Tag Archives: transformer oil

What is better “drought” or “rainy season” – the percentage of moisture in dry transformer oil

Tierra Fuller, , ,

Transformer oil aging results in degradation of its properties. The aging process is accelerated by influence of water, air or contaminants. Moisture and air cause the oil to oxidize, which lowers it’s dielectric strength, causes sludge deposits on transformer internal insulation and damages the insulation by the acidic products of oil decay.

Water may be present in transformer oil in various states: solved, emulsified or free. Even new oil contains solved water. Free water mostly accumulates in the lower parts of oil lines and in heat exchange devices. Water is solved in oil under the influence of high temperature. During operation water content in the oil increases, and may be extremely harmful for a transformer.

GlobeCore’s equipment allows removal of contaminants, including water, directly on energized transformers in compliance with the highest international standards.

Complete transformer oil filtration and regeneration systems are designed for full range of services to purify waste oil. The units are equipped with adsorbents for restoration of oil performance and improving its color.

According to international research, various sorbents may be used for drying of oil, as well as for retention of oil aging products. Some of the sorbent may be reactivated, which makes GlobeCore plants not only highly advanced by also very sensible in terms of return on investment.

The UVM type mobile oil plants are designed for the following operations:

  • Dehydration of oil for moisture content of no more than 10 ppm.
  • Degassing of oil to no more than 0.1% of gas content by volume.
  • Increase of dielectric strength to at least 70kV.
  • Drying of electric equipment with simultaneous oil purification.
  • Initial filling of dielectric oil into electric systems;
  • Nitrogenation of oil;
  • Vacuum evacuation of transformer and other electric systems.

GlobeCore’s plants significantly increase oil processing stability and consistency and improve oil performance.

Tests and Trials: Sport, Art or Industry? Analysis of Transformer Oil Purification

Tierra Fuller, , , , , , ,

The correct use of oil guarantees the reliability of industrial equipment and the prevention of equipment failures.  Transformer oil is a dielectric insulator and a coolant.  It also serves as an arc extinguisher preventing shorts and internal fires.

Transformer oil parameters degrade over time as the oil ages.  Oil oxidation is mostly caused by external elements such as water, air, acids and heat.  Aging of oil is best indicated by its acidity level, water content, and sediment and sludge formation.

Sludge accumulates in the solid insulation, the core, in cooling channels and other places inside the transformer.  Sludge is a dangerous enemy that degrades the oil’s cooling and heat transfer capabilities and damages the solid insulation causing it to disintegrate.  A short-circuit in the transformer windings becomes a much higher possibility due to oil degradation and sludge build up.

The acid level of the oil, as measured by the “Acid Number“ is the main indication of oil degradation and oil aging.  Acidity is measured by special litmus paper that changes color when subjected to contaminants.  Acids can damage cellulose insulation and metal parts of the transformer.  Acid levels can also measured through an oil analysis program.

The Acid number, as the main indication of transformer oil quality, is the amount of grams of KOH required to neutralize all free acids in one gram of oil.  The Acid number indicates how much the oil has aged and whether it should be regenerated using the GlobeCore Process.  Once the Acid number reaches 0.08 and higher, the transformer oil becomes aggressive and begins to destroy the solid insulation of the transformer.  The Acid number therefore, is the best indicator of when to service your transformer before irreversible damage is done to the insulating paper.

Besides chemical parameters, transformer oil must comply with certain physical and electric parameters.  Degradation of these important oil qualities may indicate problems inside your power equipment.

For instance, the oil’s flashpoint must be high enough to ensure fire safety in overload conditions and high temperature increases inside the transformer.

Dielectric strength of transformer oil is important for the prevention of breakthroughs in the transformer insulation.  This parameter is measured regularly by high voltage breakthrough indicators.  Transformer oil is tested six times with 10 minute intervals between each test.  The average of six tests is used to determine the dielectric strength.  If the results are unsatisfactory, another sample is tested and a decision on the course of action is made.

Fresh or used transformer oil must be tested before being placed into the transformer.  Some parameters tested are particulate matter content, general oxidation stability, transparency, dissipation factor, flash and setting points, viscosity, acidity and water content.

These measures are designed to identify and resolve problems before the they can cause a transformer failure shutting down the transformer.

Transformer oil is purified of contaminants, acids and gases in purification and regeneration equipment specifically designed for transformer maintenance.  Complete preventive maintenance systems, such as the GlobeCore CMM-R line of equipment will reduce costs and downtime while increasing operating profits.

