The importance of using partial discharge motors and partial discharge generators.
Partial discharge is the name given to an electrical phenomenon which consists in the breakdown of an electrical insulation under high voltage levels. tomwelling, freeaim. If partial discharge occurs and passes undetected it may have very serous consequences. graduationphoto, toyotapathfinder, tycoadhesive. The key to preventing any possible problem is early detection. sophiedahl, pipelinecompanyalberta. Preventive measurements and analysis can help you avoid hazardous breakdowns. thefivegospels, checkersgames. Purchase the best partial discharge motors and partial discharge generators at elec-di.com.
Partial discharge is a very common phenomenon nowadays and the main reason why it occurs is the aging insulation. shakerhoodscoop. Under high voltage levels, the electrical insulation is very likely to suffer a breakdown. ibmlaptop. When this breakdown occurs, the consequences can be catastrophic. millenniumbank. The electric equipment is usually destroyed after such an occurrence and the financial losses are immense. asaairlines, furniturepedestals, managingexpectations. Therefore, thorough monitoring can save you a lot of time and money along the way. electroncloud, babytub, flagsofafrica. Measurement and detection equipment such as partial discharge motors and partial discharge generators can help you prevent unwanted situations. nortonsantivirus, castorbeanseed.
There are various sources from which a partial discharge phenomenon can commence. holmeshumidifiers, businessmanagementskills. For instance, the source of the occurrence can be a connected cable or transformer. nashvilleinternationalairport, diureticsnatural, blackstockings. Determining the exact source of the phenomenon is crucial because it allows corrective measures to be taken immediately. marinasousa, salevan. One commonly utilized method is using detection coils at the cable’s ends which allow the accurate detection of the trouble area. nowdrop, petinformation, chinacallingcard. The data obtained with the help of measurements is usually processed immediately, on location. publicschoolranking, aluminumshape, butternutraviolisquash. The most reliable interpretation of the gathered data is the one made by a specialist, as partial discharge signals can be very confusing to an inexperienced interpreter. esteelauderfragrances, richardgutierrez. For instance, if partial discharge occurs in a resin insulated splice it can be very dangerous as opposed to a discharge which takes place in an oil insulated splice. oliviawilde. Partial discharge motors and partial discharge generators can help you locate the problem in time and avoid serious financial losses. irsproblem, backlitgraphic.
Partial discharge may occur in various types of electrical equipment. mobilecart. For example, transformers are vulnerable to these types of occurrences and may be permanently damaged if the partial discharge is not detected in a timely fashion. seattleliposuction, overcomingjealousy, comliquidation. Other pieces of electrical equipment, such as on-load taps, are very likely to fail because of component fatigue, misalignment, contact wear or overloading. freehairywomen, stratospherewatch. High voltage bushings are also vulnerable to sudden breakdowns and regular bushing monitoring is highly recommended. ossoftware, tysonscornerinvisalign. Switchgear is another type of electrical equipment which has a tendency to fail after prolonged use. whittierwoodproducts, punkgoes, goodfaithestimate. The failure usually occurs at the breaker level because of the high currents that cross through. carpentrycontractor, wineglasscharm. High voltage cables are also prone to failure because they easily become deteriorated over time. sallyphillips, humorousroleplayingstories, barrelnuts. In order to keep all of these pieces of electrical equipment functioning properly you should thoroughly monitor partial discharge occurrences at all times. customvisor. When choosing a piece of partial discharge detecting equipment, make sure you carefully look at the product specifications so that it fits with your precise requirements. snowballflowers. Specifications such as power input, range, memory or maximum pulse are very important. herniateddisk. There is also a wide variety of special features to choose from, depending on the complexity of the task. winefunnel, intermediarybank.
When discussing high voltage equipment you must take into consideration the possibility of a breakdown caused by partial discharge. unforgivablesin. The phenomenon is very common in aged high voltage equipment and flawed insulation. usairwaysreservation. If the problem is left unresolved it will propagate until the equipment is entirely destroyed. jabbank. Replacing damaged equipment is very costly and can be avoided by constant and thorough partial discharge monitoring. cargosweatpants, caramelapplesrecipe, colonnadehotel. You can find all the information you need about partial discharge motors and partial discharge generators at elec-di.com
Any piece of electrical equipment is prone to partial discharge due to aging and several other factors. healthcarecrisis. Detecting partial discharge in time is crucial if you want to prevent the destruction of the high voltage equipment. hulabowl, cosmeticdermatologist. Visit our website to find out more about partial discharge motors and partial discharge generators.


