Does HERING VPT provide transformer dry-out systems?

Yes. We offer small versions of our high vacuum EOK degasifiers which are designed to run unattended for periods of weeks at a time. They have a relatively low flow rate compared to the transformer oil volume. Our dry-out systems are optimized to not only reduce the transformer core moisture content, but also to degasify the transformer. This removes reactive oxygen from inside the transformer environment and slows down the aging process – something non-vacuum systems cannot do.

Fight transformer oil deterioration now with our transformer oil purification product line or the even more comprehensive HERING transformer oil regeneration systems. We will customize our systems to your specific requirements to get the most out of your transformers.

Are you rather interested in full scale transformer drying ovens for a more advanced treatment of your transformer? Then, our Hering transformer drying oven product line might be the right choice for you.

Still not found what you were looking for? Take a look at our products page for our most popular products or get in touch for customized solutions. We will build the right product for you!

Does HERING VPT perform service work on other manufacturers’ equipment?

Yes, in most cases we perform repair, service or upgrade work on other manufacturers’ oil processing equipment, transformer drying chambers and SF6 gas processing units. Please get in touch to discuss your specific servicing needs.

Fight transformer oil deterioration now with our transformer oil purification product line or the even more comprehensive HERING transformer oil regeneration systems. We will customize our systems to your specific requirements to get the most out of your transformers.

Are you rather interested in full scale transformer drying ovens for a more advanced treatment of your transformer? Then, our Hering transformer drying oven product line might be the right choice for you.

Still not found what you were looking for? Take a look at our products page for our most popular products or get in touch for customized solutions. We will build the right product for you!

Does HERING VPT provide onsite support?

Yes, we do. We can train your equipment operators and assist them at your site, or at one of your client’s sites, on both offline and online oil processing as well as any transformer drying task.

Fight transformer oil deterioration now with our transformer oil purification product line or the even more comprehensive HERING transformer oil regeneration systems. We will customize our systems to your specific requirements to get the most out of your transformers.

Are you rather interested in full scale transformer drying ovens for a more advanced treatment of your transformer? Then, our Hering transformer drying oven product line might be the right choice for you.

Still not found what you were looking for? Take a look at our products page for our most popular products or get in touch for customized solutions. We will build the right product for you!

Can your EOK and EOK-TORS systems be used on transformers that are energized and/or under load?

Yes. Our EOK transformer oil purification systems as well as our EOK-TORS transformer oil regeneration plants have the option to work on online transformers using our HERING TOLMS transformer oil level monitoring system. Our TOLMS unit also allows the conversion of most other manufacturers’ degasifiers to online systems – we, therefore, also supply the TOLMS as a standalone system. Please get in touch to find out more about this product.

Fight transformer oil deterioration now with our transformer oil purification product line or the even more comprehensive HERING transformer oil regeneration systems. We will customize our systems to your specific requirements to get the most out of your transformers.

Are you rather interested in full scale transformer drying ovens for a more advanced treatment of your transformer? Then, our Hering transformer drying oven product line might be the right choice for you.

Still not found what you were looking for? Take a look at our products page for our most popular products or get in touch for customized solutions. We will build the right product for you!

Why does HERING VPT quote different BDV values for the same system?

There are several different and acceptable testing methods in use globally, e.g. ASTM, IEC, each will produce a different value on the same oil sample – we provide you with all available BDV values, so that you can choose the value which fits your standards.

Fight transformer oil deterioration now with our transformer oil purification product line or the even more comprehensive HERING transformer oil regeneration systems. We will customize our systems to your specific requirements to get the most out of your transformers.

Are you rather interested in full scale transformer drying ovens for a more advanced treatment of your transformer? Then, our Hering transformer drying oven product line might be the right choice for you.

Still not found what you were looking for? Take a look at our products page for our most popular products or get in touch for customized solutions. We will build the right product for you!

Why is there sometimes a big difference in prices between different manufacturers’ oil purification plants for the same flow rate?

One of the main technical reasons is the choice of vacuum pump package used. For many purification plants and degasifiers, the vacuum pump package makes up as much as 25% – 30% of the price of the whole degassing system. Our HERING EOK Series of high vacuum oil purification plants can be configured with different vacuum packages to provide you with higher flexibility. The impact of choosing a less powerful vacuum pump package is typically reflected in the number of passes which are needed to achieve the desired oil parameters. In general, it is right to assume that the bigger the vacuum package, the lower the number of passes required to do the job – but also the higher the capital cost of the degasifier. Regardless of the configuration that you order, rest assured that our HERING systems are high quality systems and we do not compromise on the quality of the components that we use in our products.

Fight transformer oil deterioration now with our transformer oil purification product line or the even more comprehensive HERING transformer oil regeneration systems. We will customize our systems to your specific requirements to get the most out of your transformers.

Are you rather interested in full scale transformer drying ovens for a more advanced treatment of your transformer? Then, our Hering transformer drying oven product line might be the right choice for you.

Still not found what you were looking for? Take a look at our products page for our most popular products or get in touch for customized solutions. We will build the right product for you!

