Tag Archives: transformer oil purification

Transformer Oil Purification in the Marine Environment

A prosperous oil and gas industry is one of the factors that has contributed to the sustainable development of the world economy.  It includes objects where the geophysical research is performed and operational and extension wells are drilled.

In recent years, the extraction of oil and gas has had a potential to grow which requires the exploration and development of new deposits of mineral resources  since the old ones have been depleted.

It should be mentioned that drilling operations are considered to be a basis for oil and gas production since about 70% of the world investments in this field will potentially accrue to them.

The table 1 shows the major sectors and its percentage in the oilfield services market.

Table 1

The percentage of major sectors in the world market for oil services


Name of a sector


1 Offshore drilling


2 Capital projects


3 Enhanced Oil Recovery


4 On-land drilling


5 Oilfield casing and tubular goods


6 Geophysical works


7 Oil and gas equipment


8 Others


The table shows that one of the major sectors of the oil industry is marine offshore drilling.  This is due to the fact that onshore oil and gas deposits are becoming depleted and the development of the sea shelf will render it possible to provide the world economy with hydrocarbon crude for many years.

The first records of offshore drilling date back to 1869 when the first patent for an offshore drilling rig was granted to T. F. Rowland.  This invention was designed to perform shallow water drilling operations in approximately 50 feet of water.

The first offshore drilling of any consequence was carried out in the USA  as early as 1891.  Since then, offshore drilling rigs have evolved from fixed shallow water unit to the mobile units that can simultaneously serve several dozen wells and store thousands of tons of fuel on board.

In general, marine offshore platforms consist of machines for well drilling, oil and gas extraction, worker accommodations, and power supply systems.  Besides daily needs, electric power is required for drilling rig drive systems.

The voltage distribution and supply lines are regulated by transformers.  An uninterrupted supply of electricity to an offshore drilling platform greatly depends on the operational reliability of the electric power transformers.

Research performed by The International Association of Engineering Insurers (IAEI) has shown that the majority of electric power transformer breakdowns are caused by liquid and solid insulation failures.

Transformer oil is used to insulate conducting parts of the transformer and to transfer heat from the heated parts of the transformer.

During the operational service life of the transformer, the insulating oil has the potential to degrade badly by being exposed to moisture, temperature extremes, and mechanical impurities.  All of these factors can cause transformer failures and adversely affect the whole drilling platform.

In some cases, they may lead to the failure of the expensive equipment and/or unscheduled downtimes of the whole drilling platform and will involve considerable cost for the drilling rig operators.

The above mentioned consequences however, may be prevented if the operator performs regularly scheduled transformer oil purification and regeneration in the marine environment.

GlobeCore has developed and is still producing equipment for transformer oil reclamation in the marine environment that has the following characteristics:

(1) compact in size; (2) explosion-proof design; (3) protection from moisture; (4) vibration dampening; and (5) protection from salt-water corrosion issues.

11667442_804952062957881_5192054319660316997_nGlobeCore’s Clean Marine Offshore Oil Processing Systems provide vacuumizing of transformers as well as the purification of transformer oils by removing mechanical impurities, water, gasses, and unwanted contaminants.

The following is a list of benefits of the GlobeCore Clean Marine Oil Processing Equipment:

(1) oil is restored to new like condition (the breakdown voltage is increased and the acidity is reduced);

(2) reduced need to buy and transport oil;

(3) oil’s service life is extended and the transformer’s service life is extended; and

(4) no hazardous waste and and risk of damage to the environment.

GlobeCore Clean Marine Oil Processing equipment may be operated in the following modes:

  • transformer heat up (oil is heated and filtered);
  • oil degassing (oil is filtered, dried and degassed); and
  • transformer vacuumizing.

GlobeCore is the best solution to the problems of transformer oil processing in the marine environment.

