Dielectric integrity associated with circulating insulating fluids

The behaviour of transformer oil and other fluids used for the cooling and insulation of power system equipment is significantly influenced by enforced motion. Not only can charges generated by streaming electrification1 accumulate to prejudice dielectric integrity, but the dielectric strength of the fluid is also altered per se2 by the actions of the flow in a complex, but predictable, manner. Both these aspects need to be understood to permit informed design and operation of power equipment and appropriate countermeasures.