FAQ's

Some of the questions we have been asked on a regular basis over the last 27 years as transformer oil specialists.

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  • Why do transformers have oil?

    Why do transformers have oil?

    The oil provides an electrical insulating and cooling medium.

  • Why does the oil need testing?

    Why does the oil need testing?

    Over time the insulating oil will oxidise and the presence of heat and moisture will cause irreparable damage to the insulating paper on the windings.

    Maintaining the oil cannot reverse the damage to the insulating paper but it can prolong its working life. Research by Stanley Myers, Joseph Kelly and Robert Parrish for their book A Guide To Transformer Maintenance (ISBN-13 978-0939320004) demonstrated that the working life of the insulation paper is halved by the doubling of moisture, but more surprisingly is that an increase of just 8 degrees centigrade also halves the working life.

    BS EN 60422:2013 (Mineral insulating oils in electrical equipment. Supervision and maintenance guidance) details the testing and maintenance of liquid insulated electrical equipment.

    Please note BS EN 60422:2013 replaced BS 5730 (Monitoring and maintenance guide for mineral insulating oils in electrical equipment)

  • My oil has high moisture content, what should I do?

    My oil has high moisture content, what should I do?

    In most cases Eden's regeneration plant will resolve the matter and ensuring you have correctly fitted desiccant breather will help maintain the transformer oil is a suitable condition. Also see "How did moisture come to be in my oil?".

    Please note desiccant breathers do need to be replaced from time to time, depending on the how the transformer used and sited.

    Moisture should be kept below 20 mg/Kg. Moisture, along with heat, leads to oxidation and "sludging" of the oil.

  • How did moisture come to be in my oil?

    How did moisture come to be in my oil?

    Moisture in the transformer oil is one of the leading causes of failures in a transformer, but it is also one of the most easily managed problems.

    The transformer oil could have absorbed the moisture from various sources, the most common being: transfer from the insulating paper or board, leaks in welds and poor seals on gaskets or a spent desiccant breather (see below).

  • My oil has been found to have a low electric strength, what should I do?

    My oil has been found to have a low electric strength, what should I do?

    In most cases Eden's regeneration will resolve the matter and ensuring you have correctly fitted desiccant breather will maintain the transformer oil is a suitable condition. Please note desiccant breathers do need to be replaced from time to time, depending on the how the transformer used and sited.

    Other tests, such as Dissolved Gas Analysis (BS EN 60567:2011) and Furans Analysis (BS EN 61198:1994) may also be recommended to ensure there are no internal problems with the transformer windings.

  • My oil has been found to have a high acidity, what should I do?

    My oil has been found to have a high acidity, what should I do?

    There can be a few root causes. Dissolved Gas Analysis (BS EN BS EN 60567:2011) is recommended to understand the root cause. The oil may need to be replaced and there may be an internal fault in the core of the transformer.

  • My oil has been found to contain polychlorinated biphenyl (PCB), what should I do?

    My oil has been found to contain polychlorinated biphenyl (PCB), what should I do?

    The remedial action will depend on a few factors. Please contact us for advice.

  • Would I not be better with continuous online filtration equipment?

    Would I not be better with continuous online filtration equipment?

    Continuous filtration will effectively remove moisture, dissolved gases and partials. On the face of it this is a good idea, but continuously removing gases thereby removes one of the most useful diagnostic tool for assessing the status of the transformer; Dissolved Gas Analysis (DGA). Without DGA you may well end up with unnecessary premature failure of the transformer of even potentially dangerous situations that could have been avoided.

    We believe the safest and most cost effective solution is to test the transformer at least to the standards and frequency laid down in BS EN 60422:2013 (Mineral insulating oils in electrical equipment. Supervision and maintenance guidance) and deal with any found issues as they arise. Safest is best.

  • Why does the oil need treatment?

    Why does the oil need regenerating?

