Category Archives: Transformer maintenance

GlobeCore: Oil Purifier Protects Power Transformer and Extends Its Life by 20 Years

Globecore GmbH, a German company, manufactures oil purifier which  extends power transformer service life by 20 years.

Globecore protects and saves millions of dollars of investments in power transformers. This is achieved by transformer oil purification, which can be performed on site, with the transformer energized. Old oil is reused. Transformer oil is used in power and instrument transformers, as well as oil-filled switchgear. The oil insulates energized parts of the equipment, dissipates heat and extinguishes the arc in switches.

Transformer oil is used in power and instrument transformers, as well as oil-filled switchgear. The oil insulates energized parts of the equipment, dissipates heat and extinguishes arcs in switches.

What are the hazards of transformer oil contamination?

The transformer lives as long as its insulation system. Transformer gradually accumulates oxidation products, contaminants and other impurities over time when used. Oxygen and water in the insulating fluid provokes oxidation even under ideal operating conditions. Particles originating from the construction materials of the transformer are also a problem.

The process of oxidation results in formation of acids, which act on carbon and metals, forming aldehydes, alcohols and soap metals. These substances deposit on solid insulation. Contaminants increase oil viscosity, hampering circulation and cooling.

Therefore, aging of transformer oil is a consequence of combined effects of high temperature, oxygen, and electric field in the presence of the transformer construction materials. Important operational parameters of the insulating fluid (acidity, dissipation factor and dielectric strength) are very sensitive to its aging. The higher the intensity of the process, the sooner they reach critical levels, and the oil becomes impossible to use. Using such oil is also dangerous to the transformer: the risk of failures and power outages increases significantly.

What to do with used transformer oil?

Accumulation of waste transformer oil is a serious environmental concern. Consider this: over 40% of waterways in the world are contaminated and covered with a film of waste oil. One liter of waste oil makes a million liters of groundwater unusable! Plants and animals die due to massive pollution with oil products. Besides, waste oil contains carcinogenic substances. Dumping of waste oil into the environment is entirely unacceptable. So what is the solution and how to preserve the planet for future generations?

There is a solution: restoration of transformer oil to its initial condition and reusing the oil. Beside the pronounced environmental benefits, this solution allows to save on purchasing new and disposing of used oil, as well as to extend transformer lifetime by 20 years or more. At this time, the cost of one power transformer reaches, on average, hundreds of thousand US dollars. The number can easily reach into the millions, if the costs of disassembling the oil unit, transporting and installing a new transformer are factored in.

Transformer Oil Filtration Unit Globecore CMM-12R at electricity substation.

Transformer Oil Filtration Unit Globecore CMM-12R at electricity substation.

 

Methods of transformer oil purification

Let us consider several techniques used in filtration of used transformer oil.

Centrifuges. These devices are large drums in sealed cases. The drum consists of a number of conical plates with orifices. Centrifuges are used for removal of moisture and solid particles. At one time centrifuges were widely used in oil processing facilities despite their limitations, such as low capacity, complex design, intensive mixing of the processed oil with air and large footprint. With time, compact mobile units for oil treatment were developed, and the number of centrifuges operated is now on decline.

Electric purification. Electric purification is based on the uneven influence of the electromagnetic field on contaminants in transformer oil, which causes the impurities to settle on electrodes. The biggest limitation of this method is the complexity of cleaning the deposits from the electrodes. Also, electric purification cannot remove water. Due to these reasons, this approach has not been widely implemented  

Adsorption. This technique involves percolation of oil through a layer of adsorbent (silica gel in most cases), loaded into a vertical cylinder. Silica gel is produced by a series of chemical reactions, making the material rather expensive. Besides, there is a problem of silica gel disposal, since oil-contaminated materials must not be released into the environment.

The alternative is purification of transformer oil with Fuller’s earth, a natural adsorbent. Due to its porous structure, this material has good adsorptive qualities and can be used both for continuous regeneration of transformer oil from dehydrating breather filters, and also for restoration of oil drained from a transformer.

