Similar to the above, a major steel mill melt shop owner contracted our company to engineer, supply and install a new control system to replace an outdated DC contactor control arrangement. Due to rising maintenance costs, decreasing reliability, scarcity of replacement parts of the obsolete DC contactors and mill motors, and short supply of technicians that are qualified to troubleshoot the system, the customer elected to completely replace all the DC equipment. The redesigned system utilized variable frequency drive controls operating the new AC inverter-duty motors at a speed similar to the full-load speed of the old DC mill motors. All controls were housed in a steel container mounted on the bridge of the crane with a 100% redundant air-conditioning system. Additional items such as a new operator’s chair, festoon, disc brakes, positioning assistance, and collision avoidance systems were also installed during the conversion upgrade.