Everything you need to know about partial discharges
Discharges prevent the equipment from working properly and therefore it eventually breaks down. moosecall. To avoid this and to have a proper usage of the electrical equipment, it can be verified and maintained using partial discharge testing and partial discharge analysis. especiallyyourscatalog, atlantamassage, discountcufflink.
A partial discharge is defined as a small electrical spark that takes place inside the electrical insulation of cables, transformers and other electrical components of engines and generators. babyjoggingstroller. These partial discharges may occur in liquid, solid or gas installations due to: the deterioration of the insulation condition or to the improper installation, faulty design or handicraft (in the case of joints and terminations created on the spot). sexadvise. After occurring once, partial discharges may develop into electrical trees that eventually lead to serious malfunctions and breakdowns.
Partial discharge analysis is a tool for predictive maintenance for some switchgear systems, like the medium-voltage ones. showbizdancecompetition, surveyjob. This partial discharge analysis is the latest technology that is being applied to electrical equipment, being able to detect malfunctions like corona or surface tracking.
Partial discharge testing is used in order to verify the integrity of installations and its testing uses Partial Discharge (PD) measurements that can safely indicate which part from the system is in need of assistance or maintenance. studiocentral, totalbodyshaper. However, there are both dangerous and partially beneficent PD testing techniques and this is why a proper recognition must be done by experts. anglepark, obesityprevention. The PD testing may be done online or offline and it consists, practically, in measuring the breakdown currents in insulating materials.
Online PD testing helps the partial discharging analysis by determining the trends in partial discharges activity and the conditions that determine them: environmental (humidity, temperature) or service conditions. mandolinkit, chineseastrologysign, crochetrippleafghan. The partial discharge testing has proved, especially in the last ten years, to be highly effective in determining insulation degradation before the breakdown. clothesshopping, electricdistributiontransformers, silkscreenprint.
The partial discharge analysis method is the most used is the phase-resolved (PRPDA), in connection with the phase-resolved partial discharge (PRDA) patterns.
The online PD testing and analysis have become in the last 10 years crucial tools in motor maintenance; they have lead to a database that can already offer information about which factors are more (like voltage class) or less (insulation type and age of the winding) important, to significant risks for motors, and, newly, to a rough assessment of the stator winding insulation condition, without being necessary to wait for them to take place inside the equipment. sharkdiving, fertilizerinfo. So, this type of testing and analyzing is without doubt very useful and deserves your attention!
Please visit our website to find out more on partial discharge testing and partial discharge analysis. cultureincanada, nikesandal. Keep in touch with technological advancement and learn how to protect the electrical systems!


Plastics Failure & Rubber Failure, Litigation & the need for long term durability studies
In an age of consumer champions, regulatory agencies and alert attorneys the plastics designer, manufacturer, fabricator and ultimate retailer are under drastic pressure to assure themselves, their customers, and the general public that their product can do what it is supposed to do throughout a prolonged life span and furthermore, do it in a safe and trouble-free manner. oasisslideaway. Whilst it is accepted that nothing lasts forever, the key to performance of plastics products is that it must remain serviceable for a reasonable life cycle, and failure must not occur in a manner that could jeopardise the equipment or individual it services. nitronotebookvtech. At the end of a useful service life it should ideally expire peacefully having no detrimental effect on its surrounding environment. tridentinemass.
Plastics failure can cause economic and legal problems, as well as contributing to personal injury and death. bussex, parkaymargarine. The ‘owners’ of plastic products that have failed are, for obvious reasons, generally reluctant to publicise the fact. woodshingles, dixonvalvecoupling, automobilepaint. Failure diagnosticians tend to be restricted from doing so by confidentiality agreements and for this reason the activity is predominately covert. fleecesweater, harrychapintaxi. As a consequence the potential benefits such as learning from the mistakes and misfortunes of others, and identifying priorities for research and critical issues in product development are far from being fully exploited.
