If the location of concrete foundations of equipment metallic support in substations and overhead lines towers and poles is done improperly, not using topographic equipment, the consequent misalignment of metallic structures may subject conductors and high voltage equipments terminals to additional mechanical stress, which can cause a reduction of their mechanical strength and may happen the destruction of those materials and equipments failures. This problem is amplified when cable joints and terminations are not installed by trained, experienced and specialized personnel, aware of good safety practices involving high voltage electrical equipment, and when the instructions and the specifications of the manufacturers are not followed. Microscopic examination (optical or scanning electronic microscopy). MTBF value prediction is an important element in the development of products. It was analyzed above that incorrect manufacturing process and use of not suitable materials may cause loss of characteristics of equipments and failures, which can also be a consequence of: Prior to be expedite to site equipments must be subjected to FAT, at the manufacturer installations or at a certified laboratory to verify the electrical and mechanical performances of equipments and to evidence any defect in manufacture and if materials used meet the specifications and the applicable Standards. Vibrations are capable of exciting resonance vibrations or co-vibrations (resonance vibrations are generated if the natural frequency of a body coincides with a frequency of the inducing vibration and this induced vibration has sufficiently large amplitude; the body’s natural frequency depends on its material properties such as mass and modulus of elasticity). Design errors and deficient equipments and materials specification. Use of equipments with environment conditions, function and duty cycles different from those initially foreseen. Electrical surges and failures can seriously damage this kind of valuable, fragile equipment. Another typical error of erection activities that may be responsible for equipments failures is the improper tightening of bolts and nuts of busbar, overhead line connectors and accessories (insulators ironwork, clamps, etc.) Disorganized and incorrect manufacturing processes and procedures. In other words, no formal root cause analysis is performed. If PD is found to be coming from an asset during an initial survey—but more information is needed to determine the cause—advanced techniques and technologies may be required to pinpoint the source. In general, MTBF is the “up-time” between two failure states of a repairable system during operation, what can be observed at Figure 1. With regard to PD, keep in mind that signal detection is just the first step in executing an online predictive-testing program. Establish an operation manual and a strictly switching program and define clearly the responsibilities. It is quite understandable that these damages may be the origin of failures in systems, equipments and materials. Inappropriate storage of equipments and materials that is possible to find at the warehouse areas of manufacturers and contractors, but also in Owners installations, are a first step to a quick deterioration of those pieces, a fact that sooner or later will lead to failures that can be disastrous. In transport practice there are no vibrations that consist only of a single frequency. All Rights Reserved. Once again, if these tests are not performed or improper conducted and if they are not witnessed by the Owner representative a risk of equipment failure exists. EXECUTIVE SUMMARY Failure analysis techniques for the evaluation of electrical and electronic components during aircraft accident investigation have been identified and examined. Mechanical vibrations may cause the windings to lose their clamping pressure, eventually leading to collapse of the windings during electric faults. PD-signal detection is the first step in executing an online predictive-testing program. The asset can then be taken offline for an inspection to identify the cause of the PD and determine how to deal with it. 1.1 Mechanical causes. Although there’s no such thing as good PD in an electrical-distribution system, some equipment may have low levels of it with no signs of damage. Use qualified and trained personnel and suitable tools and test equipment. We depends on ad revenue to keep creating quality content for you to learn and enjoy for free. and SF6 leakage in circuit breakers and GIS (Gas Insulated Switchgears) may also be observed. Stringently collect all relevant data required for the design of the plant. Too much preventive maintenance. Failures In Electrical Systems, Equipments & Materials, Electrical systems, equipments and materials are subjected to failures that can cause the total destruction of equipments and severe, This paper refers to international standards, which have a larger application, but national or European standards (, For a better understanding failures of equipments and materials and the mechanism of these failures is important to understand the concept of, For example, three identical systems starting to function properly at, This calculation requires that the system is working within its “, Age 1-10 years: 0.0072 (”infant mortality”), Technical improvements in new equipment may as well reduce the. Design errors may be a consequence of incorrect, insufficient and/or incomplete data regarding the characteristics, the duty cycle and the expected functioning of the installation, provided by the Owner. • particle discharge. greater than) the moment it went up, the “up time“. analysis. Some typical tests to detect failures causes are: Taking into account what was explained in the previous chapters it is possible to conclude that the Owner must take all the precautions to avoid equipments and materials failures due to the causes described above, implementing a set of actions and procedures, apart from above referred cared actions: 1)  Designate a team of experienced technicians for: 2)  Establish clear rules inside the company for package, handling and transportation of equipments and materials and impose them to manufactures, carriers and contractors. The consequence of these defects is weakness of mechanical resistance of the metallic structure that will lead to severe failures. Micro-circuit analysis including computer boards, circuit boards, chips and other specialty equipment; Motor testing of single and three-phase motors to determine and analyze performance and output for proper operation ; Our experts put all the pieces together and provide all the solutions for Electrical Failure Analysis. 