Silica Clay for Transformer Oil Purification

Transformer oil is used in electric power transformers, high-voltage bushings and oil circuit breakers to transfer heat from the heated parts of the transformer.  Additionally, the oil is used as a liquid insulation to help insulate internal conducting parts of the transformer’s windings and core.  Transformer oil protects the solid insulation from moisture by filling all the space inside the transformer’s oil storage tank and serves as a diagnostic tool in determining the condition of the transformer.  In switching devices, oil is necessary to quench an unwanted and dangerous arc.

Since oil filled electric devices are usually operated under heavy load conditions, transformer oil is exposed to a wide range of unfavourable factors such as: (1) temperature extremes; (2) atmospheric oxygen; and (3) flooding.  All these factors, either separately or together, will lead to the degradation of the performance characteristics of the insulating fluid and the solid insulation.

Transformer oil can degrade quickly based on adverse conditions and consequently will become unable to perform its intended functions.  All this may result in serious consequences:  (1) accidents; (2) expensive equipment failures; and (3) unplanned outages.  Transformer oil samples therefore, should be taken regularly and analyzed to prevent such consequences.  The degradation of the rated values of transformer oil requires the oil to be dried, purified, and degassed to remove mechanical impurities, water, gasses and sludge.

One of the most effective methods of transformer oil purification is through the use of adsorbents.  They are substances that are able to absorb the products of aging and moisture from insulating fluids.  Such natural materials as silica clay, bleaching clays, amorphous coal and activated carbon, silica gels, aluminum oxides and zeolites serve as adsorbents.  Natural adsorbents are eco-friendly and they are less expensive to obtain than artificial ones.  They have a high specific porosity and a high ability to perform adsorption.  Due to these characteristics, natural adsorbents are widely used in the industry.

Silica clay is a natural material with high stability and high porosity.  Additionally, it does not swell when wet and is resistant to acids and alkalis.  Silica clay includes finely grained amorphous silica (76-88%) and a mixture of clay, sand and glauconite.  This rock may be of white, grey or even black color.  Microscopic studies have shown that silica clay is formed from opal grains and the remnants of silicon skeletons of organisms, consolidated by siliceous substances.

One of the hypotheses of silica clay origin states that this material resulted from the structural transformations of diatomites and other suchlike materials.  Usually, a natural sorbent derives its name from the location of its deposits.  The bleaching characteristic of silica clay depends on the silica/alumina ratio:  the higher the ratio, the higher the adsorption characteristics.

Silica clay is recommended to be stored only in special dry rooms when humidity is controlled.  Prior to shipment, the substance grits are exposed to a thermal activation at between 150ºС and 200ºС with a subsequent sieving of small grains with a size of 3 mm on a special sieve.  The latter has 16 holes on 1 cm2 of the surface.

Silica clay used for transformer oil purification should meet the following requirements:

  • the amount of calcium and magnesium in dry silica clay should be no more than 2.2% and the amount of silic acid should be no less than 32.5%;
  • the apparent density of dry grits should be no more than 0.65g/cm3;
  • adsorption activity should be no less than 45%;
  • the size of the main grit grains should be between 3 and 7 mm and the content of grit grains with a size of 3 mm should not exceed more than 5% of the total volume;
  • no foreign impurities; and
  • humidity should not exceed 10%.

GlobeCore is one of the leading manufacturers and suppliers of technological equipment for purification and restoration of dielectric transformer oil and other oils.  The operation of GlobeCore equipment is based on separate purification methods as well as by combination.  The highest value is placed on the adsorption technologies through the use of bleaching clays, silica gels, and zeolite.

GlobeCore mobile oil processing stations have obtained a wide use and acceptance in more than 80 countries around the world.  This is due in part to its  innovative technologies that allows for sorbent reactivation rather than disposal of large volumes of hazardous waste.  Fully automated equipment can perform operations 24 hours a days without interruption on energized transformers.

GlobeCore ensures high quality purification of transformer oils with  no  losses of raw material.

A regular processing of insulating fluids on the GlobeCore mobile purification plants extends the service life of the transformer,  reduces the financial expenditures for new oil, and eliminates the risks of accidents and equipment downtimes.

