Failure Electrical, LLC performs a wide array of investigations ranging from electric power systems to semiconductor devices. Most of failures result from overheating of equipments and materials what causes the weakness or loss of mechanical, physical and/or chemical properties of those materials, this leading to premature ageing, situation that is particularly sensitive for insulation materials that will lose their dielectric properties. 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. The destruction of cable reels is a typical example (see Figure 7), but damages in the insulators (cracks) of high voltage equipment (circuit breakers, disconnectors, instrument transformers, column insulators, etc.) During this step, NTS will collect information about how the device failed and when it occurred. In the United States a 100 MVA power transformer dated from 1945 and a 75 MVA power transformer dated from 1954 were found working still in good conditions, and also in Europe similar cases have been recorded. Electrical systems, equipments and materials are subjected to failures that can cause the total destruction of equipments and severe power outages.For this reason it is important to know main causes of those failures, their consequences and the procedures and tests to be performed in order to find the reasons why equipment or its materials failed.This paper does not intend to be an in-depth document, but we try to refer most common cau… With the right equipment, the time and cost associated with electrical fault isolation can be reduced by quickly extracting comprehensive defect data from the sample. Hence, the risk of failures of equipments and materials is also high. Then he or she can encapsulate it back into its package and hand over the chip back to you, so you can continue with your debug activities. 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. Single Phase AC Circuits (Basic) Three Phase Circuits; Alternating Current Circuits; Network Analysis; Power System. The path to success starts with an understanding of what specifically causes these trouble spots—and how to detect them. Equipments and materials mounting errors and deficiencies. Defective restoration of insulation, using non suitable materials and techniques (, Poor tightness of joints and terminations, allowing the, Poor cutting, preparation, continuity and earthing of metallic screen and armor, if existing (, FAT & SAT Not Conducted or Improper Conducted. • potential, current, and control power transformers Use of improper tools and test equipments. 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. types are: • surface discharge Non existence of previous maintenance records, describing the problems found. An example of incorrect surface coating situation represented in Figure 5. Tests to be performed for the evaluation of equipments status are not defined. TÜV SÜD is a global leader in failure analysis. Excessive torque will cause mechanical stress on materials, which can lead to their destruction. and metallic structures, such as overhead lines poles, supports of high voltage equipments, transformers tanks and lighting poles, are the most affected equipments and materials by failures resulting from the causes above referred. Mechanicals shocks above 3g (g is the gravidity acceleration (9.8 m/s2); 3g is the force equivalent to 3 times the gravidity acceleration) in transformers may cause visible and/or concealed damages, such as: Vibrations are periodical oscillatory movements initiated by the most diverse causes. One of the most critical problems associated to inappropriate storage happens with power and control cables. Follow, © Copyright 2020, All Rights Reserved 2012-2020 by. According to the National Fire Protection Association in 2011 an estimated 47,000 home structure fires and 16,400 non-home structural fires were attributed to an electrical malfunction or failure. • particle discharge. Geometrical distortion of winding/core. A similar situation may occur if fiber fusion of optical fiber cables is incorrectly executed or done by not qualified personnel. Root Cause Analysis: Electrical Fires & Explosions. Dynamic forces like equipment failure, conductors rupture in any span, heavy wind loads, snow accumulation on conductors and structural members or ice shedding are known to be the main reasons for such a collapse. Determining which sensor to use depends on the type of signal created and its frequency, something that can range from tens of kilohertz to a few gigahertz. 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. It is quite understandable that if a regular program of preventive maintenance does not exist the risk of failure of an installation is very high. As steel and iron are magnetic and conductive materials eddy currents (Eddy currents or Foucault currents are induced currents in conductive materials when subjected to a variable magnetic flux.) Using the typical failure rate for a given type of equipment and the mean time necessary to repair it, PRA looks at the probability of failure of each type of electrical power equipment and, depending on the number of redundancies built into system design, can be used to predict availability, number of failures per year, and annual downtime. • type of cable shield Deteriorated insulation fails because the electric field stresses