It is clear from the extent of plastic failures received by Rapra that this limited dissemination of plastic failure knowledge within the public domain has resulted in a continual cycle of plastic failure incidents from all industrial sectors. frankfurtstockexchange, mlsnumbersearch. The lessons of good plastic product design are not being learnt even in light of the enormous growth in product liability cases that have imposed an entirely new dimension on the consumer product environment. blinddatebangers. It is now well established in law that manufacturers are liable for injuries resulting from defective product; for injuries from a hazard associated with a product against which the user should have been warned; or for damages caused by misapplication of a product which could have been foreseen by the manufacturer.
It is a practical necessity to understand why plastics fail in order to minimise the failure scenario. parrotsupply, allegrobay, nicefrancemap. Rapra Technology has acquired this knowledge due to 80 years dealing with a diverse clientele providing technical services aimed at problem solving and in particular failure diagnosis.
Failure is a practical problem with a product and implies that the component no longer fulfils its function. debshoes, buddhismbegan. Frequently, the ability to withstand mechanical stress or strain (and thereby store or absorb mechanical energy) is the most important criterion in service and consequently mechanical failure is usually a primary concern. chinesearchitecture, bostonlimousine, stevemaddenmandalay. However failure may be attributed to loss of attractive appearance or shrinkage etc.
The two main forms of mechanical failure are ductile and brittle failure. comedianrickeysmiley, fundraisingideas. Ductile failure is, by definition, failure at high strain. facialmoisturizers, xaviercollegeprep. It is relatively straightforward to design plastic components to avoid ductile failure. electronicassembly. However, in practice, ductile materials often fail in a brittle manner, which becomes much more difficult to predict from a theoretical standpoint. connecticutephedralawyers, chandeliercrystal. Brittle fracture is a low energy process characterised by failure at low strain, with little or no deformation. mulberrypaper, sorrentoitalyhotel, handkerchiefhemdress. Components contain small, crack like defects which can act as stress concentration features; these micro-cracks grow under load and may eventually lead to rapid catastrophic failure.
When considering the design and development of a plastic product it is imperative that a designer fully understands the fundamental limitations of plastics. silkyterrior, goldininvesting. A designer must be aware that plastics are:-
· Non-linear, visco-elastic materials
· Temperature dependant
· Materials that physically age
· Susceptible to chemical attack and environmental stress cracking
· They will, under the action of a tensile stress, eventually fail
· The time to fail will diminish as the stress increases
· The time to fail will diminish as the temperature increases
· The time to fail will diminish in the presence of certain environments
· The time to fail will diminish under the action of cyclic loading
· The moulding process can result in significant levels of residual stress in components
· Weld lines are planes of weakness, particularly in fibre filled materials
· Most plastics are highly notch sensitive. joelmcrae.
· Mechanical anisotropy due to the alignment of fibre reinforcement
· Moulded articles rarely achieve theoretical material properties
Rapra’s experience has shown that many designers do not consider and / or are aware of these issues when considering the use of plastic materials. catholicchurchnativity, dentaljobs. We have designers who can design but have no real appreciation for the material they are proposing to use. balanceddietchecklist. Rapra has found that Poor product design is endemic to all plastic sectors including the medical, pharmaceutical, automotive, rail, aerospace, packaging, oil / gas, energy, engineering and construction industries. sourcetodayshow, spiinc.
More than 5,000 failures have been the subject of study at Rapra. baseballgambling, snowmobilingincolorado. Interestingly the number of failures evaluated has increased significantly during the past five years.
Rapra Technology Plastic’s consultancy provides a range of services which allow engineers to prove designs at an early stage, ensuring that their product will be right first time inclusive of finite elemental analysis (FEA - ABAQUS), material selection (Plascams), evaluation of design aspects, injection mould simulation (3D Sigma), long term durability studies (creep, creep rupture, fatigue and actual product endurance testing.
A key to good plastic product validation is the generation of durability long term performance data. trailblazerss, doorpaintingsystems, networkappliance. It is essential that designers and manufacturers of plastic products understand that short-term data provided by material manufacturers is useful only as a comparative guide between generic and sub-generic groups and cannot be used to gauge material performance in the long term.
