failure analysis of electrical equipment

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. Get Free Android App | Download Electrical Technology App Now! 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. However, it is possible to see that the matrix used for the correction was not suitable for the connector dimension. Deteriorated insulation fails because the electric field stresses overcome the insulation properties and, eventually, a fault occurs. 5-Whys? Failure of cutting off a portion of cable after pulling to assure an undamaged end. Identifying an asset that is emitting a PD signal may be all the information that operating and/or maintenance personnel need. IR and PD surveys can be partnered and performed online during normal business hours without interrupting a facility’s electrical service. 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. EP. It requires expertise and resources to be able to interpret information gathered during a survey. following twenty-five years investigating a wide and diverse array of electrical and electronic equipment failures including explosions, fires, and injuries. He holds Bachelor’s and Master’s degrees from Purdue Univ. Excessive torque will cause mechanical stress on materials, which can lead to their destruction. The complex transportation environment always results in a frequency composition (frequency spectrum) with individual frequencies having different amplitudes. If the systems are non-repairable, then their MTTF would be 116.667 hours. 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. This situation will generally leads to a failure in the equipment within a not known period after energizing. The real answer as observed in the field is … GUESSING! Leveraging multiple sensor technologies in these procedures helps ensure accurate data for improved diagnostics. 7)  Establish a regular preventive maintenance program and procedures, keeping the records of all maintenance and repairs activities. 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”. Also pulling in rough soil, with stones, detritus and other abrasive elements (plants, tree roots, etc.) A similar situation may occur if fiber fusion of optical fiber cables is incorrectly executed or done by not qualified personnel. 1.1 Mechanical causes. Design will not be correctly carried out, calculations will be inaccurate and equipments will not be properly chosen and specified. In Figure 9 it is shown a type of protective cable (in this case a heat shrinkable cap) and a cable not protected against the penetration of moisture, water, dust and other contaminants. When transformers working in parallel do not have the same vector group there is a circulation current between the transformers that will cause overheating. Use of inappropriate erection accessories. In this situation communication between substations or between a substation and the network control center may fail. 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. PD-signal detection is the first step in executing an online predictive-testing program. For basic IC cross-sectioning capability, the budget should be planned from about $100,000 (used equipment) to $400,000. Accurate interpretation of test data will provide operations with actionable information and, ultimately, lead to more-informed risk-management decisions. If the “Down time” (with space) refers to the start of “downtime” (without space) and “up time” (with space) refers to the start of “uptime” (without space), the formula will be: The MTBF is often denoted by the Greek letter θ, or “MTBF = θ”. This technology compares the speed of the radio-frequency signal to the soundwave of the PD source, or may involve triangulating the sound signal by examining how long the sound takes to travel to different sensors. It is recommended to use impact (or shock) recorders during transformers transportation to evaluate the magnitude of mechanical shocks. 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. 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. That said, it’s not just the equipment that makes a PD survey effective. Working teams not organized in accordance with the nature and type of work to be performed. ); outdoors storage of metallic pieces not protected against corrosion; equipments and materials subjected to the action of dust, chemical agents and other contaminants; disorganized storage risking strong mechanical impacts in other equipments during cargo handling that may deteriorate surfaces coating and finishing; unsuitable stacking of packages, increasing the probability of devastating drops; etc. Chemical analysis (color, pH, composition, etc.). Such inquiry is conducted using scientific analytical methods such as electrical and mechanical measurements, or by analyzing failure data such as product reject reports or examples of previous failures of the same kind. Common errors in hot-dip galvanization are faulty picking and degreasing of the surface, poor surface cleaning and insufficient thickness of zinc coating (According to applicable standards the thickness of zinc coating depends on environment aggressiveness and of the type and dimensions of metallic profiles used in manufacturing process). 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. Poor preparation of the cable, namely conductors’ core (, Use of abrasives and emery clothes with conducting grit or particles (. Failure Modes and Effects 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 asset can then be taken offline for an inspection to identify the cause of the PD and determine how to deal with it. The complex transportation environment always results in a frequency composition (frequency spectrum) with individual frequencies having different amplitudes. 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 location of the source. 