In September 2014, GlobeCore employees started up a new CMM-10A oil purification unit in Poland. The CMM-10A is used to vacuum transformers and purify dielectric insulating oil.
The CMM-10A unit is designed and intended for heating oil used in electric power transformers, degassing of transformer oil, and transformer vacuumizing.
The main users of this kind of equipment are facilities that are engaged in mounting, repairing and servicing oil-filled, high-voltage electrical equipment.
Almost every production process results in waste products that can be used as raw materials for some other form of new production. The diminishing supply of oil resources will result in the recycling of industrial wastes in order to get new raw materials.
Such a term as ‘used lubricating oil’ (ULO) can be found in scientific publications, but what does it mean?
ULO is oil which previously had been in some type of industrial service and, as a result, became contaminated by physical and/or chemical impurities. The main difficulty is that when the oil was in service, some contaminants (water, dirt, metal particles, and chemicals) made the lubricating oil unfit for use.
Nowadays, ULO is one of the most common technogenic wastes that can cause serious environmental problems. The statistics show that the spent oil makes up about 20% of the total amount pollution found in surface water.
The recycling of used lubricating oil is of great importance because other ways (dumping or incineration of wastes) may lead to even greater environmental problems that result in great financial expenditures.
It is worth noting that the recycling methods must be chosen in such a way that they do not constitute threats to the biosphere. If you have read publications, dedicated to recycling of used lubricating oil, you may come across various terms such as recycling, purification, or regeneration.
The term ‘purification’ means a continuous or periodic processing of lubricating oil using such units as sedimentation tanks, filters, centrifuges, or adsorbers. An important point is that the final product of the purification process does not always match the quality of fresh oil. The purification may be followed by decoloration of used oil, but sometimes the performance characteristics may be below the acceptable range. Creation of some circular contours may be necessary to purify used oil without its discharge from the oil filled equipment. This procedure may be applied to engine, turbine, industrial as well as all kinds of transformer oils.
The term ‘regeneration’ usually means the procedures, aimed at reclamation of used oil’s performance characteristics to those of the initial product.
Regeneration is a set of more complex physical and chemical processes such as coagulation, adsorption, or sulfuric acid refining.
The de-sludging, filtration, centrifugation and vacuum processing are the major methods of the used oil reclamation process. More complex physical and chemical methods are applied if the oil is very contaminated or very old. The on-site regeneration of used lubricating oil can be very cost effective.
GlоbeCоre has developed and is still producing a variety of mobile oil stations in the CMM , CFU and CMM equipment lines. GlobeCore’s modern and efficient oil procesing equipment allows the equipment owners to extend the service life of oils and thereby greatly reducing the costs of new replacement oil.
GlоbeCоre produces equipment of German quality, which is recognized in more than 70 countries of the world.
A proper choice of oil purification equipment allows equipment owners and operators to solve a wide range of tasks that greatly benefit their production processes.
Many countries have practiced a method of separate collection of used oil that allows the companies to get a high-quality product, as well as a minimum amount of waste products from the regeneration and recycling processes.
It is therefore, the problem of collection and regeneration of used lubricating oil is of vital importance nowadays. If performed properly, the cost for regenerated oil may be reduced by 40-70% as compared with the new oil.
The high-voltage power transformer is considered to be one of the most essential and expensive elements of electrical energy distribution systems. It is no wonder that the operational reliability of the whole power grid depends on the transformer’s operation.
Not one industrialized country in the world can avoid the technological obsolescence of electric power equipment. Here are some examples.
According to the researche of the US Electric Power Research Institute, 65% of all transformers in the USA have served more than 25 years as of 1997.
In Japan about 30% of the power equipment have been in use more than 30 years.
The same thing is in Russia, where 45% of the transformers have operated for more than 20 years and 35% – more than 25 years.
In Ukraine, 40% of the transformers have exceeded their expected operational service life.
Therefore, the reliability of the energy systems in future will be determined by the service life of their transformers.
If to maintain transformers properly and remedy the developing defects quickly, the service life of the high-voltage power transformer may be extended up to 30 or even 40 years.
The obsolescence and/or failure of the high voltage transformer oil is a very pressing problem that requires an optimal solution. In most cases, the electricity distribution equipment breaks down as the result of long term operation without the proper preventive maintenance.
