Conduction in insulating oil Voltesso 35 doped with antistatic additives

The performance of antistatic additives as charge suppressants in the insulating liquid Voltesso 35 has been investigated in a wide range of operating temperatures, 24-105°C. The ionic additive Stadis 450 is found unsuitable as a charge suppressant in transformer oils because of a large increase in the liquid conductivity with as little as 2-5 ppm of Stadis 450 added. The additives 1-2-3 benzotriazole (BTA) and polyoxyethylene lauryl ether (P-ether) seem to suppress the charging of Voltessa 35 without affecting the conductivity of the oil; however, the power factor of Voltesso 35 doped with >2 ppm of BTA is higher than the maximum acceptable level of 0.5%. The addition of P-ether (2-20 ppm) is found to affect both the conductivity and the power factor of the oil to a much smaller extent despite reducing its charging tendency significantly