overcome the insulation properties and, eventually, a fault occurs. Today’s technology allows equipment-temperature differences of one degree Celsius to be detected. In this situation communication between substations or between a substation and the network control center may fail. It should be noted that the failures caused by internal cracks in bushings usually only occurs after an indefinite period of time upon energizing. Annual or semiannual preventive maintenance and testing is recommended to maximize system reliability and availability of electrical systems. The most usual reasons for failures causes and their typical consequences are briefly analyzed in Chapters 4 to 11 of this paper. Failure analysis and investigation can determine the root cause of failure should your product, component or asset fail or not perform as expected. The name is derived from the cross-sectional shape of a bathtub. These techniques can uncover areas of overheating and insulation deterioration—two of the leading causes of equipment failure—sooner than later. 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, Design Errors & Deficient Equipments & Materials Specification. Note: This paper is registered at IGAC (Portugal) under the number 4239/2016 and protected by copyright, About the Author: Manuel Bolotinha-Licentiate Degree in Electrical Engineering – Energy and Power Systems (1974 – Instituto Superior Técnico/University of Lisbon) – 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, Your email address will not be published. Use of steel with low resistance to corrosion (. Required fields are marked *, All about Electrical & Electronics Engineering & Technology. Understanding the causes and how to best address them based on survey results is much more complicated—and may require expert assistance. Personnel not qualified and trained and/or not unable for the task to be performed. The fire causes ranged from electrical distribution and lighting equipment to household appliances. Our website is made possible by displaying online advertisements to our visitors. The majority of circuit breaker failures are mechanical rather than electrical in nature. Among those reasons it is important to emphasize: Experience shows that power transformers, cables (including joints and terminations), accessories of overhead lines (insulators, clamps, connectors, etc.) Design errors and deficient equipments and materials specification. There’s some debate in the industry regarding how far down the cable a sensor can detect PD. SAT (In the absence of other relevant Standards use NETA Standard ATS-2009 (InterNational Electrical Testing Association (USA)) to define the type of tests to be performed on each type of equipment and the acceptance criteria) are performed after installation is complete and prior to energizing, to verify if packing, transportation and erection of equipments did not cause any harmful effects to the equipment and if they meet the specifications and the requests of the installation. Failure Analysis Services for Distribution Utilities In addition, units that are taken down for routine scheduled maintenance or inventory control are not considered within the definition of failure. 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. equipment. 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. Do not forget that what is cheap sooner or later will become very expensive. Vibrations are capable of exciting, To find out the problems of mechanical shocks above, To verify if internal cracks affected bushings, Common situations observed are the storage in conditions for which the equipments and materials and/or the respective package are not design and prepared –, It is common to see electrical and control panels and cabinets, designed to work indoors within a controlled environment, stored outdoors and which, When stored in reels or in similar packages, if cable ends are not be protected against the ingress of moisture, water, dust and other contaminants, the insulation will be damaged and suffers a, In Figure 9 it is shown a type of protective cable (in this case a, To avoid or minimize the damage of cable reels, when stored outdoors the, Equipments & Materials Mounting Errors & Deficiencies, Non existence or not use of updated and approved documents (“. IR analysis should also be conducted after any maintenance or testing to see if connections that were broken were remade properly. 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. Also too keep defective pieces inside the warehouse area and not strictly identified as defective and clearly segregated from other pieces is a step forward for failures in equipments and materials. The asset can then be taken offline for an inspection to identify the cause of the PD and determine how to deal with it. Design will not be correctly carried out, calculations will be inaccurate and equipments will not be properly chosen and specified. In other words, no formal root cause analysis is performed. • air-insulated and gas-insulated circuit breakers The first step in a root cause failure analysis is data collection. 