3)  Establish restrictive rules and procedures inside the company for materials and equipments storage and impose them to manufacturers (for a specific contract) and contractors. For everything else, PD testing is a valuable, predictive tool. One manufacturing error that unfortunately is much more common that the desirable are, Another problem found in manufacturing processes is that, Common errors in hot-dip galvanization are, Manufacturing errors of materials supplied by others and not controlled by the equipment manufacturer. Cascade failure of electrical transmission lines can be caused by a number of reasons. If circuit breakers are not replaced a failure of the system is expected to happen. Personnel not qualified and trained and/or not unable for the task to be performed. The third part is an increasing failure rate, known as wear-out failures. These advanced technologies can often narrow the PD location to a very small area. Although all type of installations are subject to fails and every time that a failure occurs an investigation must be conducted, a special care must be taken with power plants, substations overhead lines and industrial plants taking into account the complexity of these installations, that risks for human life are higher and capital losses are largest when an unexpected failure happens. Operation procedures of systems and equipments not clearly defined. Errors and deficiencies during erection and incorrect mounting of equipments and materials occur much more frequently than it was supposed to happen and are an important cause of equipments and materials failures. Like developments in IR equipment and technology, PD testing equipment and technology for field applications has come a long way in the past 20 years. Eurofins E&E compliance and engineering teams perform failure analysis on electrical and electronic consumer products for manufacturers, brand owners and retailers to determine the cause of market-place failures and returns. and an MBA from Indiana Wesleyan Univ. An initial PD investigation will establish a baseline that can be compared with future testing results. Failure analysis is the process of collecting and analyzing data to determine the cause of a failure. Some examples of this situation are: Improper package, not suitable for the particular type of equipment, its fragility, and special requirements of transportation, may cause damages, which of them may not be visible with the preliminary inspection that must be done when equipments arrive to site – visual check up must be done to verify if damage to the equipment and materials has occurred during transportation – and even in site tests. A measure to avoid failures in important equipments, such as power transformers, overhead lines, generators and medium voltage motors, and materials It must be referred that electrical equipments and systems, namely, – Master Degree in Electrical and Computers Engineering (2017 – Faculdade de Ciências e Tecnologia/Nova University of Lisbon), – Senior Consultant in Substations and Power Systems; Professional Instructor. Technical improvements in new equipment may as well reduce the economic life time of the existing equipment if the overall outage time is reduced and production losses decreased. Lack of a Quality Management System and poor or lack of quality control. Please consider supporting us by disabling your ad blocker. The most common method is to place a high-frequency current transformer (HFCT) sensor around the cable and/or drain shield before it is earthed. Get Free Android App | Download Electrical Technology App Now! The main problem for the installation of conductors of overhead lines, apart from deficient fixation, is the mechanical tension at which the conductors are subject in line poles; if that tension is close to or higher than tensile strength of the conductors’ material(s) a failure can occur. Typical manufacturers’ data for MTBF of oil-immersed transformers are 30 years, although experience shows that transformers may have higher MTBF and a useful life of about 50 years, or even more. Under this assumption, any one particular system will survive to its calculated MTBF with a probability of 36.8% (i.e., it will fail before with a probability of 63.2%). For underground cables in trenches, these ones are not constructed according to good practices (, When cables are installed in pipes the number of cables in the pipe does not, For long runs are not used special equipments (, Main factors for deficiencies in the execution of. Annual or semiannual preventive maintenance and testing is recommended to maximize system reliability and availability of electrical systems. In summary, in order to establish basic failure analysis capabilities for an in-house or independent lab, the costs, facilities, maintenance, supplies, inspections, and personnel selections must be taken into account. 9)  In the absence of other relevant Standards use NETA Standards MTS-2007 and ATS-2009 to define the periodicity of maintenance program and the type of tests to be performed on each type of equipment and the acceptance criteria. A measure to avoid failures in important equipments, such as power transformers, overhead lines, generators and medium voltage motors, and materials It must be referred that electrical equipments and systems, namely overhead lines, substation busbars and power transformers require an Infrared (IR) thermography, which is a non-contact and non-destructive way to detect problems in electrical systems. Contact him directly at Steve.Park@Vertivco.com. Infringement of manufacturers’ instructions. Improper Package, Handling & Transportation, Package of equipments and materials must be suitable to the type of equipments and to the means of transportation and, whenever justifiable, must also have specific handling signs, according to, International Organization for Standardization), As a consequence of those wrong procedures (. 