Transec Online Drying System for Transformers
Power Systems
Transec Online Drying System for Transformers
Enhancing Transformer Reliability with Advanced Moisture Management Solutions. Our cutting-edge technology helps prevent insulation degradation, reduce faults, and extend transformer lifespan—ensuring a stable and efficient power grid.
TRANSEC - Moisture monitoring & drying
The issue: Moisture is threatening the transformer
Moisture is one of the primary causes of failures for power transformers and one of the main degradation factors for the insulation paper. It, therefore, increases the risks of operation failures and shortens the life expectancy of the asset.
Unfortunately, moisture can appear in a transformer from several sources, which are external or internal and it has a complex dynamic between the oil and paper within the transformer. The use of silica gel breathers, sealed tanks or nitrogen blankets can avoid all or at least the most of moisture from the atmosphere to affect the transformer. However, when the transformer is energised, the production of water inside the insulation is a natural and inevitable occurrence over time due to the depolymerisation of the cellulose paper.
Only continuous filtration is efficient in removing moisture from a transformer
As moisture is created continuously and as it is one of the primary concern for the transformer safety and life expectancy, it seems counter-intuitive to apply a temporary solution for this ongoing problem. Also it is essential to note that more than 98% of the water in a transformer is in the paper, while a meagre amount is dissolved in oil. The diffusion time of water from paper to oil is prolonged. This is why punctual filtrations are not solving the moisture issue.
The issue: Assessing the amount of water in the transformer
Effective moisture management is essential to the safety and longevity of transformers. Because moisture distributes unevenly between insulation paper and oil, assessing its levels accurately can be challenging. The following insights explore the dynamics of moisture within transformers and the obstacles encountered in obtaining precise measurements
Moisture Distribution and Solubility in Transformers
- More than 98% of the water present in the transformer is contained in the paper insulation while less than 2% is in the oil. Unfortunately, the insulation paper is not easily accessible for water assessment.
- Water solubility in oil varies depending on oil temperature and therefore PPM differs also. Hence it is not possible to check the PPM value to define the amount of water in paper.
- If PPM and oil temperature are known some curves to link the water PPM in oil and the water content in the paper. But these curves are only really valid at equilibrium which is in general never reached on a running transformer.
Challenges in Measuring Moisture Levels in Transformers
- As the water diffusion time is faster from the paper to the oil than the opposite it is possible to reach on the same transformer, several very different PPM values for the same oil temperature even at a few days difference.
- As a result of the previous points, taking an oil sample once or twice per year to assess the moisture level in the transformer seems irrelevant.
- Furthermore, oil samples can be contaminated at the sampling time or in the laboratory. As the moisture level is anyway very low in oil, any contamination (simple contact with the ambient air) will affect the sample PPM result. The chart shows PPM analysis results of 7 different laboratories on 3 different oils.
The Solution
TRANSEC: Online Drying Sieves
TRANSEC is an online drying sieves. The unit consists of an electrical pump, special water absorber cylinders and measuring sensors to monitor the amount of removed water. The System can either be mounted directly on a Power Transformer or can be installed next to it. Two pipes are connected to the upper and lower part of the Transformer body.
After the unit is installed and switched on, the pump continuously cycles the transformer oil through the cylinders. Within the cylinders, water absorbing material removes the moisture from the oil. After this process, the oil goes through a particle filter to ensure its cleanliness before it returns back to the Transformer. An inbuilt deaerator insures, that no air will enter the tank. Every TRANSEC unit includes sample / measuring points at the inlet and outlet (to check the moisture content in the oil). An additional prefilter and a monitoring system can be added to the unit as an option.
