Effective insulation control monitoring system: The candi™ solution for a safer production

Abstract

The key to the chemical reaction necessary to convert alumina to metallic aluminium is the running of an electrical current through the cryolite/alumina mixture. The process requires the use of direct current, only around 4 volts but the amperage is very high, generally in the range of 180,000 to 350,000 amperes or more. In the meantime, various interventions are required on the electrolysis cells to complete the smelting process: handling of wasted and new anode, crust breaking, alumina feeding, interventions mainly performed by the Pot Tending Machine (PTM), electrically connected to the ground. Thus contact with electricity while performing on the potlines may result in hazardous situation such as short circuit of the Pot Tending Machine and/or serious and fatal injuries for the operator (electrocution due to high voltage up to 2,000 volts). Hence the importance of the electrical insulation of the driver’s cabin, the tools trolley and the tools themselves to avoid often irreparable situations. To prevent such risks and above all to make the work environment safer, ECL™ designed an efficient device able to monitor the insulation level to earth and giving an audible and visual indication of abnormally low insulation values: the CANDI™ system solution.