Why do we use dry and clean transformer oil? Importance of transformer oil purification.

Tierra Fuller, , ,

Reliable operation of transformers is dependent on the condition of internal insulation. Transformers are insulated by liquid (oil) and solid (cellulose) insulation. Dielectric oil accounts for about 80% of the system’s dielectric strength. It is a very good dielectric, and it permeates cellulose insulation further increasing the dielectric strength of winding insulation material. Viscosity characterizes the oil’s cooling ability.

The oil must be protected from oxidation, avoiding overheating and contact with contaminants, since most of transformer failures are due to insulation failures.

Cellulose materials are the weak link of transformer insulation. Contamination of internal insulation by things like water, dissolved gas and solid particles cause degradation of insulation materials. Cellulose insulation quickly accumulates contaminants.

One of the main factors of transformer oil and solid insulation degradation is water. It inevitably enters insulation systems. The result of its influence (along with other contaminants) is aging of oil and formation of various degradation products, sludge, acids etc.

oil

When oil absorbs air and moisture, the aging process occurs even under light loads. Water in transformer oil consists of free water, water solved in oil degradation products and chemically bound water. It is impossible to extract all water from solid insulation.

Transformer oil can accept more water at elevated temperatures. When oil is again cooled, this water precipitates form the oil and enters solid insulation. Cellulose insulation absorbs water form the oil and retains it. Acids resulting from oil aging have a negative effect on cellulose and metals and form soapy metal, aldehyde, alcohol etc which form acidic sediment on solid insulation, internal surfaces of the transformer, breathing system, cooling system etc.

While water and heat are damaging to solid insulation, correct maintenance of cooling and insulation system can extend their lifetime to 60 years. Equipment formerly used for transformer oil drying only is quite obsolete. At present oil can be restored entirely. The parameters of regenerated (reclaimed) oil are extremely close to those of new oil. Service life of well maintained transformer oil is virtually unlimited.

The modern comprehensive transformer oil purification plants include degassing, drying and lightening, as well as filtration and regeneration. The resulting regenerated product is as good as new. Therefore, new oil purchase costs are reduced. The cost of purchased and regenerated oil is recovered.

The cost of regeneration of used transformer oil is always considered in relation to the high cost of purchasing new resource and possible downtime costs. It is quite obvious that owners of complete transformer oil regeneration plants are always in advantage.

 

Uganda Electricity Transmission Company Limited (UETCL Uganda) to cooperate with GlobeCore

Noticias, , , , , ,

Our company is well know in every continent of the globe, and now we are focusing our effort on Africa.

GlobeCore experts Stanislav Sukhar (Export manager) and Yevgeniy Svirid (Oil purification plants lead engineer) paid a visit to UETCL (Uganda Electricity Transmission Company Limited) which expressed interest in teaming up with our company. UETCL operates many remote substations with transformers which fail quite often. Unfortunately, transformer failures and resulting power outages are still a concern in Uganda. Accoring to Christopher Mutyaba, UETCL Head of Maintenance Department, reparing or replacing a transformer can take up to six months. Transformer down time is a loss of revenue and a cause for customer dissatisfaction. The Nigerian Power Holding Company, a counterpart to UETCL, which operates 18 GlobeCore 10000 l/h Mobile Oil Purification Plants, recommended to GlobeCore to UETCL Uganda to upgrade transformer oil purification plants.

Among the recent developments in GlobeCore’s oil purification plants is a system addressing the issue of excessive foaming in the vacuum chambers of the plants, which often occurs with oil and contaminated oils.

“GlobeCore currently manufactures oil purification and regeneration plants with flow rates ranging from 160 to 10000 l/h. Timely oil purification and regeneration extends lifecycle of an average transformer by 25 to 30 years. It is achieved by constant monitoring of the state of oil and paper insulation with Dissolved Gas Analysis Monitors and timely application of remedial actions – oil purification or regeneration.” – says Stanislav Sukhar, GlobeCore Export Manager.

Our engineers often travel to clients to provide startup assistance and staff training. We also organize different seminars to share our experience in oil purification. The latest seminar took place in April in Kampala, capital of Uganda, at UETCL offices. It centered on benefits of transformer oil regeneration with Fuller’s Earth, environmental and operational advantages of oil regeneration over replacement with new oil.