transformer insulation crepe paper type Kraft

Ingredients

cellulose, copper, inhibited mineral oil, synthetic ester, natural ester (soy-based)

Preparation Steps

Original Recipe Text

The paper samples were prepared from Kraft paper tapes (100 cm long, 3 cm wide, basis weight 145 g/m2). Tapes were wrapped into rolls with an average weight of 4.58 g and dried at 90 +/- 5 °C under a vacuum of 0.16 mbar for 16 h. Each sample set utilized five glass bottles containing the paper rolls and a 13.9 g copper strip catalyst. Bottles were filled with 225 mL of the specific insulating liquid (mineral oil, synthetic ester, or natural ester), leaving an air headspace. Impregnation was performed in a vacuum chamber at 0.16 mbar and 50 °C for 24 h. Thermal ageing was subsequently conducted in a heating chamber at 150 °C for durations of 24, 72, 168, and 336 hours in closed systems. (pp. 3-4)

Evidence

"transformer insulation crepe paper type Kraft was used in the tests in the form of tapes cut to the appropriate length. The basis weight of paper was 145 g/m2."

Remarks

This research investigated the ageing dynamics of dry cellulose paper (moisture < 0.5%) within a transformer insulation context. Mechanical strength was monitored via the degree of polymerisation (DP). The initial DP was approximately 901, classified as 'good' per IEC 60450 standards. Results showed that for dry insulation systems, the specific type of liquid dielectric does not significantly alter the rate of cellulose depolymerisation (p. 15). The study also highlighted the role of water as both a product and catalyst in the degradation process, noting that natural esters can mitigate moisture through hydrolysis (p. 14).