturer.

3. Inspect for signs of corona, tracking, arcing, or thermal or physical damage. Ensure thatinsulation is left clean and dry.

4.2.2.2 Contacts

1. Ensure that all contacts are clean, smooth, and in proper alignment.2. Ensure that spring pressures are maintained according to manufacturers specifications.3. On silver contacts, discoloration is not usually harmful unless caused by insulating

deposits. Clean silver contacts with alcohol or silver cleaner using non-abrasive cloths.

4. Manually close breaker to check for proper wipe, contact pressure, contact alignment,and to ensure that all contacts make at approximately the same time. If possible, a contact

resistance test should be performed to determine the quality of the contacts.

5. Older breakers equipped with carbon contactors generally require very little maintenance.Examine for proper pressure, deterioration, or excessive dressing which may interferewith their proper operation.

6. Draw-out contacts on the circuit breaker and the stationary contacts in the cubicle shouldbe cleaned and inspected for overheating, alignment, and broken or weak springs. Coat

contact surfaces with contact lubricant to ease mating (see manufacturers

recommendations)


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4.2.3. Arc Interrupters

1. Clean all ceramic materials of loose dirt and examine for signs of moisture, make sure theassemblies are clean and dry.

2. Examine for cracked or broken pieces. Dirt and arcing deposits may be removed by lightsandingdo not use emery cloth or wire brushes which may leave conductive residue

behind. Repair or replace as necessary.

3. Examine arc chutes for dirt and/or dust accumulations and clean as necessary. Dielectrictesting of arc shields may be recommended by the manufacturer. Check air puffer for

proper operation.

4.2.4. Operating Mechanism

1. Inspect for loose, broken, worn, or missing parts (consult manufacturers schematics forrequired parts). Examine for excessive wear of moving parts.

2. Observe that operating mechanisms function properly without binding, hanging, orwithout delayed action.

3. Ensure any lubrication is done according to the manufacturers specifications.4. Ensure mechanisms are clean, properly lubricated, and all bolts and screws are properly

secured. Repair or replace as necessary.

4.2.5. Auxiliary Devices

1. Inspect operating devices for proper operation and general condition.2. Ensure all indicating devices are fully functional and properly set.3. Protective relays and circuit breaker trip devices should be inspected and tested

according to manufacturers specifications and applicable industry standards such as

those issued by the Institute of Electrical and Electronics Engineers (IEEE) and the

National Fire Protection Association (NFPA).


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4.3. Vacuum Circuit Breakers

1. All maintenance is similar to that performed on air circuit breakers. As always, it isrecommended that the manufacturer be consulted for specific maintenance and testing

procedures.

2. The integrity of the vacuum chamber is often tested by applying a test voltage across theopen contacts of the breaker. However, this can be a destructive test and is therefore not

recommendedby Hartford Steam Boiler.

Caution: This procedure can produce X ray emissions, so personnel should maintain a safe

distance from the breaker if this test is performed. It is important to closely follow

manufacturers recommended procedures if conducting this test in order to ensure that proper

results are obtained. The breaker vapor shield can accumulate an electrostatic charge during

this test. Ensure that it is discharged immediately following the test.

4.3.1. Air Disconnect Switches

1. Inspect and clean insulators and conductors as with circuit breakers.2. Tighten connections in accordance with manufacturers specifications. Do not

overtighten as this may result in damage to connectors.

3. If cleaning solvents are used, ensure that they are as recommended by the manufacturer.Where abnormal environmental conditions exist, more frequent inspection and cleaning

may be required.

4. Check the operation of the arc blades, if applicable, and ensure proper wipe of the maincontacts.

5. Interphase linkages and operating rods should be inspected to make sure that the linkagehas not been bent or distorted and that all fastenings are secure.

6. The position of the toggle latch to the switch operating linkage should be observed on allclosed switches to verify the switch is mechanically locked in a closed position.

7. Operate switch manually several times to ensure proper operation, and then by motor ifpower-operated.


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4.4.3. Auxiliary Devices

1. Operating mechanisms should be maintained as with air circuit breakers.2. Where applicable, examine oil level indicators, sight glasses, oil lines, gaskets, and tank

lifters for proper conditions. Repair or replace as necessary and in accordance with

manufacturers recommendations.

3. Examine arc-quenching assemblies for carbon deposits or other contaminates. Followmanufacturers recommendations for cleaning.

4.5. Molded-Case Circuit Breakers

1. Molded-case circuit breakers should be kept clean for proper ventilation of the breakers.These types of breakers are usually tripped by a thermal element that senses an increase

in temperature due to excessive current draw. However, if dirt accumulates on the

surrounding of the breaker, the heat build-up may not be permitted to dissipate properly

and result in nuisance tripping.

2. Clean the breaker housing and inspect it for cracks or signs of overheating.3. Tighten all connections. Exercise the breaker several times to ensure the mechanism has

freedom of movement and to allow contact wiping.