    Dissolved gases, moisture and particles can be removed by the Eden equipment. A single pass through the Eden plant will remove particles, reduce dissolved gases from 10% to 0.25% and moisture to less than 10mg/Kg. We normally pass the oil three times though the plant. The results will be an electric strength of greater that 60KVA. This is achieved without loss of productivity to the customer because the transformer can remain energised during the process.

  • Why does the oil need replacing?

    Why does the oil need replacing?

    Regeneration cannot resolve acidity and polychlorinated biphenyl (PCB), the only viable solution is to responsibly dispose of the oil through and replace it with new.

  • Will my transformers need testing?

    Will my transformers need testing?

    Yes, all liquid filled transformers need testing on a periodic maintenance schedule, the frequency of the testing will vary on the age of the transformer, how each transformer is used and where it is located. Initially annual testing is recommended but this could be increased or decreased based on results and in line with the standards specified in BS EN 60422:2013 (Mineral insulating oils in electrical equipment. Supervision and maintenance guidance)

    Please note BS EN 60422:2013 replaced BS 5730 (Monitoring and maintenance guide for mineral insulating oils in electrical equipment)

    One off testing is useful and tracking over time provides a greater insight in to the transformers condition. Eden's database currently holds over ten years and 20,000 historical results.

    Maintenance Engineers should also check the requirements of their insurance policies with regards to testing to ensure compliance with customer obligations for cover.

  • What tests are available for my transformers?

    What tests are available for my transformers?

    Routine testing of:
    • Mineral oil to BS EN 60422:2013
    • Midel 7131 insulating fluid to BS EN61203:1995 IEC 61203:1992
    • Silicone Insulating Liquid to BS7713:1993 IEC60944:1988
    • Dielectric strength BS EN 60156:1996, IEC 60156:1995
    • Water content BS EN 60814:1998, IEC 60814:1997
    • Acidity BS 2000-1:1995
    • Visible contaminants
    • Dissolved Gas Analysis (DGA) BS EN 60567:2011
    • Furans Analysis BS EN 61198:1994, IEC 61198:1993.
    • Polychlorinated Biphenyl (PCB) Analysis to BS EN 61619:1997, IEC 61619:1997

  • Can I take the oil samples myself?

    Can I take the oil samples myself?

    Yes. We can supply all the equipment and or instructions you will need to take the samples yourself, our Online Store has our fill service testing product that includes the equipment, instructions, return postage and of course the test itself.

    If you already have sample bottles and simply need instructions please see our Helpful Documents page.

  • Can Eden visit my site and take the oil samples for me?

    Can Eden visit my site and take the oil samples for me?

    Yes Eden will travel to your site and take the oil samples to either test on site or from the laboratory depending on the urgency of the results.

  • What other inspections can Eden Transformer Oil do for me?

    What other inspections can Eden Transformer Oil do for me?

    Eden run a site wide inspection service of all your transformers. We will check oil levels & silica gel breathers then supply a full report of leaks, weeps and any replacements that are deemed necessary.

  • Whilst taking samples, can Eden Transformer Oil top up my site transformers and replace or fit new silica gel breathers?

    Whilst taking samples, can Eden Transformer Oil top up my site transformers and replace or fit new silica gel breathers?

    Yes Eden Transformer Oil can do all top ups and replace silica gel breathers where required when they take your oil samples or arrange a follow up visit to carry out any additional work.

  • How long will it take for the oil samples to be tested?

    How long will it take for the oil samples to be tested?

    Eden Transformer Oil will have your test results emailed to you within 2 hours of them coming off the production line.

  • How do I receive my test results?

    How do I receive my test results?

    Your results will be emailed directly to you as a PDF file so you can keep all your records electronically. If you would like paper copies this is also an option.

  • If my electrical equipment needs oil treatment or an oil change can Eden Transformer Oil do this for me?

    If my electrical equipment needs oil treatment or an oil change can Eden Transformer Oil do this for me?