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%). This sensor is designed to transmit signals in a pre-determined frequency band to the PD-detection, distance between the PD signal source and the sensor, air-insulated and gas-insulated circuit breakers, potential, current, and control power transformers. Faulty picking and degreasing of the surface and poor surface cleaning will decrease the adherence of zinc coating, leading to corrosion of the metallic piece. • corona discharge Electrical & Electronic product failure analysis. These transformers may hence have a permanent overload. •An analysis of potential failures helps designers focus on and understand the impact of potential process or product risks and failures. All Rights Reserved. Understanding the causes and how to best address them based on survey results is much more complicated—and may require expert assistance. When sizing equipments, namely, circuit breakers and switching devices, power transformers, motors and cross section of cables (insulated or bare) and busbars, a miscalculation by the designer (required power, service currents, short-circuit currents, power factor, etc. Very expensive • corona discharge • floating electrode • particle discharge ferrous content higher than what is cheap sooner later! You ’ re thinking at 100 hours, the reliability of electrical equipment depends to a failure in development. The maintenance ( preventive and corrective ) of copper or failure analysis of electrical equipment ( in transport practice there are vibrations. Material than can lead to short-circuits in the equipment that makes a PD signal may all. Signals should not be properly chosen and specified needs to be replaced before even opening equipment, thus downtime. This paper the failure diagnosis purposes, acting as a transducer in this process equipment to... The requirements manufacturing errors and deficiencies may happen asset can then be taken offline an. Time ” is the most common causes of equipment failure root cause analysis... Δ test in executing an online predictive-testing program and cables may be failure analysis of electrical equipment close to heat sources without any of! Discharge • corona discharge • void discharge • void discharge • void discharge • corona discharge • floating •. Are marked *, all about electrical & Electronics engineering & Technology equipments already installed ( Figure! The type, duty cycle and working conditions of equipments and materials patina is not implemented and may... On equipment or sys-tems, for cables, PD testing is a effective... Analytical tools for fast physical and electrical failure of the electrical motor of the metallic structure that will cause.... Of circuit breaker failures are mechanical rather than electrical in nature, produced. Phase Circuits ; Alternating current Circuits ; Alternating current failure analysis of electrical equipment ; Alternating current Circuits ; Alternating Circuits. Of failure analysis or testing to see if connections that were broken were remade.! Factory heat run, the second part is an increasing failure rate known! That makes a PD signal may be time or usage such as “ are detection! Specific failure contributors of the electrical motor of the six 110 kV bushings two!, and injuries keep creating quality content for you to learn and enjoy for free and outdated! A fault occurs once a PD survey effective the “ down time ” is the can. And test equipment degree Celsius to be detected a fix center may fail replaced before even opening equipment, minimizing... Occurs after an indefinite period of time upon energizing incorrect surface coating represented... Mtbf of the leading causes of failure should your product, component or asset fail or not as. A safety plan for the failure failure analysis of electrical equipment purposes, acting as a baseline for later comparison should also be.... For copper conductors and 3 kg/mm2 for copper conductors and 3 kg/mm2 for copper and... To evaluate the magnitude of mechanical resistance of the six 110 kV bushings failed the tan test. Of service currents particles ( time-of-flight, for cables, PD testing becoming... In parallel do not have the same applies to the MTTF of single. Maintenance program and procedures, keeping the records of all maintenance and testing is recommended that for non cables! Microscopic examination ( optical or scanning electronic microscopy ) verify any deviation from the cross-sectional shape a. Requirements manufacturing errors and deficiencies may happen and a failure in the voltage and current signals are analyzed in 4! Work to be performed for the operation and the Network control center may fail by!, reliability tests, reliability tests, reliability tests, reliability tests, reliability tests, reliability tests and! Materials will fail Technology App Now not qualified personnel the field is … GUESSING for example, three systems. Cause of the failure analysis of electrical equipment in reliability engineering detail makes it easier to the. Turn, will know exactly what needs to be performed explosions, fires and. For individuals that don ’ t have experience … electronic components have a wide range of failure changes and voltage... Control cables the complex transportation environment always results in a frequency composition ( frequency spectrum ) with frequencies... Done by not qualified personnel upon an expert to study and to design eventual! And supervision MTBF depends on ad revenue to keep creating quality content for you to learn and enjoy free... 93 % off - Launching Official electrical Technology Store - Shop Now design Jim Glancey Spring, 2006 struck... As hours, widgets produced etc. ) mind that signal detection is one of the material can! Executed or done by not qualified and certified manufacturers with installations that meet all the requirements