4. In addition, larger duty circuit breakers (225 amps or above) should be electrically triptested to ensure proper operation of the trip elements and trip linkages. Refer to the latest

edition of the National Electrical Manufacturers Association (NEMA) Standard AB4,

Procedures for Verifying Field Inspections and Performance Verification of Molded-

Case Circuit Breakers. If possible, test contact resistance to ensure quality of breaker

contacts.

5. All molded-case circuit breaker panels should be cleaned of all dirt, dust, and debrisusing a vacuum.

4.6. Battery Stations / Chargers


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4.6.1 Batteries

1. Thoroughly clean all battery surfaces of dust and/or dirt accumulations. Clean andtighten all terminal connections. Remove any corrosion on battery terminals with

bicarbonate of soda.

2. Clean battery studs and cable ends. On stranded cable, if ends are corroded, cut off endsor separate strands and clean internally.

3. Check electrolyte levels and specific gravity. Variations of more than fifty (50) pointsbetween cells may indicate a bad cell.

4.6.2. Charger1. Clean all dust and/or dirt accumulations from charger.2. Clean all vent openings and ensure that they are free from obstructions.3. Check terminals and connections for tightness.4. Check all relays, lights, and other indicating devices for proper operation.5. If all cells consistently read low, check charger for proper operation.6. If electrolyte levels are low, check charger rate settings against the manufacturers

specifications. Consistently low levels may indicate the charge rate is too fast.

4.6.3. Safety

While charging, batteries emit explosive gases. Allow no open flames or sparks permitted near

charging batteries. Battery rooms should be well ventilated and smoking should not be permitted.

4.7. Cables and Bus

De-energize cables if they are to be touched or moved during maintenance.

4.7.1. Cables in Manholes


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1. Caution: Check for dangerous gases using a properly calibrated test meter beforeentering any confined space such as a manhole.

2. Inspect for sharp bends, physical damage, excessive tension, oil leaks, pits, cablemovement, soft spots, cracked jackets, damaged fireproofing, poor ground connections,

deteriorated and corroded or weakened cable supports.

3. Inspect for wear at entrance point and at supports.4. Inspect manhole for spalled concrete, proper ventilation and excessive moisture. Inspect

potheads for oil or compound leakage and for cracked / chipped porcelain.

5. Examine the manhole and cable grounding system to ensure its integrity.6. If cathodic protection has been installed in the manhole, it too should be evaluated.

Corrective action should be taken as appropriate to maintain the integrity of these

systems.

4.7.2. Aerial Cables

1. Check supports for excessive wear or deterioration, check cables for wear at supportpoints, inspect for mechanical damage from vibration.

2. At dead-ends, check cable for worn insulation, sharp bends, or cracks.4.7.3. Raceways

1. Check raceways for proper mechanical support of raceway and cables as well as checkinsulation for abrasion or cracks at support points.

2. Examine raceway joints for clean and tight connections.

4.7.4. Bus Duct

1. Bus duct joint covers should be removed to allow access for a thermographic survey ofthe energized bus under load.


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2. After de-energizing and grounding the bus duct, connections should be checked forproper tightness as well as evidence of overheating, corrosion, arcing, or other forms of

deterioration.

3. All loose or dirty connections should be cleaned and properly torquedbe careful not toovertorque the bolts.

4. Consult the manufacturer for recommended maintenance practices and torque values.5. The tops of the bus duct enclosure should be inspected for evidence of water or other

foreign matter that may contaminate the bus duct.

Testing

1. Suggested cable or bus tests include insulation resistance testing and polarization indextesting.

2. Recorded these tests to track trends that may indicate a deterioration of the cablesinsulation.

UNIT FIVE: TRANSFORMERS

1. Transformer data (such as, voltage, current, and temperature readings) should be recordedon a regular basis in order to determine operating conditions of the transformer.

2. Peak, or redline, indicators should be recorded and reset. Readings taken on a weeklybasis can provide important information about the loading of the transformer that is

needed before additional loads can be added to the transformer.

5.1. Dry Type Transformers


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1. Clean and inspect porcelain for signs of damage or deterioration. Repair or replace asnecessary.

2. Examine arrestor leads for damage and/or deterioration.3. Other suggested tests are 60 cycle spark over and hold tests, watts-loss and leakage

current tests, insulation resistance tests, and grounding electrode circuit resistance tests.

These should be conducted according to manufacturers recommendations.

5.3. Protective Relays

1. Inspection, maintenance and testing of protective relays should be done on an annualbasis in order to ensure proper and reliable operation.

2. All necessary precautions should be taken while working with protective devices toensure personnel safety and to avoid any unplanned interruption of service.

3. In particular, when working on control circuits, all current transformer (CT) secondariesshould be shorted to ground and never left open-circuited in order to avoid serious injury

to maintenance personnel.