Generally, Fuller’s earth must somehow be disposed of, just like silica gel. However, GlobeCore process allows to reactivate and reuse the sorbent for transformer oil purification many times over.

Transformer Oil Degassing Cart. Oil Purifier.

Transformer Oil Degassing Cart

Thermovacuum dehydration and high vacuum degassing. The GlobeCore process using heat and high vacuum ensures the best parameters of transformer oil. Operation of these units is environmentally safe and does not involve special disposal or storage.    

GlobeCore environmental solutions

For many years, GlobeCore has been developing and implementing technologies for restoration of used transformer oil.

The company has successful experience in servicing power transformers of land based and offshore wind farms. We offer a range of units specifically tailored for these purposes.

The UVM type units degas oil and remove particulate matter by a combination of heat, vacuum and filtration. This unit reduces moisture content to 5 ppm and gas content to 0.1% or less and increases dielectric strength to 70 kV.

The CMM-R oil purification plants extend transformer lifetime by restoring the dielectric strength and chemical composition of transformer oil. This equipment allows to maintenance oil directly in an energized transformer. Connecting a CMM-R to an operating transformer allows to remove sludge from the windings and extract it from the oil by the sorbent. These units are loaded with Fuller’s earth.

Adsorbent Fuller’s Earth for Industrial Oil Purifier

Adsorbent Fuller’s Earth for Industrial Oil Purifier

 

The GlobeCore oil purification process has the capability of continuous processing of transformer oil, saving on new oil and disposal of saturated sorbents. Fuller’s earth can be reactivated up to 300 times, the equivalent of 1.5 – 2 years of operation or purification of 1000 tons of oil.

Zeolite drying cabinet GlobeCore ZSC-15

Zeolite drying cabinet GlobeCore ZSC-15

 

GlobeCore also cares about environmental safety of other machines which use adsorbents. The SSZ-15 zeolite drying cabinet can pre-dry zeolite to improve adsorption and the quality of oil dehydration. The CMM-4RP, one of GlobeCore latest developments, allows reactivation of saturated sorbents used in transformer oil filtration systems. The technology can reactivate the same sorbent at least 10 times. The reactivated sorbents contain no residual oil and, if necessary, can be disposed of a regular household waste without harm to the environment.

GlobeCore CMM-4-RP unit restores waste absorbent

GlobeCore CMM-4-RP unit restores waste absorbent

 

Therefore, GlobeCore transformer oil filtration technologies allow to:

  • save on purchasing new and disposing of used oil;
  • significantly lower industrial load on the environment;
  • extend transformer life by at least 20 years.

In conclusion, we would like to show some numbers to emphasize the economic feasibility of used transformer oil restoration:

  • average market price of restoring one liter of transformer oil is $0.7-0.8;
  • average price of one liter of new transformer oil is $1.5-2.
Globecore Oil Purifier CMM-12R

Globecore Oil Purifier CMM-12R

About GlobeCore:

Globecore Service center in Germany. dielectric Oil purifiers

GlobeCore is a manufacturing company researching, developing and producing various oil and fluid processing systems for use in several different industries worldwide and is the developer of the Power Transformer Service Life Extension Program and the GlobeCore Oil Filtration Process for servicing oil filled electric power transformers.

Globecore Service center in USA. dielectric Oil filtration

Contact Information:

GlobeCore GmbH

Edewechter Landstraße 173, Oldenburg-Eversten, Deutschland, 26131

www.GlobeCore.com

www.GlobeCore.de

Oil purifier

Globecore: Transformer oil maintenance

Globecore: Transformer oil maintenance

Electricity substation

Electricity substation

Electricity substation

About electrical substations

Electricity substation is a part of an electrical generation, transmission, and distribution system. Electricity substation transform voltage from high to low, or the reverse, or perform any of several other important operations. Between the generating power station and domestic consumer, electric power may flow through several substations at different voltage levels.
Electricity substation may be owned and operated by an electrical utility, or may be owned by a large industrial or commercial customer. Generally substations are unattended, relying on SCADA for remote supervision and control.
A substation may include transformers to change voltage levels between high transmission voltages and lower distribution voltages, or at the interconnection of two different transmission voltages. The word substation comes from the days before the distribution system became a grid. As central generation stations became larger, smaller generating plants were converted to distribution stations, receiving their energy supply from a larger plant instead of using their own generators. The first substations were connected to only one power station, where the generators were housed, and were subsidiaries of that power station.