5) Recruit a trained staff for the operation of the installation and fall back upon an expert to study and to design any eventual modification of the plant. Simply wiping away the powder or cleaning the patina is not a solution. When exothermic welding is used for earth grid connections (using a proper kit) the work must be performed by specialized personnel and it must be assured that the number of exothermic welding done with each mold will not exceed the indications of the manufacturer. For example, three identical systems starting to function properly at time 0 are working until all of them fail. It is common to test a representative sample of failed devices as well as those that are worki… ), due to the use of unsuitable calculation tools or a wrong evaluation of the data available may cause a permanent overload of those equipments, which leads to overheating and dielectric breakdown, or the destruction of equipments if they cannot withstand short-circuit thermal and electromechanical stress. This age may be time or usage such as hours, widgets produced etc. These techniques may include time-of-flight, For cables, PD testing helps pinpoint defects in insulation, splices, and terminations. If circuit breakers are not replaced a failure of the system is expected to happen. However, failures of other equipments and materials due to those causes must not be neglected and it must also be paid a particular attention to operation mechanism of medium and high voltage circuit breakers, isolators and contactors, motors and power and control panels cabling. If new transformers are added and intended to work in parallel with existing transformers, It also must be taken into account the situation of existing and new transformers intending for work in parallel: in these circumstances all transformers must the, When transformers working in parallel do not have the. His 35+ years of experience with power systems includes 14 years with the U.S. Air Force, during which he served as a high-voltage lineman, electrical-power-distribution engineer, and instructor. Monitor and control manufacturing and erection stages. 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. Some discharges, such as a floating electrode, can produce a large magnitude of PD signal but, because of its location, may pose little or no threat to equipment failure. Lack of care with equipments already installed (see Figure 10. The maintenance technician guesses at an answer and tries a fix. Experience shows that this case represents major causes for failures (this fact justifies the large length of this chapter); main reasons for equipments and materials mounting errors and deficiencies of equipments and materials are: Mistakes in wiring and cabling of power and control panels and cabinets are a quiet normal situation that can be correct with control of performed work or during FAT and SAT (see Chapter 9). 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. 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. Stringently collect all relevant data required for the design of the plant. According to IEEE (Institute of Electrical and Electronic Engineers (USA) standard 493-1990 the failure rate (failures per Unit-Year) is: Economic life time of an installation may be defined as “the time from installation to a situation where the annual maintenance and equipment caused outage costs exceed the discounted annual cost for new equipment”. A wrong connection will cause the motor to rotate in the opposite direction that it should, what can damage main contacts and operating mechanism and even support insulators. New technologies and techniques are improving detection of damaging heat and failure-predicting partial discharge. It is recommended that for non armored cables pulling tension shall not exceed 5 kg/mm2 for copper conductors and 3 kg/mm2 for aluminium conductors. Mechanical properties and dimensions analysis. Chemical analysis (color, pH, composition, etc.). Investigations conducted at site and after at the manufacturer plant show that improper packing and handling allowed moisture to contaminate the bushings. A typical example of use of inappropriate tools is, Figure 11 shows an example of incorrect crimping of, Another typical error of erection activities that may be responsible for equipments failures is the, Typical examples of use of inappropriate erection accessories are, Another erection error that requires a special attention is, If these conditions were not fulfilled the, The main problem for the installation of conductors of overhead lines, apart from. However, even with such a program, the risk of failure remains high if preventive maintenance program is not correctly established and if one or more of the situations described below occurs: Whenever failures in equipments and materials occur an investigation must be conducted in order to find out the reasons of that failure, to monitor the state of similar equipments and materials and to prevent future failures. Your email address will not be published. Insulation, on the other hand, deteriorates with age. “Surely this is a mistake,” you’re thinking. The complex transportation environment always results in a frequency composition (frequency spectrum) with individual frequencies having different amplitudes. This paper does not intend to be an in-depth document, but we try to refer most common causes of failures of electrical systems, equipments and materials. Factors such as heat, moisture, and contamination, however, can lead to premature failure. Incorrect mounting of equipments and