5.3.1. Visual and Mechanical Inspection

1. Inspect relays for physical damage and deterioration.2. Inspect gaskets and covers for damage and/or excessive wear, and repair or replace as

necessary. Examine and clean the relay and enclosure of foreign materials, such as dust,

dirt, and moisture contamination.

3. Examine the condition of the spiral spring, disc clearances, contacts, and case shortingcontacts (if present).


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4. Check mechanism for freedom of movement, proper travel and alignment, and tightnessof mounting hardware and plugs.

5.3.2. Electrical Testing

1. Using an appropriate testing instrument, suitable for the relays being tested, conductelectrical testing of the relays in accordance with manufacturers recommendations and

IEEE testing standards.

2. For overcurrent relays, test the following functions of the relay at the established settingsspecified by the system engineer or manufacturer:

Pickup contacts should close when a current equal to the relay tap setting is applied to the

induction coil. Adjust the spring as needed to allow for proper operation.

Timing tests should be performed corresponding to two (2) or more points on the relays

timecurrent curves. One of the tests should be done at the specified time dial setting.

Instantaneous pickup test should be performed for the specified instantaneous setting, if

applicable.

Seal-in units should be tested to ensure that the contacts hold closed with the minimum

specified current applied.

Relay target should indicate when the relay has operated.


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If possible, the relays should be tested to ensure that operation of the relay will in fact cause a

tripping action of the respective circuit breaker. Relays that do not test satisfactorily or are found

to be defective should be replaced immediately to maintain the integrity of the protection

systems.

5.4. UPS Systems

1. This section provides general recommended maintenance guidelines for UninterruptiblePower Supply (UPS) systems. Since there is a wide variety of systems and equipment

available, the manufacturers instructions and recommendations should be consulted for

more complete and detailed maintenance requirements.

2. UPS systems are categorized in two basic ways: static and rotary. For the purposes of thisstandard, only static systems will be addressed.

3. When performing any maintenance and/or testing of UPS systems, follow allrecommended safety procedures as indicated by the manufacturer and required by OSHA.

Only fully trained and qualified persons with proper test equipment should perform UPS

maintenance.

4. Clean interior and exterior of cabinets and enclosures, ensuring that any areas ofcorrosion and/or deterioration are repaired as necessary.

5. Clean all vent and air circulation openings and ensure freedom from obstructions. Ifinstalled, clean cooling fan blades and motor housings.

6. Ensure that motor bearings are properly lubricated and that fan blades are properlysecured to drive shafts. Examine for signs of moisture contamination and correct if

necessary.

7. Clean and examine all electrical connections for signs of corrosion or deterioration, repairor replace as necessary.

8. Ensure all connections are tightened according to manufacturers specifications.9. As applicable, clean and test all breakers, disconnects, and relays as prescribed elsewhere

in these standards and as specified by the manufacturer.

10.Check all system alarms and indicating lights for proper operation.


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11.Check inverters for fluid leaks from wave-forming capacitors.12.Check capacitors for signs of bulging or discoloration.13.Examine transformers and heat sinks for signs of overheating. Maintain batteries as

prescribed in section 3.7 of this standard and as specified by the manufacturer.

UNIT SIX: Electric Motors

A maintenance program for electric motors should utilize proven and well understood testing and

inspecting methods performed by qualified knowledgeable personnel to identify and evaluate

conditions

6.1. Recommended Maintenance Practices and FrequenciesInstalled and runningActions typically performed with the motor installed and coupled to the

driven load.

Installed and offlineActions which require the motor to be electrically disconnected but can be

performed with the motor installed and coupled.

OverhaulActions typically completed during a routine overhaul. Additional testing / activities

may be required based on the individual situation.

Post OverhaulAfter completion of maintenance, the insured should review work report, ensure

all parts sent with the motor(i.e. terminal box, couplings) were returned and perform basic testing

of the motor before placing it in the stock system

. Maintenance

activity

Location Performance

characteristics

Frequency

Visual Inspection Installed and running Inspection should

look for:

Evidence of damage

caused by dirt, loose

parts, or foreign

objects.

Verification that air

6 months


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inlets are not blocked

Evidence of moisture

and/or dirt build-up

Unusual noises,

leaking oil seals, or

high vibration

Oil level gages (if

present) should be

checked

Evidence of

degradation of

foundation, bed

plates, anchor bolts

Evidence of oil rings

turning (if applicable)

Evidence of leaking

oil and water piping

and connections

Temperature

monitoring of

bearings and windings

Installed and running If motor is not

equipped with

installed sensors:

record bearing

temperatures and

stator temperature

using thermographic

imaging. This data

should be trended.

The monitoring

6 months


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should be completed

at similar motor

loading and ambient

temperature to allow

for accurate trending.

