Maintenance and Testing of Electric equipment

  Maintenance and Testing of Electric equipment

 

General Introduction:

1.Objectives of testing significance of I.S.S. concept of tolerance, routine tests, type tests, special tests.

2.Methods of testing a) Direct,

                                    b) Indirect,

                                    c) Regenerative.

3.Classification and need of maintenance.

4.Advantages of preventive maintenance, procedure for developing preventive maintenance schedule, 5. Factors affecting preventive maintenance schedule.

6.Introduction to total productive maintenance.

Standard Formulation:

Standardization is the process of formulating and applying rules for an orderly approach to a specific activity for the benefit and with the cooperation of all concerned, and in particular for the promotion of optimum overall economy taking due account of functional conditions and safety requirements. It is based on the consolidated results of science, technique and experience.

Under the Bureau of Indian Standards Act, 1986, Bureau establishes Indian Standards in relation to any article or process and amends, revises or cancels the standards so established as may be necessary, by a process of consultation involving consumers, manufacturers, Government and regulatory bodies, technologists, scientists and testing laboratories through duly constituted committees of the Bureau.

For formulation of Indian Standards, BIS functions through the Technical Committee structure comprising of Division Councils, Sectional Committees, Subcommittees and Panels. Division Councils are set up by Standards Advisory Committee (SAC) in defined areas of industries and technologies for formulation of standards. These include representatives of various interests such as consumers, regulatory and other Government bodies, industry, scientists, technologists, testing organizations and consultants. BIS officer is the Member Secretary of the Division Council. The Division Councils setup Sectional Committees within their areas, define their scopes, appoint their Chairmen and members and coordinate their activities.

There are 14 Division Councils and over 650 Technical Committees that have so far developed over 19000 Indian Standards. Over 350 new and revised standards are being formulated each year by BIS. Indian Standards formulated by BIS cover various aspects such as product standards (specifications), methods of test, codes of practice, guides, recommendations, terminology, dimensions, symbols etc.

The committee structure of BIS seeks to bring together all those with substantial interest in particular project, so that standards are developed keeping in view national interests and after taking into account all significant view points through a process of consultation. Decisions in BIS technical committees are reached through consensus. As a policy, the standards formulation activity of BIS has been harmonized as far as possible with the relevant guidelines as laid down by the International Organization for Standardization (ISO). BIS, being a signatory to the 'Code of Good Practice for the preparation, adoption and application of standards (Article 4 of WTO-TBT Agreement, Annex 3)' has also accordingly aligned its standards formulation procedure.

 

There are two types of test mainly i.Type test; ii. Routine Test

 DIFFERENCES BETWEEN TYPE TESTS & ROUTINE TESTS

TYPE TEST:

These tests are intended to prove or check the design features. Type tests are done to check the characteristics on samples when new design or design changes are introduced. This test usually relates to the first unit manufactured by a firm to a given specification, after successfully passing which manufacture of the other unit may start.

ROUTINE TEST:

These tests are intended to check the quality of the individual unit under test. These test are done to ensure the reliability of test object and consistency of the material used in their manufacture. This test is essential to be performed on each unit before dispatching the product to site. It is presumed that every unit would also comply with the type test, since its design is identical.

SPECIAL TEST:

Special tests is done as per customer requirement to obtain information useful to the user during operation or maintenance. 

 

DIRECT METHOD OF TESTING

INDIRECT METHOD OF TESTING

BRAKE TEST

SWINBURNE’S TEST

FIELD TEST FOR SERIES MOTOR

RETARDATION OR RUNNING DOWN TEST

REGENERATIVE OR HOPKINSON’S OR BACK TO BACK METHOD OF TESTING

DIRECT METHOD OF TESTING

In this method, the DC machine is loaded directly by means of a brake applied to a water cooled pulley coupled to the shaft of the machine. The input and output are measured and efficiency is determined by

Ƞ= Output /Input

It is not practically possible to arrange loads for machines of large capacity.

INDIRECT METHOD OF TESTING :

In this method, the losses are determined without actual loading the machine. If the losses are known, then efficiency can be determined. Swinburne’s test and Hopkinson’s test are commonly used on shunt motors. But, as series motor cannot be started on No-load, these tests cannot be conducted on DC series motor. 

VIDEO Lecture :Maintenance & Testing of electrical equipment | Total Productive Maintenance TPM | Electrical tools

OBJECTIVE OF MAINTENANC:

The objectives of scientific maintenance are :

1. It increases the useful life of plant and machineries

2.It ensures the running of plant at maximum or near to maximum installed capacity and thus gives maximum possible return on investment.

3. It helps to keep the plant and machineries always ready for operation, thus increases operating time.

4. It ensures normal running of plant and machineries at minimum cost.

5. It gives proper protection of capital investment.

6.It ensures normal productivity and reliability of quality of output

7. It reduces number of accidents and ensures safe working conditions,

8. It helps to avoid crush situation that may arise in a factory out of breakdown of the plant or of machine.

 

ROLE  AND IMPORTANCE OF MAINTENANCE & REPAIR:

In modern age an industry is to face tough competition from other organization engaged in production of identical jobs or works. To fetch reasonable profit from such a competitive market, new methods and technologies are to be adopted on one hand and proper utilization of the existing facilities are to be ensured on the other hand. For proper utilization of plant and machinery systematic and scientific care and attentions are required. These systematic care and attentions are termed as maintenance.

For getting satisfactory and trouble free service from any electrical equipment or apparatus or any other electric machines, it requires careful planed programme of checking and inspecting and also for regular maintenance.

It is necessary to keep the proper record of inspection, insulation resistance and all maintenance and repair operation etc. Only then, it will be possible to find out the chronic troubles.

The periodic inspection and maintenance details may vary with the type of machine and its working conditions.

Moreover, with the development of science and technology we are gradually becoming dependent on atomization. These automatic machines require maintenance work of higher degree to keep them in working condition. So with the development of science and technology, the maintenance work need also to be developed to cope, with the changed situation.