    Yes. Eden Transformer Oil can bring to your site one of our Oil treatment plants and filter your transformer or switchgear oil back to the British Standards required. If your oil needs replacing; we will arrange an oil delivery to your site and replace the oil in the transformer or switchgear and then circulate the new oil using the oil treatment plant to ensure it is in the very best condition it can be.

  • Why is the new oil passed through the plant before being pumped in to the transformer?

    Why is the new oil passed through the plant before being pumped in to the transformer?

    Even new oil contains moisture from the atmosphere, the filter plant removes this in line to the transformer. Typically the moisture is improved to significantly below 10 mg/Kg and the resulting electric strength from 30kV to 60Kv.

  • Can Eden Transformer Oil dispose of my waste oil for me?

    Can Eden Transformer Oil dispose of my waste oil for me?

    Eden Transformer Oil is a registered waste oil carrier and will remove and dispose of your waste oil. We will supply the legal waste assignment certificates you require.

  • How much experience does Eden Transformer Oil have in the transformer oil industry?

    How much experience does Eden Transformer Oil have in the transformer oil industry?

    Eden Transformer Oil is a family run business started in 1985 by Alan Denbow and Edward Gregory after they witnessed too many transformers were having the oil replaced unnecessarily.

    Alan and Ed realised that regeneration would be more beneficial to the end customer through no loss of productivity, a higher specification oil and at a lower price, a complete win-win.

    In recent times the increasing cost of new oil and focus on the environmental aspects of incinerating potentially good oil and replacement with virgin product has made the business model even more important. Since 1985 Eden has operated in every industry sector : Steel manufacturing, Petro-Chemical, Paper Mills, Cement Mills, Water purification and pumping, Railway / Train repair, Military , Ministry of Defence, Airports, Food Processing, Glass manufacturing, Power generation and maintenance, and the latest wind farms.

  • Can Eden regenerate the oil / insulating liquid whilst the transformer is energised?

    Can Eden regenerate the oil / insulating liquid whilst the transformer is energised?

    Yes, this is one of Eden's key benefits to the customer. We recognise the importance of productivity in our customer's business and will filter live transformers to ensure no down time. Eden can also operate at weekends and through the night to ensure our customer's requirements are met and all services are operational.

  • Why regenerate rather than replace the insulating liquid / oil?

    Why regenerate rather than replace the insulating liquid / oil?

    Even new oil contains moisture that effects if performance. For example the moisture of new oil can be 40 mg/Kg giving an electric strength of 30kV. Filtered oil can exceed that to significantly below 10 mg/Kg and resulting in electric strength of 60Kv. Filtration is also cheaper for the customer and more so when the transformer is filtered live and thereby having no impact to the customer's productivity. Finally, and equally importantly, regeneration is better for the environment as no oil is incinerated and virgin products are not used.

  • Can Eden replace the oil if the acidity is too high or if the oil contains polychlorinated biphenyl (PCB)?

    Can Eden replace the oil if the acidity is too high or if the oil contains polychlorinated biphenyl (PCB)?

    Yes, when replacement oil is the correct choice, Eden will change the oil and the waste oil will be responsibly handled and destroyed in line with Environment Agency regulations.

  • Why do transformers have breathers?

    Why do transformers have breathers?

    As a transformer is 'loaded' the internal core will heat up causing the oil to expand, this expansion has to be accommodated and so a breather is in place to allow air to leave the transformer. The breather remove moisture form the air as it passes back in to the transformer during the contraction cycle of the oil. Eden can supply only or supply and fit the breathers, please see our online store or contact us for a quote.

  • Why does the breather need replacing?

    Why does the breather need replacing?

    The breather contains a desiccant to remove moisture from the air during the contraction cycle, over time the drying properties of desiccant is depleted. The frequency of the replacement will depend on various factors but the desiccant has an indicator to identify when the breather or desiccant needs replacing. Eden can supply only or supply and fit the breathers, please see our online store or contact us for a quote.

Mobile Purification Plant

Eden has been
treating transformer
oil on-site since 1985.

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site or off site service at
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