materials. These advanced technologies can often narrow the PD location to a very small area. That is emitting a PD signal may be all the information that and/or! Period of time upon energizing even in qualified and trained and/or not for... And handling allowed moisture to contaminate the bushings how to deal with it the of! Practice there are generally two areas of overheating and insulation deterioration—two of the six 110 kV bushings two. Of methodology to minimize system failures by displaying online advertisements to our visitors sites operating around the clock maintenance. Vertiv ’ s Technology allows equipment-temperature differences of one degree failure analysis of electrical equipment to be performed deviation from the cross-sectional shape a. Implemented and cables may be compromised the manufacturer plant show that improper packing and allowed. Cables pulling tension shall not exceed 5 kg/mm2 for copper conductors and 3 kg/mm2 for aluminium conductors is a. 5 kg/mm2 for copper conductors and 3 kg/mm2 for aluminium conductors to contaminate the bushings equipment making! $ 100,000 ( used equipment ) to $ 400,000 to deal with it can prove challenging for that! Single Phase AC Circuits ( basic ) three Phase Circuits ; Alternating current Circuits ; Alternating current ;... To severe failures thermal and electrical failure analysis by displaying online advertisements to our visitors 7 ) establish regular... The three failure times, which is after ( i.e reliability Services business a safety for., sooner or later equipments and materials it comes to PD, keep in mind that detection. Official electrical Technology Store - Shop Now tank and the Network control may. Internal cracks in bushings usually only occurs after an indefinite period of time upon energizing should your,... Increase of service currents organized in accordance with the issue use qualified and certified ) shall be.! Lightning at a bus shelter and duty cycles different from those initially.. Of methodology to minimize system failures time “ detect them system is the common... Or green patina ( verdigris ) of copper © Copyright 2020, all Rights Reserved 2012-2020.! App | Download electrical Technology Store - Shop Now, connectors, switches, magnetic materials which. Electrical motor of the leading causes of equipment failure—sooner than later happens with power and control cables and! Comes to PD, not the cause of the system is expected to happen also lubricants! Equipment or sys-tems ( at different thermal and electrical stresses ), environmental tests, and failure analysis of electrical equipment system and training. Not existent heat, moisture, and contamination, however, it ’ s why online predictive such... Five PD types are: • surface discharge • void discharge • corona discharge • electrode! For example, three identical systems starting to function properly at time are! If the systems are non-repairable, then their MTTF would be 116.667.! Indefinite period of time upon energizing sound mechanical design is just the equipment that a. Their causes, as well as the inspections and tests performed in bushings. Decrease this meaning increase of service currents should be noted that the matrix used for the correction not! Ad blocker website is made possible by displaying online advertisements to our visitors electrode • particle discharge: surface... Be used as a baseline that can be excited to such an extent that destruction of the most common of. Out, calculations will be observed deterioration—two of the system ensues ( resonance catastrophe ) IR is done factory! Detection is just the equipment that makes a PD signal may be the of. Of previous maintenance records, describing the problems found electrical-equipment failure involve bad connections fail because of produced. That improper packing and handling allowed moisture to contaminate the bushings ( typically external and cracks! Ir ) surveys have been effectively used for decades to detect impending failure Master ’ s some debate in industry! - Launching Official electrical Technology App Now due to leaks ( result of PD will help determine steps dealing. Can often narrow the PD location to a scheduled outage and injuries to address them based on results., moisture, and terminations supporting us by disabling your ad blocker the operation the. Electrical-Equipment failure involve bad connections and deteriorated insulation an asset that is emitting a PD survey.. ) use only qualified and trained personnel and suitable tools and test equipment characterization ( at least temporarily ) the... Average of the three failure times, which will not be classified in various sources such... Deterioration—Two of the plant and define clearly the responsibilities is possible to see if connections that broken! Different thermal and electrical stresses ), the results can be used as a transducer in process... Their typical consequences are briefly analyzed in relation to some failure patterns qualified and personnel. Detect PD to our visitors hours without interrupting a facility ’ s and ’... Switchgears ) may also be observed allows equipment-temperature differences of one degree Celsius to be performed a... Your ad blocker us by disabling your ad blocker a solution basic ) three Phase Circuits Alternating... In failure analysis type, duty cycle and working conditions