The CMM-C Vacuum Transformer Oil Purification Units

Unfortunately, in today’s industrial market place, the suppliers of insulating and lubricating oils are not able to provide the purity class necessary for trouble free servicing of oil products.  Therefore, bringing the oil’s performance up to required specifications remains an issue.

GlobeCore offers trailer mounted transformer oil purification/high vacuum degassing systems designated as the GlobeCore CMM-C line.  These technolgically advanced systems improve the oil’s performance characteristics that have become degraded due to heating and the introductioin of moisture and other unwanted contaminants.  These trailer mounted systems may also used to purify hydraulic fluid, transmission fluid, turbine oil, diesel fuels, industrial oil and other types of oils used in a wide range of industial and commercial applications.

GlobeCore’s thermal vacuum technologies remove water, gasses, and mechanical impurities from oils with a viscosity of no more than 70 cSt at 50ºС. Additionally, they may be used to vacuumize large and small transformers and vacuum fill different equipment under high or low pressure.

Transfromer Oil Purification Equipment by GlobeCore


CMM systems designed and manufactured by GlobeCore can perform the following functions: Degassing, dehydration and filtration of transformer oil, cable oil, turbine oil, and other industrial oils.  The CMM units remove gases, free and soluble water, and particulate matter from oils and fluids.  The CMM units are used in the installation, repair and operation of oil-filled high voltage equipment up to 1150 kV (power transformers, high-voltage switches etc.) as well as industrial turbines.

The GlobeCore CMM units perform the following services:

  • Purifying and drying of Transformer Oil
  • Vacuum filling of Transformers and Electrical apparatuses
  • Drying and Purifying of oil in transformers (on and off-line)
  • Vacuum Drying of Transformers
  • Degassing of Transformer Insulating Oil
  • Filtration of Transformer Insulating Oil

Technical Description

GlobeCore CMM units are designed as multipurpose Transformer Oil Conditioning units for field or factory use.  The units incorporate high capacity multi-stage electric oil heaters,  large capacity Vacuum Pumps with external connections for Vacuum filling work, three (3) stage particulate filtration systems, and connections for a large variety of service applications.

The Unit’s measuring devices include vacuum, pressure, and temperature meters.  The equipment can also be optionally supplied with a “water-in-oil” measuring device.  Installation of a water-in-oil measuring device allows in-line monitoring of water content.

Flow rates are variable from 0 to >10,000 liters per hour (L/H) and heating from 24KW to 210 KW in four stages.  GlobeCore systems are designed for easy operation and maintenance.

The principal functions of transformer insulating oils are to serve as a dielectric medium and as a transformer coolant or heat transfer medium.  In order to perform these functions, transformer oil must have the necessary qualities at the time of initial impregnation and filling at the factory and later be able to maintain the same quality in normal operation.

High Vacuum Treatment improves insulating fluids that includes transformer oils and silicone fluids. GlobeCore transformer oil purification equipment was developed as a result of 30 years of experience in vacuum treatment of transformer oils.


Every company dealing with oil-insulated high voltage equipment (transformers, high-voltage switches, turbines, etc.), shares the problem of having to change and dispose of contaminated oil and fluids.  The costs of changing and disposing of insulating oils are frequently very high and need a significant investment in time, labor, and money.  At GlobeCore, our equipment offers a practical, proven and economical method to purify oil so that it can be used again and again for your high voltage equipment.

Thermally accelerated Vacuum Dehydration and Degassing of Transformer Oil has gained wide acceptance as one of the most economical methods for the removal of dissolved water and gases.

On-Site Transformer Oil Purification is the most cost effective transformer maintenance service in existence today.  The GlobeCore CMM units not only purify the oil within the transformer, but actively regenerate the Transformer Insulating System by removing impurities that had become built up within the transformer over time.

