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Transformer maintenance

Transformer maintenance

Normal operation of electrical devices depends on regular maintenance. Transformer maintenance is a prerequisite for its reliable operation.

How often is it necessary to perform transformer maintenance? It is not easy to give a clear answer to this question, since it depends on the technical condition of the equipment and no two units are the same. The standards set a maximum interval of four years.

Stages of transformer maintenance

Transformer maintenance usually begins with an external examination. If any defects are found, they should be eliminated. After a visual inspection, a number of preliminary procedures are performed, including: checking the reliability of connections, cleaning insulator radiators and tank, removing dirt from oil conservator, refilling oil and taking oil samples.

It is very important to perform a transformer leak test. A leak can happen because of unsealed tank lid and can be eliminated by tightening the bolts. Otherwise, seals are replaced. The seal material is generally made out of oil resistant rubber.

The tank and radiators are cleaned from dust and oil. Insulators are cleaned with gasoline. When refilling, it is important to keep new oil temperature close to the oil in transformer, within 5 ºC. The oil temperature is controlled by a special thermometer, which is located on the tank lid.

Attention is also paid to silica gel in the air dryer. If silica gel turns pink, it is replaced to guarantee reliable operation of the air dryer. Used silica gel is regenerated by drying at 100-120 ºС for 15-20 hours, or at 400-500 ºС for 2 hours. The process is complete when the adsorbent turns bright blue color.

A thermosyphon filter is cleaned depending on the acid number of oil. The acid number is determined by oil sample tests. If the acid number exceeds 0.1 mg KOH / g, it is necessary to perform the following:

  • Drain the oil from oil conservator.
  • Remove filter cover.
  • Remove sorbent container.
  • Remove used silica gel and replace with new (dry).

Maintenance of air transformers

Maintenance of dry transformers is somewhat different. After removing the tank cover, determine that there are no mechanical damage to the windings and other important components. Also, check the reliability of connections and grounding. It is advisable to dry a transformer with hot air, and also to wipe the insulators.

After maintenance procedures winding insulation resistance must be checked.


Measuring transformers are used to measure currents flowing in the circuit. Also, such transformers monitor the presence of the phase of an electrical signal and operate in a specific voltage.

The maintenance of a measuring transformer begins with cleaning it from dirt and dust, inspecting the insulation; checking the oil level in the tank and testing for leaks in welded seams and seals. Oil leaks are removed by tightening fastening bolts. If there is no result, a new gasket of oil resistant rubber is installed.


Maintenance of air transformers


GlobeCore produces a wide range of equipment that significantly improves transformer maintenance

Equipment available:

  • transformer oil regeneration;
  • transformer oil refilling units;
  • transformers evacuation and solid insulation drying;
  • oil heaters;
  • hot air drying units.

Equipment needed for Transformer maintenance

Oil filled, dry or measuring transformers need proper maintenance to eliminate the influence of mechanical, thermal and electrodynamic forces in the equipment. Transformer maintenance allows to detect the development of various defects and to prevent emergency shut-downs.

Depending on the work performed, there are routine and capital maintenance of transformers. Routine maintenance and repairs do not pose much difficulty. It checks the individual components that can deteriorate rapidly. Capital maintenance of a transformer includes testing all parameters, as well as a thorough inspection and repair of all parts.

It is difficult to determine maintenance frequency, since no two transformers of the same power are in the same condition. It is due to the changes in operating loads. Therefore, the standards set the maximum time for maintenance: routine transformer maintenance should be carried out at least every four years, and capital maintenance every eight years after commissioning and more often if necessary.


What equipment to choose for transformer maintenance?

Some maintenance can be performed manually with simple tools. For example, you can take oil samples, clean insulators and the tank; tighten nuts to restore the tightness of seals between the tank and the lid. But it is impossible to refill transformer oil without special equipment. Before refilling, the oil must be prepared (degassed, cleaned from impurities) and stored until it is added to the transformer.

GlobeCore produces equipment that significantly simplifies the operation of businesses specializing in repair and maintenance of electrical equipment.

GlobeCore recommends the following models:

  • UVD – easy to operate mobile plant for adding degassed oil to a transformer;
  • INEY –a unit for evacuation of power transformers and drying of solid insulation;
  • PPM – transformer oil heating unit. It is used before refilling or changing the oil;
  • “Mojave heat” – a hot air drying unit for drying a transformer tank with dry hot air. It protects the insulation from moisture entering the active parts of a transformer during depressurization, repair or maintenance;
  • CMM – degasses and cleans power transformers and transformer oil, removing mechanical impurities through a combination of treatment methods (heat and vacuum, adsorbents, filtration) and always achieves the best results;
  • СММ-R -restores important operational parameters of electrical insulating oil. The equipment can be connected directly to an energized transformer;
  • TSS – transformer safety system that connects an oil-processing plant to a transformer. It also monitors the oil level in a tank, tests for leaks and air in the connecting hoses.

GlobeCore regularly expands the functionality of its equipment. The transformer maintenance products can be equipped with additional sensors, as well as a remote monitoring and control system via mobile devices.

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