Can HERING systems remove Corrosive Sulfur from transformer oil?

Yes. The EOK-TORS series of transformer oil regeneration systems fully removes corrosive sulfur from your transformer oil. For a complete removal of corrosive sulfur and elemental sulfur it is essential that the regeneration process is continued to the endpoint as sulfur is one of the last contaminants to be removed during our process.

Fight transformer oil deterioration now with our transformer oil purification product line or the even more comprehensive, sulfur removing HERING EOK-TORS transformer oil regeneration systems. We will customize our systems to your specific requirements to get the most out of your transformers.

Are you rather interested in full scale transformer drying ovens for a more advanced treatment of your transformer? Then, our Hering transformer drying oven product line might be the right choice for you.

Still not found what you were looking for? Take a look at our products page for our most popular products or get in touch for customized solutions. We will build the right product for you!

Transformer oil deterioration: Why is transformer oil purification essential?

Oil in water as example of transformer oil deterioration

Transformer oil deterioration and degradation describe the adverse physical and chemical processes within the insulating liquid over its lifetime which negatively impact its performance and longevity.

Transformer oil deterioration must be minimized

The largest share of load bearing transformers operated around the world are filled with liquid – called the transformer oil. The transformer oil used in most transformers is a type of petroleum-based hydrocarbon which has been chosen due to its high dielectric strength and chemical stability.

Transformers in power distribution and transmission have to function reliably and as efficient as possible for many years to recoup the high upfront costs. For a long and efficient lifetime of the transformer, the quality of the transformer oil plays a key role.[1] The quality of the mineral oils and other dielectric fluids decreases during operation due to deterioration of the liquids.[2]

Transformer oil deterioration is caused by moisture and oxidation

Deterioration is mainly due to contamination, overheating, electrical stress, and oxidation. There are two main mechanisms occurring in the transformer oil during operation which cause deterioration.

The most common mechanism causing deterioration is moisture contamination. Moisture, and hence water, is present in the transformer oil as tiny droplets (emulsion) or free water at the bottom (demulsified water). Demulsified water contamination can be easily handled by extracting it through filtering or centrifugal treatment. The removal of emulsified water requires vacuum dehydration.[2]

Both the emulsified and demulsified form of water have profound effects on the insulating properties of the transformer oil as they reduce the dielectric strength of the liquid. Some of the dissolved water also gets absorbed over time by the paper insulation of the transformer which badly affects the insulation’s properties. This water content in the paper insulation is especially difficult to remove. Removing the moisture requires drying out with heat and vacuum.[2]

The second, less common deterioration occurs because of oxidation. This type of transformer oil deterioration is slower than that caused by moisture alone, but its effects can be more serious.

Oxidation results in acids in the transformer oil as well as increased formation of sludge. The oxidation speed highly depends on temperature. Transformers operated in high temperature climates, therefore, are especially susceptible to this type of oxidation.

To keep oxidation to a minimum, oxygen must be excluded from the transformer as much as possible. Oxygen can interact with the transformer’s inner workings as atmospheric oxygen and as oxygen occurring in moisture. Therefore, gaskets and seals must be maintained regularly and the water content needs to be kept as low as possible through vacuum dehydration using oil purifying plants.[2]

The ageing of the transformer and especially its paper insulation can be minimized by preventing the deterioration of the transformer oil and thus extending the transformer’s life expectancy significantly.[3]

References

[1] T. Rouse, “Mineral insulating oil in transformers,” Ieee electrical insulation magazine, vol. 14, iss. 3, p. 6–16, 1998.
[Bibtex]
@article{rouse1998mineral,
title={Mineral insulating oil in transformers},
author={Rouse, TO},
journal={IEEE Electrical Insulation Magazine},
volume={14},
number={3},
pages={6--16},
year={1998},
publisher={IEEE}
}
[2] P. Gill, Electrical power equipment maintenance and testing, CRC press, 2008.
[Bibtex]
@book{gill2008electrical,
title={Electrical power equipment maintenance and testing},
author={Gill, Paul},
year={2008},
publisher={CRC press}
}
[3] J. Sabau and R. Stokhuyzen, “The electrochemical stability of mineral insulating oils,” in Electrical insulating materials: international issues, ASTM International, 2000.
[Bibtex]
@incollection{sabau2000electrochemical,
title={The electrochemical stability of mineral insulating oils},
author={Sabau, John and Stokhuyzen, Rolf},
booktitle={Electrical Insulating Materials: International Issues},
year={2000},
publisher={ASTM International}
}

Fight transformer oil deterioration now with our transformer oil purification product line or the even more comprehensive HERING transformer oil regeneration systems. We will customize our systems to your specific requirements to get the most out of your transformers.

Are you rather interested in full scale transformer drying ovens for a more advanced treatment of your transformer? Then, our Hering transformer drying oven product line might be the right choice for you.

Still not found what you were looking for? Take a look at our products page for our most popular products or get in touch for customized solutions. We will build the right product for you!