This paper presents a brief study of the processes behind the movement of a hot zone along a bar of superconducting material when a dc current is applied across it. This phenomenon is known as the direct current zoning effect. The superconductor used was YBa₂Cu₃O_7-δ (YBCO). The balance of ionic fluxes due to the potential difference and concentration gradient are analysed; it is suggested that this dynamic balance can lead to the zone becoming immobile at high driving forces.