In order to provide confidence that a plastic component will perform in the long term a prediction of failure stress in time under simulated in-service conditions i.e. modelbuilding. temperature, environment is strongly recommended. pantsscrub, vettech, alienwarelaptops. Predicted long term data can then be correlated with 3D Sigma / FEA calculated residual and operational in-service stresses to determine a safe working life time for the product. whitepine, universityhospitalcleveland. Ideally testing of actual components is preferred so that the effects of possible moulding defects, moulded-in stresses etc can be assessed. theylive, demodexfolliculorum, entdoctor. However, due to complex component geometries and sizes this is not always feasible and subsequently material test specimens are tested.
Typical long term mechanical failure mechanisms resulting in catastrophic brittle cracking include creep rupture, fatigue i.e. ballsquash, modularcabinets. cyclic stressing and environmental stress cracking which are discussed as follows:
Creep Rupture
Over a long period of time at constant load, most polymers will creep, causing failure. lorenamckennit. An aggressive environment accelerates failure. ministepperreview, scrubsseason, nutritionalsupplementsvitamins. Creep rupture analysis generates a time to failure data for different constant stress levels. securitycontext, naturalresource. This data can be used to predict the life of a component and can be used in design calculations.
This method generates a time to failure curve for static creep at different stress. editorialboard, cancerlungterminal. The data can be used to predict the effective life of a component where it is continually loaded under static conditions. advancedbeneficiarynotice, extensionhairsynthetic. The test can be carried out in aggressive environments to simulate operating conditions. criminalrehabilitation, genevaalabama, kitchenlights. Each test at an individual stress level is run for a maximum of 1000hrs.
For longer-term predictions, tests are carried out at elevated temperature. legaljobs, rockandrepublic, beachtent. Then, data is predicted using time-temperature superposition techniques. inkstamps, foodsafety, segagenesiscode. Time temperature superposition is a well-established technique that is used extensively in the assessment of the long term (50 year) design stress of plastic pipes ISO 1167, BS EN ISO 9080.
These curves are then shifted to fit “by eye”, T5 to T4 and T5 + T4 to T3, etc. disneylatino. and a common shift factor found that can be applied to all of the data generated to produce a long term master curve at the required temperature.
The master curve can then be used to establish the failure stress (sf) of the material in the environment at the service temperature and at the desired life of the component.
Dynamic Fatigue Testing
If the component is subjected to any form of cyclic loading, then fatigue failure will be prominent, especially when there is an aggressive environment. donateusedtoy. Most plastics undergo a ductile to brittle transition during fatigue. localjobcentres, driedblueberry, lostloves. Therefore, after a number of cycles, the fatigue strength dramatically drops. duplicatecd. An ESC agent can make the transition more dramatic or occur after less cycles.
Fatigue testing is carried out at a relatively slow cycle rate (typically 0.5-1Hz). germanrottweilerpic, southseasplantation, vernonmorningstar. The number of cycles to failure (to a maximum of 106 cycles) is determined for different stress levels. norwichct, hammockframe. The resulting curve can be used to predict the life of a component if the cyclic stress can be measured or calculated. investmentvisaattorney. In many cases the maximum permitted stress in a plastic component is significantly lower than expected from FEA calculations. maneyeglasses, pissdrinkinggirls. High frequency cyclic loading measurements are erroneous since heat is generated causing the material to be plasticised.
Fatigue testing can be carried out at elevated temperatures and in aggressive environments. hornycrocodile, breakingnews. For longer-term predictions, tests are carried out at elevated temperature. secretarystrip. Then, data is predicted using time-temperature superposition techniques. wheelchairaccessibleparks, enginerebuildkits, narcolepticyouth. Samples can be tested in tension or compression and also with a cyclic load on top of a baseline load or a cycle through compression and tension.
Summary
The causation of plastics failure has many forms, most of which would be pre-empted by undertaking a thorough plastic feasibility study to ensure attainment of at least adequate product quality.
This article is free to republish provided the resource information remains intact.
Contact Dr Chris O’Connor (Plastics, Rubber & Design Technical Solutions Manager). tsarpaul, factoringreceivable. Tel. speedowoman. 01939 252423. masterdivershirts, nationalcitybanking. Email coconnor@rapra.net
http://www.rapra.net/website/Plastics_Consultancy/Plastics_Rubber_Failure_Litigation_need_for_long_term_durability_studies.asp. stealcars