Elements of a Electricity substation

Substations generally have switching, protection and control equipment, and transformers. In a large substation, circuit breakers are used to interrupt any short circuits or overload currents that may occur on the network. Smaller distribution stations may use recloser circuit breakers or fuses for protection of distribution circuits. Substations themselves do not usually have generators, although a power plant may have a substation nearby. Other devices such as capacitors and voltage regulators may also be located at a substation.
Substations may be on the surface in fenced enclosures, underground, or located in special-purpose buildings. High-rise buildings may have several indoor substations. Indoor substations are usually found in urban areas to reduce the noise from the transformers, for reasons of appearance, or to protect switchgear from extreme climate or pollution conditions.
Where a substation has a metallic fence, it must be properly grounded to protect people from high voltages that may occur during a fault in the network. Earth faults at a substation can cause a ground potential rise. Currents flowing in the Earth’s surface during a fault can cause metal objects to have a significantly different voltage than the ground under a person’s feet; this touch potential presents a hazard of electrocution.

Electrical substations Types

Substations may be described by their voltage class, their applications within the power system, the method used to insulate most connections, and by the style and materials of the structures used. These categories are not disjointed; to solve a particular problem, a transmission substation may include significant distribution functions, for example.

 

Distribution Electrical Substations

A distribution substation in Scarborough, Ontario disguised as a house, complete with a driveway, front walk and a mown lawn and shrubs in the front yard. A warning notice can be clearly seen on the “front door”. Disguises for substations are common in many cities.
A distribution substation transfers power from the transmission system to the distribution system of an area. It is uneconomical to directly connect electricity consumers to the main transmission network, unless they use large amounts of power, so the distribution station reduces voltage to a level suitable for local distribution.
The input for a distribution substation is typically at least two transmission or subtransmission lines. Input voltage may be, for example, 115 kV, or whatever is common in the area. The output is a number of feeders. Distribution voltages are typically medium voltage, between 2.4 kV and 33 kV depending on the size of the area served and the practices of the local utility. The feeders run along streets overhead (or underground, in some cases) and power the distribution transformers at or near the customer premises.
In addition to transforming voltage, distribution substations also isolate faults in either the transmission or distribution systems. Distribution substations are typically the points of voltage regulation, although on long distribution circuits (of several miles/kilometers), voltage regulation equipment may also be installed along the line.
The downtown areas of large cities feature complicated distribution substations, with high-voltage switching, and switching and backup systems on the low-voltage side. More typical distribution substations have a switch, one transformer, and minimal facilities on the low-voltage side.

Transmission Electrical substations

A transmission substation connects two or more transmission lines. The simplest case is where all transmission lines have the same voltage. In such cases, substation contains high-voltage switches that allow lines to be connected or isolated for fault clearance or maintenance. A transmission station may have transformers to convert between two transmission voltages, voltage control/power factor correction devices such as capacitors, reactors or static VAR compensators and equipment such as phase shifting transformers to control power flow between two adjacent power systems.
Transmission substations can range from simple to complex. A small “switching station” may be little more than a bus plus some circuit breakers. The largest transmission substations can cover a large area (several acres/hectares) with multiple voltage levels, many circuit breakers and a large amount of protection and control equipment (voltage and current transformers, relays and SCADA systems). Modern substations may be implemented using international standards such as IEC Standard 61850.

Converter Substations

Substations may be associated with HVDC converter plants, traction current, or interconnected non-synchronous networks. These stations contain power electronic devices to change the frequency of current, or else convert from alternating to direct current or the reverse. Formerly rotary converters changed frequency to interconnect two systems; such substations today are rare.