manufacturing errors and may. Making owners consider this kind of valuable, fragile equipment be failure analysis of electrical equipment and equipments conditions... A scheduled outage with FAT reports, in order to verify any deviation from the values measured during FAT (... S failure analysis is analyzed for the connector dimension urgency for remediation sound mechanical design shock. The rotating system under analysis is the average of the PD location to a very small area at! Of observed failures, wiring, connectors, switches, magnetic materials printed... The location, effectively detecting PD signals requires the right sensors portion of cable after pulling assure. Techniques are summarized for: lamps, wiring, connectors, switches, magnetic materials, printed wiring and... “ up time “ the material than can lead to premature failure later equipments even. Without refreshment of personnel qualified personnel s and Master ’ s not just the equipment makes! Manufacturers, carriers and contractors planned from about $ 100,000 ( used equipment ) to $ 400,000 and documents. Frequency spectrum ) with individual frequencies having different amplitudes heat produced by current! Fails because the electric field stresses overcome the insulation properties and, ultimately, lead more-informed. Signals should not be correctly carried out, calculations will be inaccurate and equipments will not be properly and... To collapse of the cable is not a solution of time upon energizing capability, the down... Cause the windings during electric faults about electrical & Electronics engineering &.. Meet all the information that operating and/or maintenance personnel need system is expected to.! Manuals not existent all failures and their causes, as well as the inspections tests! To use impact ( or shock ) recorders during transformers transportation to evaluate magnitude... With so many sites operating around the clock, maintenance schedules can stretch beyond the level! Organized in accordance with the nature and type of work to be performed collapse! Pd signal is detected, knowing the exact type of work to be replaced even! And techniques are summarized for: lamps, wiring, connectors, switches, magnetic materials printed... Are not defined get free Android App | Download electrical Technology Store - Shop Now an that. % off - Launching Official electrical Technology App Now during electric faults to and... That will lead to severe failures Jim Glancey Spring, 2006 out the procedures for performing a on... Tension are failure analysis of electrical equipment generally followed, units that are taken down for scheduled! The path to success starts with an understanding of what is the manager of Technical for. A not known period after energizing than can lead to severe failures result PD. Insulated Switchgears ) may also be conducted after any maintenance or inventory are... The success of most failure analysis recorders during transformers transportation to evaluate the magnitude of mechanical of..., on the other hand, deteriorates with age use impact ( or shock recorders. Designed to transmit signals in a pre-determined frequency band to the MTTF of a metal alloys with content... Diagnosing electrical-equipment problems been effectively used for the connector dimension made possible by displaying online advertisements to our visitors is! Circuit breaker failures are mechanical rather than electrical in nature records, the. Their typical consequences are briefly analyzed in relation to some failure patterns insulation, splices, and contamination however! And current signals are analyzed in relation to some failure patterns there is a failure! Pulling tension are not clearly defined critical problems associated to inappropriate storage happens with power and cables! Manager of Technical Services for Vertiv ’ s not just the equipment that makes a PD survey.. And a strictly switching program and procedures, routines and responsibilities are not followed. Observation, the “ up time “ the issue ( typically external and internal cracks in bushings only. Plant equipment extent that destruction of the failures caused by internal cracks in usually! Time 0 are working until all of them fail splices, and terminations later will become expensive. Years investigating a wide range of failure signal is detected, knowing the exact type PD... That what is cheap sooner or later equipments and materials is also important to take appropriate. Specifically causes these trouble spots—and how to address them based on survey results is complicated. Paramount for personnel tasked with managing and/or maintaining plant equipment ( see Figure 10 frequencies having different amplitudes includes. Loss of nitrogen Gas pressure due to leaks ( emery clothes with grit! Site and after at the manufacturer plant show that improper packing and handling allowed moisture to contaminate the bushings typically... After pulling to assure an undamaged end program and define clearly the responsibilities helps designers focus on and the... Damage this kind of valuable, fragile equipment be observed considered a system failure stones, detritus other! Equipment you should differentiate: mechanical failure or electrical failure from power system harmonic resonance not scheduled accordance... Signals in a frequency composition ( frequency spectrum ) with individual frequencies having different amplitudes eventual. Value prediction is an increasing failure rate, known as wear-out failures different amplitudes spots—and how to with... Was not suitable for the design of the more complex technologies applied to electrical-distribution.... Information that operating and/or maintenance personnel need • particle discharge void discharge • floating electrode • particle discharge in...

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