The main reasons for equipment breakdown is as follows: 22% – the material aging, 19.4% – construction defects, 16.8% – improper operation, 10.3 % – irrelevant influence, 5.8 % – off-design modes in the electrical grids, 4.2% – repair defects , 3.5% – climatic and external impacts.
High Voltage Transformer oil
The deterioration of transformer oil properties makes up about 20% of all power system disturbances: 9.2% – gas, released into oil, 7.47% – oil aging, 2.18% – oil contamination and 0.62 % – oil oxidation.
These figures concern only the cases that arise from the oil aging.
Sometimes a negative impact of the aging products on the solid isolation is not taken into account.
Nowadays, the oil oxidation products (hydroperoxide and water soluble acids) are proved to reduce the cellulose polymerization degree, and that affects the durability of paper insulation. Additionally, the electrical strength and the service life of the insulation largely depend on the moisture content. If there is a high content of moisture in the insulation, the paper fibers are separated and then get into the oil, reducing its electrical strength. The dielectric strength is reduced by 20-50% if there are gas bubbles in the oil. As a result, there are partial discharges that reduce the dielectric strength of the whole liquid and solid insulation system.
Taking everything into consideration, there is no doubt that normal operation of high voltage transformer oil is determined by the liquid insolation – transformer oil.
GlobeCore has developed and is still producing equipment that provides for the preservation of performance characteristics of transformer oil.
GlоbeCоre equipment allows for the purification, drying and degasification of not only transformer oils, but also industrial, turbine, and hydrualic oils.
It is therefore, GlоbeCоre equipment thta enjoys widespread popularity in more than 70 countries of the world.
Particular attention should be paid to GlоbeCоrе equipment designed for transformer oil reclamation.
In the course of the oil reclamation process, the properties of the dielectric oil are restored to the original specified values and the aging process is tolled.
It allows the enterprises to extend the service life of oil as well as high voltage transformer oil. Thus, the enterprises can avoid considerable financial expenditures as they will not have to buy large quantities of new oil.
Dielectric strength is one of the most important indicators that describes the insulation characteristics of transformer oil. In number, this strength is equal to the relation of breakdown voltage and the distance between the electrodes.
The breakdown voltage is a characteristic that is very sensitive to the impurities and water in dielectric liquids. The dielectric strength may be drastically reduced by water supply or increased amount of foreign particles.
Pure transformer oil is usually free from water and mechanical impurities and its breakdown voltage is greater than 60 KV(kilowatt). But ,in general, the dielectric strength is a changeable characteristic of insulating oil.
Under the impact stress, mechanical impurities almost do not influence the electrical strength. It is known that the dielectric breakdown mechanism is not the same during the impact and constant stress. It is assumed that during the impact stress, the dielectric strength is higher than during the constant one. The risk of breakdown therefore, is small in the case of lightning discharges or switching surges.
If the temperature increases from 0 to 70ºC, the dielectric strength is increased as well. It may be caused by such factors as the moisture disposal or decreased oil viscosity.
Dissolved gases are no less important in case of breakdown. There are bubbles in the electrodes because of low tension of the electric field. The dielectric strength of non-degassed transformer oil falls if the pressure drops.
The breakdown voltage is improved by:
(1) degassing of dielectric liquid;
(2) impact stress; and
(3) high pressure (10 mPa (millipascal)).
The breakdown voltage depends on water concentration in the emulsion. Temperature falls or relative humidity of the air may cause the reduction of the dielectric strength or emergence of some water. Such phenomena may be also caused by the ingress of water into the oil blending process. This water is absorbed on the surface of a container.
The amount of water that enters the oil blending process may be reduced by substituting a glass container for a plastic one. In such a way the dielectric strength is increased.
It should be noted that there is no widely accepted theory of the dielectric liquid breakdown despite years of experience in this sphere. Still, there are three leading theories:
(1) The thermal theory states that a gas channel is formed by the boiling of dielectric liquids in points of high inhomogeneity of the electric field;
(2) The gas theory considers that a source of breakdown is the bubbles of gas dissolved in oil or adsorbed onto the electrodes; and
According to the (3) chemical theory, the breakdown is caused by chemical reactions passed in dielectrics under the influence of electric charge in gas bubbles.
But, there is one important point that unifies all three theories: the dielectric breakdown takes place at a steam channel realized by oil evaporation.
In order to avoid the breakdown of liquid dielectrics, it is recommended to use the equipment that is designed for drying, purifying, degassing and regeneration of oil products.
