This paper is written to raise awareness of an important problem in the area of transformers, reactive power and geomagnetically-induced currents. The problem is important because of the possibility of transformer failure leading to prolonged and widespread blackouts. An estimate by Lloyd's, an insurer, puts the risk of insurance losses at between 0.6and2.6 trillion in the event of a major geomagnetic storm. While the risk of this storm is low, the chances of our power system surviving it are simply not known. Those chances depend, to a large extent, on the definition and measurement of reactive power, a topic that has been the subject of a long and sometimes bitter debate. This paper contributes to a solution by explaining the definition problem and pointing a way to a solution. The solution relies on aspects of measurement theory that have been developed in the last half-century or so. Anyone concerned with GIC and reactive power, and in particular the impact on transformers, should not feel comfortable.

1 aKirkham, H.1 aWhite, D.R. uhttps://ieeexplore.ieee.org/document/8494870/