Virtually all existing types of power transformers in worldwide power transmission systems use transformer insulating oils. The insulating oils serve to provide liquid dielectric insulation to the core and transfer away excess heat.
Electric power transformers must function reliably and efficiently for many years. Preferably without unforeseen disruptions. It is therefore, the quality of the transformer oil as the transformer’s liquid insulation that plays an important role in helping to maintain the efficient performance of the transformer.
Many studies of insulating oils have been made to determine the most suitable and effective oil for use in electric power transformers. Some of these studies have lasted for decades. In this paper, we will examine what is transformer insulating oil and what are its main characteristics that facilitate the continuous production process of transformer equipment for use in the transmission of electric power throughout the world.
Transformer oil is first and foremost, a dielectric fluid. A dielectric fluid is a fluid that does not conduct electricity. It is used, as mentioned earlier, mainly in oil-filled electric power transformers as an insulating material and as a coolant.
Transformer oil is obtained by fractional distillation and subsequent treatment of the crude oil base stocks. The main objective of transformer oils is aimed at isolating and cooling the coil and core of the transformer. The oil prevents contact between the cellulose insulation and the windings with outside air and oxygen. The air and the oxygen contain contaminants that promote rapid oxidation and the formation of harmful deposits that reduce the service life of the transformer.
The type of transformer insulating oil used in a particular application depends directly on the type and capacity of the electric power equipment. In practice there are at least three main types of transformer oils (1) mineral oils (naphthenic and paraffinic); (2) silicone oils; and (3) bio-based oils.
The use of mineral type transformer oil dominates most industrial plants around the world. This can be attributed to the very good dielectric and cooling properties of the mineral oils and because of the cost effectiveness of such oils.
Naphthenic mineral oils are less resistant to oxidation than paraffin mineral oils. However, the oxidation products are usually lighter, so it is less likely that sludge from naphthenic oils will be deposited in the lower part of the transformer.
When choosing insulating oil for your transformer, you should carefully consider the following performance characteristics of the oils that are available:
- Electrical – dielectric strength, resistivity, electric damping coefficient
- Chemicals – moisture content, acidity, the presence of water and moisture
- Physical – tension, density, viscosity, flash point and pour point
Total market revenue for transformer oils is expected to reach $ 2.46 billion by 2017. Among the main factors responsible for the growth of the insulating oil market is the growing demand for energy in developing regions, the growth of investment in power grids in developed regions, and the expansion of and increased use of renewable energy sources needing a connection to existing power grids.
Key issues in the industry currently include the negative effects of the aggressive nature of the sulfur present in transformer oil and the high flammability of mineral oils for transformers. There has been an increase in the number of fires and emergencies associated with the use of mineral oils in transformers. The industry therefore, has developed oils that resist degradation, leading to more frequent use of transformer oils that are biological rather than mineral. The latter type is non-combustible and non-toxic in nature. Manufacturers of transformers have begun using bio-based oil due to the fact that it has a higher dielectric strength, a higher flash point, and a lower pour point than most mineral oils.
Oil producers and blenders have been quite active in introducing new kinds of bio oils for the transformer industry. A large increase in the use of bio oils has taken place in the North American transformer market. This is mainly attributed to the greater availability of biological resources in the USA and Canada.
The market share of Bio Oils is expected to further increase as the demand for biological transformer insulating oil is expected to grow considerably in the next five years.
In years past, the only correct way to dispose of used industrial oils involved taking the oil to a recycling center. The used oil could be recycled and purified using special processing equipment. The recycled oil was virtually identical to the characteristics of oil when it was new. But, given the high cost of oil processing equipment in the past, it was more profitable to sell the used oil to companies that specialized in the processing of used oil. Thus, the electric company was in compliance with environmental laws and regulations and may have been able to offset the cost of the new oil from the sale of the used oil.
The value of the used oil product depended on various factors such as type, volume, quality and the distance it needed to be transported.
Modern industrial technology offers a range of different methods of recovery and purification of used industrial oil without the need to remove it and transport it to recycling plants. This approach to processing used industrial oil has become economically advantageous because it reduces the need to buy new oil and it eliminates the used oil disposal problem.
There are several methods for the cleaning and purification of used industrial oils:
- The Mechanical method is the extraction of water and solid contaminants from the oil through the use of filtration, separation, settling, and washing with water;
- The Thermophysical method involves evaporation and vacuum distillation;
- The Physico-chemical methods involve coagulation or adsorption;
The chemical method is only used in case of a failure of the first three methods and involves sulfuric acid or alkaline cleaning (this procedure requires more sophisticated equipment).
Basically, regeneration of industrial oils depends heavily on the use of the physico-chemical method of adsorption. This method uses special absorbent materials that have the ability to absorb micro particles of dirt and moisture and hold them in their outer pores. The adsorption method of regeneration is so superior that upon completion of a full cycle of regeneration, the oil will be restored to new like condition.
With modern equipment designed for the cleaning and regeneration of industrial oils, the power transmission company can:
- Save money by eliminating the need to buy new oil because the existing oil will be used over and over again;
- Maintenance Budget cut – cleaning used oil will reduce preventive and corrective maintenance costs;
- Preserve resources and save the environment.
In today’s environmentally conscious society, very few companies choose to reuse the used industrial oil. This is a mistake and fails to take advantage of modern cost saving and resource saving technology that actually is better for the environment that used oil disposal.
In respect of the idea of resource and environmental protection, it is worth recalling a modern myth in the oil industry.
“Ecologically designed equipment and techniques are expensive and do not provide immediate evidence of their productivity.”
Like many other myths and urban legends, it is necessary to dispel this myth and enlighten the industry. One-third of the crude oil produced in the world today is directed to the production of industrial oils. The reuse of waste oil in your company therefore, will have an affect on the demand for new oil. Regenerating used oil will have a positive impact on the environment, reduce operating costs, and will improve equipment performance and service life expectations.
Since the recovery and purification of industrial oils with modern equipment can be done continuously with a one man crew, it is now less expensive and more environmentally sound to regenerate rather than dispose of used oil.
Using equipment for the cleaning and regeneration of industrial oils will protect the transmission company’s initial investment in transformers and reduces the amount of new transmission equipment costs since the service life of the transformer will be greatly extended.
One of the companies that has developed and implemented the marketing of industrial equipment for the regeneration of insulating oils is the industry leading GlobeCore company. The GlobeCore Process also involves oil purification, drying and degassing of transformers, turbine oil regeneration, industrial oil regeneration and the ability to regenerate all kinds of mineral oils with restoration of color and performance. At GlobeCore, all products are quality controlled and tested before marketing and commissioning. Quality control standards at GlobeCore meet or exceed the requirements of ISO 9001: 2001.
GlobeCore has developed a line of equipment that destroys the previously mentioned myth that is it too expense to reuse the used oil as opposed to regenerating the oil by investing in oil processing equipment. The GlobeCore Process of oil regeneration saves, time, money and extends the service life of your transformers. Why buy new oil when it can be restored with the GlobeCore Process.