Lengthy Power Interruptions and Pot Line Shutdowns

Prolonged power outages are the major cause of inadvertent pot line shut downs in the primary aluminum industry (Kjar and Keniry in Reducing the impact of power supply interruption on potroom operations, 2007; Tabereaux in Light metals, pp. 1039–1044, 2010; Øye and Sørlie in Aluminium International Today, 2011; Dupuis and Tabereaux in Modeling cathode cooling after power shutdown, vol 1–2, 2012 [1‐4]). The rate of incidence of such events has been high over this past decade and in recent years it appears to be accelerating. The design of high amperage cells to be able to rapidly shed heat during operations is an emerging factor of risk when compared to older cell designs. Each event of an inadvertent shut down can cost tens of millions of dollars, most of this is from lost production. In this paper the authors explore the variety of root causes that have been behind extended power interruptions that have led to an inadvertent shut down of a pot line(s) and the recovery factors that may be involved with such an event. This will include an exploration of the typical time line that is involved from shut down through the restart of lost capacity.