According to international standards, oil filled electric power transformer repairs are divided into three types: (1) minor repairs; (2) moderate repairs (Intermediate Maintenance); and (3) complete overhaul (Depot Maintenance). Minor repairs usually include only preventive maintenance, although some minor corrective maintenance may be included in this category. Minor repairs, including preventive maintenance, can be and usually are performed on site. In this category of maintenance, the transformer is not opened and the external power supply is not disconnected from the transformer. Minor repairs are usually performed by local service personnel.
The time needed to perform minor repairs and preventive maintenance will depend on the power of the transformer and may vary from several hours to as much as 1– 5 days.
Moderate repairs, or intermediate maintenance, includes all the operations of minor repairs and above, but usually requires the of opening of the transformer, lifting of the core, replacement of terminals (as required), coolant, switches, valves, oil pumps etc. Another major difference between moderate repairs and minor repairs is that it is always performed on a transformer that is disconnected from the power supply and performed at special repair sites known as depot maintenance facilities.
A complete overhaul includes the operations of moderate repairs with the addition of core repairs (with dis-assembly and restoration), replacement of the windings and the solid insulation. In some cases, the magnetic system is also repaired. The most common causes, that require a complete overhaul, is severe damage to the core, the windings and the paper insulation, usually as a result of surges and insulation failure. Insulating paper failure is usually due to a combination of age and degradation due to neglected preventive maintenance.
In order to avoid failures and the need to perform intermediate maintenance or a complete overhaul, it is important to routinely perform timely preventive maintenance. “Preventive Maintenance” serves to assess the service condition of the equipment and is designed prevent failures, service interruptions, and most importantly, it is designed to extend the service life of the transformer. Preventive maintenance is performed on transformers of 110 kV and above and 80 MVA. Preventive maintenance should be performed on transformers within 10 years of being placed into service and as necessary thereafter. The decision to perform preventive maintenance is made depending on the current condition, years of service, and test results from minor repairs including oil sampling and analysis.
Over time, the transformer’s insulating oil will degrade and lose its performance qualities and capabilities. Once an oil has reached an “Acid Number” of 0.08, the oil must be regenerated with the GlobeCore Process to prevent damage of the core and the insulating paper. GlobeCore offers its clients a unique solution: the UVR type regeneration units. The UVR Units are versatile and can regenerate and restore not only transformer oils, but other types of oil as well including hydraulic fluid, turbine oil, and other industrial oils and fluids. The UVR regeneration system lightens diesel and heavy fuel oil, gas condensate, petroleum and kerosene.
The UVR plants can be used by any related facility since they require no special placement, are easily transported and do not generate noise during operation.
Its time to get with the Process, The GlobeCore Process!
The company’s professionals attended a seminar in Amman, Jordan, on 15 April. The meeting was focused on equipment to improve efficiency of transformer operation.
GlobeCore’s Daria Shaddad and Yevheniy Svirid presented the main types of equipment which the company can offer for Jordan’s power plants.
In 2014, GlobeCore supplied and commissioned an automated mobile plant CMM-0.6A for purification and drying of transformer oil.
The unit uses classic vacuum drying process, as well as purification by multiple passes through a series of filters. The input oil’s viscosity must be below 70 cSt at 50 °С.
The unit is fully automated. It features a GSM module for remote control of the unit by cell phone. Error messages and process parameters are transmitted to the cell phone as text messages.
The CMM-0.6A unit will be most beneficial to facilities involved in installation, repairs and operation of transformers, oil-filled switches etc.
Visit our new office: 35 Main Road, Anderbolt Ext 31, Boksburg Gauteng, South Africa.
Tel: +27761054167
Att: Mr. Frank May
Oil Regeneration today has become a very interesting and important subject. Oils can be regenerated in a number of ways by different equipment and to varying degrees of purification.
GlobeCore has developed and built oil regeneration equipment for many different applications that involve regeneration and purification. The equipment varies widely in terms of number of applications and the degree of regeneration desired by the operator and include the following:
The following is a brief list of GlobeCore’s equipment for oil regeneration, putificaton and other industrial applications.
The full range of GlobeCore products is presented in the attached file, and can also be seen on the company’s website at www.globecore.com
The company has a global dealership network, and the products are supplied to more than 80 countries world wide. Certified explosion protection option is available. Production certified in accordance with ISO 9001 – 2000.