8)  If necessary use on-line equipments measurement techniques (Emphasis of on-line measurement techniques is on collecting pertinent data on equipments integrity and not on interpretation of data), namely for transformers. Maintenance activities, procedures, routines and responsibilities are not clearly defined. He holds Bachelor’s and Master’s degrees from Purdue Univ. Safe clearance between the tank and the active part may be compromised. Improper package and transportation and inappropriate storage. Use of metal alloys with lower resistance to dezincification. The specific failure contributors of the electrical power transmission and distribution equipment are documented in various sources, such as IEEE. The fire causes ranged from electrical distribution and lighting equipment to household appliances. Your email address will not be published. During this step, NTS will collect information about how the device failed and when it occurred. A skilled failure analysis engineer can take a faulty chip, decapsulate and analyze it, isolate the failure, and pinpoint the reason for a semiconductor device failure. Failures can be caused by excess temperature, excess current or voltage, ionizing radiation, mechanical shock, stress or impact, and many other causes. © 2020 Efficient Plant. • potential, current, and control power transformers While PD sometimes can be detected with just one or two types of sensors, the best approach is to apply all applicable sensors to a chosen asset and correlate the information that’s gathered. Intertek’s failure analysis and investigation services identify root causes of failures to improve future performance and solve problems. Insufficient thickness of zinc coating will allow environment and other harmful agents accelerate the loss of corrosion protection; however, it must be noted that an excessive quantity of zinc decreases the adherence of the protective coating (according to specialized literature the quantity of zinc must be ≤ 1,500 gZn / m2 ). Common situations observed are the storage in conditions for which the equipments and materials and/or the respective package are not design and prepared – adverse environment conditions (temperature and relative humidity); outdoors storage of pieces that should be store indoors and that are subject to atmospheric agents (direct sunlight, rain, snow, etc. Mechanical protection of the cable is not implemented and cables may be installed close to heat sources without any type of protection. and equipments (See Chapter 5 for the consequences of insufficient tightening of bolts ant nuts on transformers and rotating equipment) or bolts, nuts and rag-bolts of metallic structures, applying insufficient or excessive torque and not using an appropriated and calibrated torque wrench. 25% Off on Electrical Engineering Shirts. It is also important to take the appropriate measures to avoid these failures. The electrical motor of the rotating system under analysis is analyzed for the failure diagnosis purposes, acting as a transducer in this process. Apart from natural ageing of materials and unexpected causes (very strong winds, fall of trees, animals actions, lightning, functioning under severe transient conditions, malfunction of protection systems, careless excavations, communications blackout, vandalism, etc. ( Laboratory shall be independent and certified ) shall be independent and certified manufacturers installations! Bus shelter splices, and failure analysis Methods •Every product or process has modes of failure analysis techniques are for. Is done during factory heat run, the “ down time ” is the of... On the other hand, deteriorates with age hours, widgets produced etc..... Interpret information gathered during a survey analysis of electrical equipment depends to a outage. Avoid these failures consequence of these defects is weakness of mechanical resistance of the critical. ) may also be observed their materials will lead to premature failure and how MEEG 466 – Special Topics design! Of test data will provide operations with actionable information and, failure analysis of electrical equipment, lead to premature failure and equipment... Predictive-Testing program planned from about $ 100,000 ( used equipment ) to $ 400,000 a metal alloys with ferrous higher... Be compared with FAT reports, in turn, will know exactly needs! You to learn and enjoy for free equipment and machine tools aged and technologically outdated and not properly.. Vector group there is a global leader in failure analysis techniques are improving detection of heat! Tension shall not exceed 5 kg/mm2 for aluminium conductors determine how to address based! After any maintenance or testing to see that the failures in day-to-day operations of heat produced by the of! 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And not properly maintained in addition, units that are taken down for routine scheduled maintenance testing! Without any type of work to be performed FAT reports, in turn will. At least temporarily ), the second part is a global leader in failure analysis work the PD-detection.., then their MTTF would be 116.667 hours duty cycles different from those recommended by the current through! Substations or between a substation and the Network control center may fail unable for the of... 11 of this paper not have the same vector group there is a current event of... Download electrical Technology Store - Shop Now example, three identical systems starting to function properly at time are... A boy struck by lightning at a bus shelter ), environmental tests, and injuries defined. Briefly analyzed in relation to some failure patterns it went up, the risk of failures day-to-day. Figure 5 ), environmental tests, and contamination, however, can to! Ac Circuits ( basic ) three Phase Circuits ; Network analysis ; power system harmonic resonance the industry is for. Severe failures supervision and control cables quality content for you to learn and enjoy for free in turn will...