Chapt. 1.1 Introduction.pdf

INTRODUCTION (EE603: Testing, Commissioning and Maintenance of Electrical Equipments)

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Contents  Course code, name, credits, CLO  Weightage for different components  Introduction to testing

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Introduction  Deterioration of electrical equipment is normal, and

this process begins as soon as the equipment is installed.  If it is unchecked, it leads to electrical failures and malfunctions.  Electrical Preventive Maintenance and Testing Program (EPM)  EPM program should consist of conducting routine inspection, tests, repairs and service.  EPM will minimize the hazards to life, reduces downtime (Stoppage/lost time). 4

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Why maintain and test?  A well organized EPM minimizes accidents, reduces

unplanned shutdowns, lengthens MTBF (“Mean time between failures”) .  Direct benefits of EPM are reduced cost of repairs, reduced down time, improved personnel & equipment safety.  Indirect benefits of EPM are improved morale of employees, better workmanship, increased productivity, discovery of deficiencies (shortages). 5

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Overview of EPM  Effective EPM can be summarized,

Keep it dry Keep it cool Keep it clean Keep it tight  There are basic four approaches to EPM. Run to failure Inspect and service as Necessary Scheduled Preventive Maintenance (SPM) Reliability-Centered Maintenance (RCM) 6

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 Run to Failure  Here EPM is not performed at all.  Degraded equipment is only repaired or replaced

when effect of degradation becomes unacceptable.  Mostly it leads to catastrophic failure*.  Small organizations which lack dedicated maintenance staffs often utilize this approach by default.  Large and more sophisticated organizations in the manufacturing sector apply it to noncritical equipment and systems. * A catastrophic failure is a sudden and total failure from which recovery is impossible. 7

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 Inspect and Service as Necessary  Advanced beyond “run to failure”

 Inspection on a more or less regular schedule.  Incipient (initial) failures are usually corrected

before they become catastrophic.  Many follow this approach and find it satisfactory.

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 Scheduled Preventive Maintenance (SPM)  EPM performed at fixed intervals of operating

calendar time, operating hours or operating cycles.  This is done based on manufacturer’s recommendations or industry standards.  It does not necessarily prioritize EPM according to safety or productivity significance, nor does it optimize the application of limited EPM resources.  Scheduled EPM is the predominant approach among relatively sophisticated operators of plants where productivity and safety is a serious concern. 9

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 Reliability Centered Maintenance  RCM involves specifying and scheduling EPM activities in

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accordance with statistical failure rate, life expectancy of the equipment, its criticality and productivity and continually updating EPM procedures and schedules. RCM is the most cost effective of the alternative approaches because it improves plant safety, reliability, availability while reducing maintenance cost by concentrating on items which are the most important. It reduces maintenance of less significant items. It also includes failure root cause investigation, correction, performance monitoring to predict failures. RCM is used extensively in military and is gaining acceptance among others too. 1/5/2018

Key factors in EPM optimization  Safety impact of equipment failure

 Productivity and profitability impact of equipment

failure  Cost of preventive maintenance (PM)  Failure rate and/or anticipated life of equipment  Predictability of failure  Probability of inducing equipment damage during maintenance and testing  Technical knowledge of plant maintenance staff  Availability of equipment information to support RCM 11

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Qualifications of EPM Personnel  The fundamentals of electrical power technology  General electrical maintenance techniques  Electrical safety methods and practices  Design and operation of equipment/system to be

maintained  Maintenance and testing procedures  For critical tasks, engineers’ experience should include preferably in an operating environment

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Systematic Failure Analysis Approach  Use a failure cause analysis to determine the proximate

cause of the failure.  Compare the proximate cause to past failures or conditions on the same equipment to determine if the problem has a systematic root cause.  If there is no systematic root cause, correct the failure, resume operation, continue performance monitoring.  If there is apparent root cause, initiate analysis.  If the problem is generic (general), contact other affected plants to determine if they have taken any corrective action. 13

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Cont…  If the problem is plant specific, determine if it is

attributable to a unique system design, or environmental factors or to operational factors such as maintenance, testing.  If the problem is related to system design, equipment application, or environment, determine specific deficiency.  If the problem is related to faulty operation, identify and correct the specific procedure.  Determine whether the root cause of the problem is a programmatic deficiency, e.g. in procedure writing, training, supervision etc., make appropriate corrections. 14

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Post Maintenance Testing  It provides best assurance that maintenance action were

accomplished correctly and equipment/system is functional.  It is heavily emphasized in the better performing plants.  Scope of the testing is broad.  All systems, subsystems, components are tested if engineering analysis emphasized them as significant for maintenance.

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Engineering Support  Maintenance engineering  System engineering  Design engineering  Training

 Spare parts and materials management  Quality Assurance  Quality Control

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Planning an EPM program  Maintenance Management Considerations  Technical Requirements  What should be included in the EPM program?

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Maintenance Management Considerations  Responsibilities

 Inspection  Scheduling  Work orders

 Record keeping

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Technical Requirements  Survey of plant equipments  Listing of plant equipments in order of critical

importance  A plan to perform EPM on regular frequency  Development of instruction and procedures for the EPM program

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What should be included in the EPM Program?  Electrical preventive maintenance and testing  Electrical repairs  Analysis of failures  Trending of maintenance and testing data

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Different Standards

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ICEA

Insulated Cable Engineering Association

NFPA

National Fire Protection Association

IEEE

Institute of Electrical and Electronics Engineers

ANSI

American National Standard Institute

NEMA

National Electrical Manufacturer’s Association

NEC

National Electric Code

IS

Indian Standards

BS

British Standards

IEC

International Electro technical Commission 1/5/2018

Overview of Testing and Test Methods  Manufacturer conducts electrical tests on equipment

before it leaves the factory  Factory Tests  Field tests are conducted to see whether newly installed equipment has been damaged, to indicate whether any corrective maintenance or replacement is necessary on existing equipments.  Electrical Testing divided into the following:  Types of tests  Types of testing methods 22

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Types of Tests Acceptance Test  These tests are known as start up tests.  Performed on new equipment, usually after installation and prior to energization.  It is required to check,  Equipment is in compliance with specifications  Benchmark for future tests  To check equipment installed without damage  To verify equipment meets in its design intent and limit 23

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Types of Tests Routine Maintenance Tests  Performed at regular intervals over the service life.  Concurrently with preventive maintenance and at 60% of final factory test voltage. 1. As found tests 2. As left tests

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Types of Tests  As-found tests  These tests are performed on equipment on receipt

(acceptance) or after it has been taken out of service for maintenance, but before maintenance work is done.  As-left tests  These tests are performed after maintenance, just

before energization.  Indicates degree of improvement and service as a benchmark for comparison for future tests. 25

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Types of Tests Special Maintenance Tests  These tests are performed on equipment that is known to be defective or has been subjected to adverse conditions that may affect its operating characteristics. Ex: Fault interruption by a circuit breaker:  This requires inspection, maintenance and test before it can be put back into service.

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Types of Tests Type test: It is conducted on first prototype of product to confirm the design specifications. This test is not repeated on other products of same type. e.g. temp rise test

Routine test: It is conducted on each product manufactured to confirm proper manufacturing of each and every units. This test is essential to be performed on each unit before dispatching the product to site. 1/5/2018