Cellulose particles' effect on the electrical field distribution between palm oil and mineral oil insulation systems

The power transformer is one of the most important parts of the electrical network. The majority of high voltage transformers are filled with a liquid that functions as an electrical insulator as well as a heat transfer medium. An alternative that has been proposed is palm oil based oil which has a high potential to be used nowadays for the insulation of high voltage transformers. This study presents experimental results between palm oil (PO) and mineral oil (MO) on the influence of cellulose particles of transformer oil under AC voltage and its effect on the electric field distribution under AC electric field. When a voltage is applied to the oil with the cellulose particles, the particles begin to move across the electric field. The higher the AC voltage used, the greater the amount of particles that accumulate on the surface of the positive and negative electrodes. When the AC voltage reaches 25 kV for MO, cellulose particles appear to be merged in both electrodes. But for PO, the cellulose particles look unconnected in both electrodes due to the viscosity of the oil. The cellulose particles are observed to fully bridge when subjected to the 35 kV applied voltage. The electric field of the contaminated MO show higher values than those of the PO sample. This may be due to its higher viscosity than MO and causes the movement of cellulose particles in PO to be slower.