Thermo-vacuum purification and degassing of transformer insulating oil, as performed by the GlobeCore Process, will result in the improvement of the condition of the entire insulating medium of your electric power transformers.

Here are some additional benefits of the GlobeCore Process:

  • Removal of dissolved moisture from transformer insulating oil
  • Reduction of combustible gases and oxygen
  • Improvement of insulating oil dielectric values
  • Improvement of transformer insulating oil power factor
  • Extension of oil service life
  • Extension of transformer service life and reliability

We at GlobeCore are committed to provide our customers with high quality products that satisfy technical and economic objectives.  We offer our vast experience in manufacturing, servicing and operation of transformer oil purification systems to your company.

Machines by GlobeCore come with a block of approved original equipment spare parts.  These spare parts meet all specifications required of the engineering process.  Over the years, optimal and high quality components have been carefully selected for our equipment.  GlobeCore guarantees the performance of our machines and the results of the oil treatment processes.  We have placed our equipment in more than 70 countries around the world and a reference list available upon request.

Short Process Description

Hot Filtration Mode

A gear type pump draws in the oil for processing via a valve and a strainer.  Processed oil is then pumped through the cartridge filter, the three-way valve and is then discharged to the processed oil vessel via a connecting line.

The above mode is also used for transformer core drying.  Transformer oil is circulated through the oil purification equipment.  After filtering the oil to remove the particles, the oil is heated up to max. temperature of 800C/1472F.  All residual gases are removed and the moisture is evaporated in the vacuum degassing chamber.  Residual moisture content can be reduced down to less than 3 parts per million (ppm).  Oil purification is a necessary maintenance process for oil-filled transformers and can be employed for removal of moisture from the transformer’s core and solid insulation. Heating of the transformer oil moves the moisture from paper to the oil and allows for its removal from the transformer.  The most common mistake made by operators of transformer oil purification equipment is to stop the drying process after reaching oil moisture content of less than 5 ppm.  After some time, when normal transformer operation conditions exist, the moisture content of the oil increases. It is essential to dry the transformer oil continuously throughout a long period.

Transformer Evacuation

Another required process is the immediate evacuation of the transformer after pumping the insulating oil out of the transformer tank.  The “Vacuum Effect” on the insulation surfaces greatly improves moisture content removal.  The process must be repeated several times before the desired effects will be achieved.

Hot Filtration and Thermo-Vacuum Drying

A gear type pump draws the oil in for processing via a strainer and cartridge filter.  It then directs the oil to the heat exchanger where the oil is heated by the heat conductor.  The oil is then fed to the vacuum drier’s sprayer after being heated to 60C/140F.  The Vacuum Pump maintains vacuum in the vacuum chamber.  a Vacuum can be regulated by valve(s) and monitored on the vacuum meter.  Filtered hot air comes into the chamber and removes gases and vapor from the oil’s surface effectively drying the oil.  The air is then discharged into the atmosphere via an oil separator by the vacuum pump.  A gear type pump then directs the oil into the processed oil vessel.  A programmable thermal regulator switch monitors the plant’s function continuously and maintains the pre-set temperature.

Daria Shaddad Discusses the Seminar’s Program with Jordanian Collegues

The participants at this forum were most interested in GlobeCore’s CMM-R mobile oil regeneration plant.

The CMM-R plant, as part of the GlobeCore Service Life Extension Program, extends the service life of electric power transformers by restoring dielectric strength and chemical composition of the transformer insulating oil.

The main advantage of CMM-R unit is its capability to regenerate insulating oil in the transformer online and while energized.

Other products presented at the forum were the UVM-4/7 line of industrial oil purification plants, as well as the BV vacuum section line of products designed for the removal of various contaminates and gas products from transformers.

During the forum, which lasted for one and a half hours, the participants asked many questions and participated in a discussion regarding the equipment presented.

The Jordanian participants were especially interested in the automatic “sorbent reactivation” technology featured in the CMM-R units, as well as the capability of the CMM-R plants to regenerate silicon oils.

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

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.

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.


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.