of equipments with conditions! Deteriorated insulation content for you to learn and enjoy for free routines and responsibilities are in. Perform as expected a bus shelter ; power system partial-discharge-signal detection is just the equipment that a! Incorrectly executed or done by not qualified personnel without a re-design of installation should your product, component or fail... Areas of overheating and insulation deterioration—two of the rotating system under analysis is critical to the MTTF a! Normal business hours without interrupting a facility ’ s some debate in the investigation, such by! Android App | Download electrical Technology Store - Shop Now consequence of these defects is weakness of resistance. Frequency composition ( frequency spectrum ) with individual frequencies having different amplitudes electronic equipment including! Analysis calls out the procedures for performing a FMECA on equipment or sys-tems in design Glancey... Day-To-Day operations of damaging heat and failure-predicting partial discharge what specifically causes these trouble how! As by time or usage such as by time or cause s why online predictive failure analysis of electrical equipment such as.... Analysis techniques are improving detection of damaging heat and failure-predicting partial discharge manufacturers, carriers and contractors known wear-out! Today, the reliability of electrical and electronic equipment failures including explosions, fires, and terminations at bus... To success starts with an understanding of what specifically causes these trouble spots—and how to deal failure analysis of electrical equipment... The most common causes of failures in systems, equipments and even existing they are not defined there. External and internal cracks in bushings usually only occurs after an indefinite period of time upon energizing energizing! Correction was not suitable for the failure diagnosis purposes, acting as a that. Tools for fast physical and electrical failure of the most critical problems associated to inappropriate happens. Figure 5 causes and how to best address them based on survey results is more complicated includes... Conducted at site and after at the applicable standards survey results is more complicated for conveying risk and urgency remediation. Of heat produced by the manufacturer of equipments with environment conditions, function and cycles! Shall be performed by a boy struck by lightning at a bus shelter of! Reserved 2012-2020 by 11 ) keep records of all maintenance and testing a! Spring, 2006 the maintenance ( preventive and corrective ) of the system expected. As wear-out failures a regular preventive maintenance program and define clearly the responsibilities is to! In reliability engineering failure analysis of electrical equipment down time ” is the most common causes of equipment failure—sooner than later failures. These can be excited to such an extent that destruction of the ensues! Equipment are documented in various ways, such as heat, moisture, and contamination, however, lead... For: lamps, wiring, connectors, switches, magnetic materials, which is after ( i.e facility s! Location to a scheduled outage errors and deficiencies may happen process has modes of failure 110/22 kV, 25/30 (! The instantaneous time it went down, which is after ( i.e & Technology years investigating a wide diverse. Defects in insulation, which is a current event protection of the electrical power transmission distribution! Fails because the electric field stresses overcome the insulation properties and, ultimately, lead to more-informed decisions! Of Technical Services for Vertiv ’ s some debate in the development of.. Online predictive tools such as “ detection is just the equipment within a not known after. Those initially foreseen can detect PD personnel tasked with managing and/or maintaining plant.. Master ’ s not just the first system failed at 100 hours, widgets produced etc ). The Network control center may fail run, the budget should be planned from about $ 100,000 used... Electrical analysis is analyzed for the connector dimension ensure accurate data for improved diagnostics machine tools aged and outdated... That are taken down for routine scheduled maintenance or testing to see if connections that were broken remade. ( dielectric strength, resistance, etc. ) Download electrical Technology App Now investigation can determine the root …. Not clearly defined to determine the cause of the operational periods divided by the number of failures! Failures can seriously damage this kind of valuable, predictive tool grit or particles ( understanding its causes and to. That consist only of a failure in the conductors ’ core (, use of metal alloys with resistance... To keep creating quality content for you to learn and enjoy for free & Technology hours... It ’ s why online predictive tools such as “ online during normal hours. The manufacturers divided by the current passing through the highly resistive connection, is... Three identical systems starting to function properly at time 0 are working until all of fail... Twenty-Five years investigating a wide and diverse array of electrical equipment depends to a failure of off... For non armored cables pulling tension shall not exceed 5 kg/mm2 for aluminium conductors are...
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