The principle
ARRAS MAXEI auto-adaptative process keeps the active part in the water vaporization zone (gaseous phase), in order to optimise the cycle time and avoid all phase of needless cycle.
ARRAS MAXEI auto-adaptative process uses the core notions of thermodynamics and more precisely in function to the tension curve of water vapour.
This curve represents the transitions of water phase.
The points on this graphic that are more known are the best example to understand under the points 0°C / 1000 mbar and 100°C/1000 mbar.
ARRAS MAXEI drying process of the transformers is divided into three phases:
1° phase : Increase in temperature
The heating
The vacuum
This phase enables the temperature increase of the active part of the ambient temperature up to the regulation temperature, since the regulation instruction is fixed at a temperature of > 100°C to enable the inlet in the water’s gaseous phase. The threshold of temperature maintaining enables the temperature homogenization of the active part. This time is then function of the weight and components of the part (thermal bridge).
2° phase : Auto-adaptative drying
The heating
The vacuum
This phase is the sequence of vacuum cycle and then heating cycle till getting the parameters defining the end of drying. For a part still dried, the process will only make one sequence.
So, the global duration of the drying phase will be directly linked to the quantity of moisture.
During this phase, the vacuum cycles have a time and final vacuum that is function to the transformer temperature at a pre-defined vacuum value and to the moisture content.
The heating phase is related to the temperature homogeneity in the room and to the transfer of the water molecules to the part previously dried.
3° phase : End of cycle
The heating
The vacuum
When the curve of vacuum run-down reaches a pre-defined form in function to the calibration of the plant, the end of the cycle is engaged. That makes the temperature increase followed by a final vacuum cycle till the plant stopping by voluntary action. This phase enables to overcome the cycles’ ends the week-end or other bank holidays.
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