TDOS Series:

The transformer is the heart of the power circulation system. To maintain the transformer to its peak performance high purity of insulating oil is a very prime important. Excessive moisture in transformer oil significantly reduces the dielectric strength of the transformer oil. To maintain the moisture-free insulation papers in the transformer, minimac designed transformer dry-out system can play a decisive role.

TDOS is an online dry-out kidney loop system and can be easily connected to a charged transformer for drying out the transformer. It works on the principle of moisture absorption. Oil passing through the series of inline moisture absorption cartridges where moisture gets absorbed and moisture-free oil returns back to the transformer. The TDOS equipment with the moisture sensors at the inlet and outlet provides automation to regulate the process, when inlet oil moisture reaches the desired level, the machine will automatically stop. Also, the machine is designed with interlocks to protect the transformer's safety.

The system is capable to remove the water contamination from the oil more than 5% to less than 0.01% in a short time.


  • Coal & metal mines
  • Power utility plants
  • Power substations
  • Power plants – coal, gas, hydro, nuclear, wind, solar
  • Steel plants
  • Metallurgical fields
  • Railway Sector
  • Automobile manufacturing
  • Chemical sector
  • Oil & gas industries CPP plants
  • Industries that require an on-site transformer

Types of oil which can be cleaned:

  • Transformer oil
  • Insulating oil


  • It removes the moisture and impurities from the oil
  • It removes the dissolved gases from the oil
  • It keeps the breakdown voltage of the transformer oil within the permissible limit
  • It increases the life of transformer oil as well as transformer
  • It can be used to perform evacuation of the transformer to dry out in overhauling
  • It can be operated while the transformer is in charged condition
  • It can protect the transformer from unplanned shutdown and heavy economical losses