Online transformer oil filtration is the process of purifying transformer oil without switching off the transformer. This method is widely used at high-voltage substations and industrial sites where continuous power supply is critical. Fluidex produces mobile and stationary units for online filtration, which remove moisture, dissolved gases, and solid particles from mineral insulating oils. The process helps maintain dielectric strength and extends equipment life, making it suitable for maintenance of power transformers in steel plants, chemical factories, and utility infrastructure.