Vibration Installed and running Record and trend

vibration levels.

This should be done

by a trained and

experienced

technician, preferably

a qualified level II

technician.

6 months

Oil analysis Installed Sample and analyze.

Look at overall

conditions and check

for foreign matter,

additive depletion,

varnish precursors and

metallic elements.

Motor should be

shut down when

taking sample.

12 months

Running current Installed and running Record and trend all

three phase currents

and verify the currents

are balanced and do

not exceed nameplate

12 months


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rating.

Each phase should be

within +/- 5% of the

average of all three

phases

UNIT SEVEN: CASE STUDY

7.0. INSTALLATION AND MAINTENANCE OF TRANSFORMERS

7.1. IntroductionRegulations provide some guidelines as to how to install as well as maintain transformer. In this

section therefore you will be looking at some steps that need to be taken during the installation

and maintenance of the transformer. This section gives emphasis on:

the functions of some fittings attached to the transformer some important requirements for installing and maintaining transformers.


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four methods of cooling transformer.

7.2. Accessories and fittings to a transformerIn the construction of the transformer certain accessories are required for safe handling andoperation of the transformer. They include the following.

Lifting lugs -These are the places where the transformer can be held and lifted during handling

Drain valves- Drain plugs are provided at the bottom of the transformer and are used to drain

oil from the transformer.

Thermometers - These thermometers monitor the temperature of the transformer. In large

transformers the dial type thermometers are used. They are sometimes fitted with alarm contacts

which close at certain temperatures thus blowing an alarm.

Oil gauges- Oil gauges are fitted to enable variation of oil level with loading to be read. They

are usually the visual-light glass type.

Earthing terminals - These are terminals provided to enable earthing to be done on the

transformer. These may be on the framework which supports the tank or on the tank chassis.

Conservator- larger forms of transformers have conservators fitted to them. They are placed at

the highest point above the oil and must have enough capacity to contain variations in oil volume

as a result of temperature changes. The conservator allow the main tank of the transformer to be

completely fitted with oil thus preventing air from entering the tank and influencing the

properties of the oil.

Explosion vent- This is also called relief vent. Larger firms of transformers are usually provided

with this accessory which is bolted to the cover of the tank. It is a welded pipe with a diaphragm.

Under faulty condition gas pressure builds up in the tank which can cause explosion. However

the diaphragm bursts providing space for the gas and oil to escape to the atmosphere thus

rendering the tank safe.

7.3. Installation and maintenanceThe following are some points to consider during installation and maintenance of transformers

Because transformers heat as they operate they require enough ventilation should beprovided when installing them. Consequently transformers should not be installed too


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close to each other or very closed to a wall. Adequate space should always be provided

for air circulation.

Sometimes there is need to inspect the core and winding of the transformer and thisshould be done without having to disturb the foundation on which the transformer is

mounted. Therefore, adequate headroom should be provided to enable the core and

winding to be lifted out of the tank.

Foundation on which transformers are mounted should be of strong concrete. It shouldalso be free from vibrations which can lead to weakening

A dwarf wall should be built around the transformer. This is to contain escaping burningoil in the event of explosions.

If a transformer is mounted inside a buildings, there should be a trench which leads to asump outside. Such a trench should be filled with chips of stone.

Buildings housing oil-fitted transformers must be constructed with fireproof material.

The terminals of transformers must be checked regularly and ensured that they are firmand free from corrosion.

Samples of oil are taken for testing periodically. This is to ensure that the oil maintains itsproperties.

7.4. INSULATION RESISTANCE TESTThis is a test carried to ensure that, there is no possibility of leakage current occurring between

conductors and also between conductor and the general mass of earth. The test therefore, tries to

prove that the insulation used for electrical materials are of good quality. The instrument used


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for this purpose is the insulation resistance tester or megger. Some are batteryoperated and

others incorporate a small handoperated generator, which is operated by winding a crank. The

scale is in mega ohms but some also have a second scale in ohms, which can be used for

continuity testing.

Insulation resistance testers generate a voltage, which is twice the normal working voltage of the

circuit to be tested. This stresses the insulation as the test current flows through it and any faulty

condition can easily be detected. If the insulation is good less current will flow.

To conduct the test you must ensure that all loads as well as lamps are disconnected. Since thevoltage involved is high any control devices that contain semiconductor component must equally

be disconnected else they can be damaged. All switches however, must be closed.

For insulation resistance between conductors and earth all the phase conductors are connected

together and the test leads connected between the earth and the phase conductors (which are

connected together). The minimum acceptable reading is 1M.

The insulation resistance of other equipment and apparatus like iron; cookers etc can also be

tested. Here too the test is conducted between conductors and between conductors and earth.

You should note however that these equipment must first be disconnected completely from the

installation. The minimum acceptable reading should be 0.5M.

Documents

Installation and Maintenance -Final-year