Collector Electricity substation

In distributed generation projects such as a wind farm, a collector substation may be required. It resembles a distribution substation although power flow is in the opposite direction, from many wind turbines up into the transmission grid. Usually for economy of construction the collector system operates around 35 kV, and the collector substation steps up voltage to a transmission voltage for the grid. The collector substation can also provide power factor correction if it is needed, metering and control of the wind farm. In some special cases a collector substation can also contain an HVDC converter station.
Collector substations also exist where multiple thermal or hydroelectric power plants of comparable output power are in proximity. Examples for such substations are Brauweiler in Germany and Hradec in the Czech Republic, where power is collected from nearby lignite-fired power plants. If no transformers are required for increase of voltage to transmission level, the substation is a switching station.

Classification by insulation

Switches, circuit breakers, transformers and other apparatus may be interconnected by air-insulated bare conductors strung on support structures. The air space required increases with system voltage and with the lightning surge voltage rating. For medium-voltage distribution substations, metal-enclosed switch gear may be used and no live conductors exposed at all. For higher voltages, gas-insulated switch gear reduces the space required around live bus. Instead of bare conductors, bus and apparatus are built into pressurized tubular containers filled with sulfur hexafluoride (SF6) gas. This gas has a higher insulating value than air, allowing the dimensions of the apparatus to be reduced. In addition to air or SF6 gas, apparatus will use other insulation materials such as transformer oil, paper, porcelain, and polymer insulators.

The “Sukhovey” Model by GlobeCore

The “Sukhovey” Model by GlobeCore is used to protect the solid insulation of electric power transformers from moisture.  Complicated, but also simple by design, the model remains one of the best the high-tech systems for the integrated treatment of contaminated oils and fluids anywhere in the industrialized world.

Here at GlobeCore, we believe that it is more cost effective to perform timely “Preventive Maintenance” rather than “Corrective Maintenance.”  It is usually easier and cheaper to prevent serious damage to your equipment rather than spending time and money to repair and/or replace that equipment after a major failure or breakdown.  Investments in equipment and maintenance however, need to be be justified.  So, let’s consider the possibilities and benefits of the GlobeCore “Sukhovey” model.

Over the last decade, a large number of the diversified technologies for serving oil-filled machines and equipment were developed.  Depending on the types and characteristics, there are models for pre-filtering oils, vacuum cleaning and degassing, sampling, laboratory studies, complete regeneration, lightning of fuels and many others.

The GlobeCore “Sukhovey” is designed to protect the internal solid insulation of electric power equipment.  Its mission is to clean the air that is used to remove mechanical impurities from the insulating oil tanks.

The Air-Drying unit present on the “Suhovey” is filled with an adsorbent material known as zeolite.  The unit maintains clean air by supplying it under pressure to the power unit for prevention of moisture accumulation.  It is also capable of preventing vacuum, formed by draining the oil, from interacting with potentially contaminated “outside” air.

The “Sukhovey” is composed of two adsorption blocks that are each 1 meter (1m)  in height.  The entire structure is designed so that the units works independently of each other and act as temporary replacements for the period of time it takes the zeolite materials to recover in each saturated block.

Air is supplied via a pipe to the collector where it is distributed from one of the adsorption units that contains the heated zeolite.  The air then flows through the ports to the heaters and is “ejected” under pressure through the hole at the bottom of the unit.

The “Sukhovey” is equipped with temperature sensors at both the inlet and outlet ports.  This not only allows the “Sukhovey” to provide safe and efficient control of the machine, but also to control the regeneration step of adsorbents due to the temperature differences.  The device operates with special zeolite adsorbents that are designed to absorb moisture.

The “Sukhovey” can operate continuously for up to 100 hours.  This is the maximum time during which you can choose not to enter the cyclic regeneration while using the “restore adsorbents” function.  If the model operates beyond this time it will require additional service.

See more video about transformer oil purification