A cell for the electrowinning of aluminium by the electrolysis from an aluminium compound dissolved in a molten electrolyte (50), comprises: (I) a plurality of non-carbon anodes (10), each anode being suspended in operating in the molten electrolyte by an anode stem (11) that connects the anode (10) to a positive current source; and (II) a thermic insulating cover (60,60') which covers the electrolyte (50) and through which each anode stem (11) extends from the positive current source to an anode (10). The insulating cover (60,60') comprises a plurality of movable sections (60) that together cover a substantial part of the electrolyte (50). Each movable section (60) covers a corresponding portion of the electrolyte (50) that is located therebelow and that can be uncovered by moving the corresponding movable section (60). The anode stem (11) of each anode (10) extends through the insulating cover (60,60') between two movable sections (60) or between a movable section (60) and a fixed section (60') of the insulating cover (60,60') when the sections (60) are in a covering position over the electrolyte (50). Each movable section (60) is movable to uncover the corresponding electrolyte portion without interrupting operation of any anode (10), for example by tilting, in particular pivoting, or sliding and/or lifting the section (60).