Operation of power transformers

One of the most important transformer operation requirements is temperature control. This is important due to the consequences which may be caused by overheating. For one, transformer oil service life is reduced.

Temperature is only one of the factors causing aging of dielectric fluid, and the oil must be maintained in good condition for as long as possible to save on purchasing new oil. To solve the problem, GlobeCore’s oil purification and oil reclamation plants work well. These products comprehensively purify insulation fluids, extracting solid particles, water, gas and aging products. Processing transformer oil every time acidity approaches a certain critical level allows to extend oil service life and save money. Beside, the amount of harmful emissions is reduced, since mineral oil is a hazardous and non-biodegradable.

To control the temperature of the transformer, the lid of the transformer is equipped with a mercury thermometer. Since the temperature of the device changes mostly due to the load, that should also be controlled.

Another important factor is ambient temperature. This obviously influences the temperature of the transformer. To prevent increase of temperature where the transformers are located, ventilation is required, natural or forced.

Transformer are fire-hazardous devices, due to flammability of the oil inside. Fire fighting equipment must be available and in good condition.

Scheduled transformer inspections are performed without taking the transformer off line. Schedule is usually recommended by the manufacturer.

Sometimes unscheduled inspections of power distribution equipment are required. One of the reasons may be a sharp drop of ambient temperature, since in this case transformer oil may leave the expansion tank. Another reason is disconnection of devices due to protection tripping.

When inspecting the transformer, oil level and color must be checked. There is a certain level, below which the oil must never fall. Good oil is light-yellow in color.

Preventive maintenance is performed on schedule. The decision of the need for preventive maintenance is made based on the information about the condition of the transformer and operating conditions. However, it is recommended in general that preventive maintenance is required at least once per year.

Some of the actions included in preventive maintenance of power transformers, taking the transformer off line, are:

  • external inspection;
  • repair of defects;
  • cleaning of insulators;
  • cleaning of the tank.

To ensure long service life of the oil-filled equipment, the load must be controlled. Of operation of the transformer doers not involve overloads, the life time of the transformer can be 20 years and more. However, keeping the load too low on purpose is also not recommended.

Correct parallel connection of transformers is performed if:

  • transformation ratios are equal;
  • connection groups coincide;
  • equal short circuit voltage;
  • phases of the connected circuits coincide.

Schedule of testing power equipment also depends on the operating conditions and general state of the transformers, as well as the results of previous inspections. Detailed information on these subject is given in local manuals, developed by the chief electrical engineer or another authorized person.

обновлено: June 24, 2016 автором: dannik