What are the typical data for a paper-synthetic ester insulating system?
A higher temperature will ensure that a shorter time is needed to reach a moisture equilibrium state. At lower temperatures, this can take much longer to achieve. A single measurement of water content in esters through Karl Fischer titration does not enable the assessment of the dynamics of water migration in the insulation system. A Karl Fischer titration test result without an indication of the oil temperature at sampling will be of no value at all! An alternative is a capacitive sensor, this will give a more accurate indication of the real state of the moisture content in the insulation system. The aging rate of both cellulose and insulation systems needs to be considered to get to the actual state of the cellulose paper moisture content.