Gearless Mill Drive Protection Improvements and Its Behaviour at Minera Escondida Ltda.

A cycloconverter-fed gearless mill drive is a drive system that has hardware and software protection functions to protect the equipment in case of abnormal operating conditions, malfunctions or failures. For demanding applications in the mining industry, protections systems need to be reviewed considering special or abnormal operating conditions as well as the need of high system availability. Some protection functions have tripped in the gearless mill drives operating at Minera Escondida and have been reviewed subsequently. This paper describes improvements in the protection system implemented in the gearless mill drives currently operating at the Laguna Seca concentrator of Minera Escondida Ltda. The background of the new protection functions, related analysis and solutions are explained and experimental results are presented showing their operation.