This section provides an overview for oil-filled transformers as well as their applications and principles. Also, please take a look at the list of 14 oil-filled transformer manufacturers and their company rankings. Here are the top-ranked oil-filled transformer companies as of June, 2023: 1.Neeltran, Inc., 2.The Gund Company, Inc., 3.Schneider Electric.
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A transformer is a device that has two windings and uses electromagnetic induction to convert AC power applied to one winding into AC power of the same frequency with a different voltage in the other winding.
A transformer has a primary winding and a secondary winding, and the voltage of the secondary winding is determined by the voltage of the primary winding and the ratio of the windings. There are various types of transformers, but oil-filled transformers are the most commonly used for power applications in factories.
Oil-filled transformers contain insulating oil in a steel tank and an iron core with windings inside.
Oil-filled transformers are most commonly used in power conversion in factories, as mentioned in the overview. This is because they are less expensive than molded transformers, and since the outer box is made of metal and can be cooled by the oil inside. There is no need to install external fans, etc., and they can be installed both indoors and outdoors.
In actual applications, oil-filled transformers are used for voltage conversion from extra high voltage (AC voltage exceeding 7000 V) to high voltage (AC voltage exceeding 700 V) and from high voltage to low voltage.
Oil-filled transformers consist of a laminated iron core made of laminated silicon steel plates with wound wires and insulating oil sealed inside a metal casing.
The insulating oil repeatedly expands and contracts due to the influence of ambient temperature and other factors, causing air to enter the oil and causing it to deteriorate. To prevent this deterioration, a conservator is installed above the transformer, which is filled with nitrogen to prevent air from entering the oil due to expansion and contraction. In addition, the windings inside the tank are covered with a bushing, which insulates them from the surrounding environment while drawing them out to the outside.
The windings can be divided into the power supply side (primary) and the load side (secondary), and the winding ratio is set according to the desired voltage on the load side. If the primary and secondary winding ratios and voltages are N1, N2, V1, and V2, respectively, the relationship N1/N2=V1/V2 is established, and the voltage is proportional to the winding ratio. Also, if the primary and secondary currents are I1 and I2, then N1/N2=I2/I1, and the current is inversely proportional to the turn ratio. These relationships indicate that the power on the primary and secondary sides is the same.
Mineral oil is widely used as the insulating oil in oil-filled transformers, and is classified as Class 1, No. 2 mineral oil. Recently, environmentally friendly transformers using sunflower oil or rapeseed oil are also available. Although they are more expensive, they have the advantage of preventing environmental pollution due to leakage accidents.
In addition, by monitoring the condition of the insulating oil, the use of the transformer can be diagnosed for its remaining service life. These are called oil gas analysis tests, in which a portion of the insulating oil inside the transformer is sampled and tested. By checking the concentration of organic gases inside the insulating oil, the usage condition of the transformer can be determined.
When a transformer overheats, ethylene, ethane, and other gases are generated. Partial discharge of a transformer, for example, generates acetylene and hydrogen. Hydrogen is also generated by aging. Acetylene is an organic gas that must not be detected even in trace amounts because its presence indicates that an abnormality has occurred inside the transformer.
Oil-filled transformers are widely used as step-down transformers, and heavy electrical appliance manufacturers sell commercial transformers according to capacity. Most standard oil-filled transformers are self-cooled transformers, and the temperature rises with the load on the transformer. If an Oil-filled transformer overheats, there is a risk of insulation failure due to forced deterioration of the insulating oil and the resulting spillover accident to higher levels. In the worst case, the oil may catch fire, resulting in a fire. Therefore, keeping the temperature of Oil-filled transformers below the allowable value is an important item for management.
The maximum allowable temperature for oil-filled transformers widely used in general is 105℃. However, since it is also affected by external temperatures and temperature differences, the temperature is controlled at around 95°C or lower.
Oil-filled transformers are treated very delicately under fire safety measures. First, mineral oil used in oil-filled transformers is generally classified as Class 3 petroleum. Since the volume of insulating oil in a large oil-filled transformer exceeds 2,000 liters, the oil alone is classified as a hazardous material under fire regulations. However, when the transformer is connected to an electrical circuit, it is no longer treated as a hazardous material.
For example, when dismantling an old transformer, the moment the wiring is dismantled and disconnected from the power lines, it is treated as a hazardous material.
Since there are many possible specific cases, it is necessary to check with the fire department, etc., before taking action.
*Including some distributors, etc.
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Neeltran, which stands for New Energy Transformer and Rectifiers, is headquartered in New Milford, Connecticut. The company is now a part of AMSC and is an ISO-9001-2015 certified designer and manufacturer of its own rectifier transformers and DC rectifiers to customers around the world across diverse industries including aerospace, mining, and petrochemicals. In addition to transformers and DC rectifiers, the company produces reactors and inductors, and turn-key solutions. The company also offers repair, retrofit, rewind, and remanufacturing of rectifiers and transformers.
Stangenes Industries, Inc. started in 1974 and is headquartered in Palo Alto, California. The company is a manufacturer of magnetic cores and transformers used in the medical and research industries and various military applications. Customers include the United States Department of Energy as well as research facilities such as CERN and DESY in Europe and KEK in Japan. Transformers are the company’s primary product including pulse, isolation, current, and general transformers. The company also produces electromagnets, pulse modulators, power supplies, and magnetic cores.
Schneider Electric S.E. is headquartered in Rueil-Malmaison, France, and has been operating since 1836. Schneider Electric provides a number of products and services including electrical car charging, energy management software, surge protection devices, load banks, servers and HMIs, valve and valve actuators, feeder automation, grid automation, and SCADA software products, data center cooling and software, home automation and security, light switches, motion control and robotics, signaling units, solar and energy storage, RFID systems, as well as other hardware, services, and software.
Ranking as of June 2023 in United States of AmericaDerivation Method
|2||The Gund Company, Inc.||20%|
|5||WEG Electric Corp.||10%|
|6||Stangenes Industries, Inc.||10%|
Ranking as of June 2023 GloballyDerivation Method
|2||The Gund Company, Inc.||18.8%|
|4||Stangenes Industries, Inc.||12.5%|
|7||Fuji Electric Corp. of America||6.3%|
|8||WEG Electric Corp.||6.3%|
Derivation MethodThe ranking is calculated based on the click share within the oil-filled transformer page as of June 2023. Click share is defined as the total number of clicks for all companies during the period divided by the number of clicks for each company.
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